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Getting Around in GIMP - Skin Retouching (Wavelet Decompose)

2011-12-06T09:07:00.003-06:00

Image courtesy of (and copyright) Kelly Ealy (mouse over for original).

I have looked around quite a bit for a good method in GIMP to smooth skin for portrait work. I did find a few tutorials, but they all were mainly concerned with using Gaussian blur with a layer mask to "smooth" the skin. The results were almost always less than satisfactory.

The rest of my GIMP tutorials are all listed here: Getting Around in GIMP

Then I found the Wavelet Decompose plugin, and the search was mostly over for me.

Hoodie by Erik Olsson (mouse over for original)

I thought it might be helpful to walk through the theory as I approach it for skin retouching/smoothing, and how Wavelet Decompose fits into my workflow.

The main point that I have noticed is that what most people mean by "smooth" skin really means, "smooth" tones. See, real skin has pores, wrinkles, blemishes, etc. In fact, it's those pores and wrinkles that add "character" to skin. The lack of these features in skin will instantly cause an image to look unrealistic to most eyes.

Martina by Erik Olsson (mouse over for original)

I am very much of the opinion that any modification to skin tones be as transparent as possible - ie: they should not be obvious or immediately noticeable. I personally try to be as natural looking as I can (to my eye at least). Of course, this is a highly subjective thing, and one mans natural is another mans mannequin.

Another mans mannequin.

That is the problem with trying to use a gaussian blur on the base image to "smooth" the skin. You lose a ton of detail and end up with a smeared looking mess. All in an attempt to either smooth the tones of the skin, or to minimize the appearance of pores/wrinkles. Many times, both to some degree. If only there was some way to be able to modify the tones of the skin separately from the pores and wrinkles (and separate again from blemishes or freckles).

Oh, that's right, I mentioned Wavelet Decompose earlier!

If you want to practice some of the things I will be talking about, Flickr user Erik Olsson has licensed both Hoodie and Martina as CC-BY-SA-NC. I'd recommend going to grab one of those images (because really, who doesn't like looking at pretty Swedish girls?). The first image was graciously provided by Kelly Ealy for demonstration here, and was offered on this Model Mayhem practice thread.

Wavelet Decompose

What the WD filter plugin will do is to separate your layer into multiples layers with different sized details on each one and a final residual layer with all the rest of the information. Each of these layers is set to recombine using the Grain merge layer mode, meaning that each layer is added to the previous one to build back up to the final image. This means that we can suppress data at a certain scale level to keep it from contributing to our final reconstructed image.

This is basically frequency separation on your image.

If you're not sure what that means, it might help to see it in action. We'll use a 100% crop from Martina above:

The base layer 100% crop.

Now, running Wavelet Decompose on the layer and leaving the default options the way they are, we get 6 new layers: Wavelet Scale 1-5 and a Wavelet Residual layer. Let's take a look at each layer to see what we get:

Wavelet Residual

This residual layer is what is left over after all of the detail scale layers have been removed. Notice that it represents the global contrast and colors in the image.

Wavelet scale 5

Wavelet scale 5 is the largest details layer in this example. From here on each of the subsequent scale levels down to 1 will only contain finer and finer details from the image on their own. Look carefully at her skin on her cheek here. You'll notice that individual pores don't really show up on this scale, but the overall skin tones show up more. If the skin is "blotchy" or uneven in tone, it will show up very noticeably on this scale. I have found often that this scale level will often impact the overall perception of smooth skin tones more than any other, and it is usually here that I will start my editing.

Wavelet scale 4

Wavelet scale 4 shows some more overall skin tones and texture with just a hint of the pores coming through. Between this scale level and scale 5 is where I do most of my work. Rarely do I need to modify any of the lower scales unless I am targeting specific blemishes.

Wavelet scale 3

Pores are beginning to really become obvious now at this scale. This would be the largest pores in her face, and this scale is the contributor for the largest size.

Wavelet scale 2

The mid-size of the pores are very clear at this scale. Finer features like wrinkles will also show up clearly on this layer.

Wavelet scale 1

It may be hard to see, but the finest details reside here. These are the smallest scale contributors to the pores and fine lines. Stray hairs will sometimes individually show up here as well. (You can make out her eyelashes very nicely in this scale level for instance).

What you want to remember is that each of the scale layers is set to Grain merge layer mode, meaning each layer will intensify with the layer below it, all building up down to the wavelet residual (which is in Normal blending mode). I mention this because if you wanted to remove features from one of the scale levels you can easily just set your foreground color to medium gray RGB(128,128,128), and anywhere you paint on a scale level will remove those details.

If you try this on your own, a good way to understand what is happening is to turn off all the layers in your image, then turn on each of the scale layers starting from the smallest (Wavelet scale 1), one at a time. This way you will be able to see what the contribution of each layer is to the final result.

Retouching skin (in practice)

So, how can we use this information to help us retouch our images? Well, there are a couple of things to keep in mind before getting started...

The number of scales you use will be dependent on your image dimension size, and the relative size of features in it. I don't have any rules to help you decide this, but increasing the number of scales will give you a larger number of smaller frequency separations to work with. If you're just starting out I recommend staying with the default of 5 scales until you are comfortable with this technique.

I personally try to use as light a hand as possible, to avoid destroying too much detail in the skin. A good rule of thumb is, if it looks right to you, then it's too much - make it more subtle.

So, using the Martina image from above, I will open the image in GIMP, and run:

Filters → Generic → Wavelet decompose...

Leaving all of the defaults will leave me with 5 wavelet scales and a residual.

Remember you can use Shift-click on a layers visibility to isolate just that layer to view.

I will often do this with the residual and scale 5 layer to get a feel for what types of objects lie in those frequencies visually.

Now I will leave all the layers visible, and will begin using the Free Select Tool to begin selecting a portion of the face that I want to adjust. I will usually try to keep similar-sized features together, and will also try to follow the contours of the face and light. Once selected, I will also feather the selection by a good sized radius (around 30px radius in this example).

Once I have a region selected, I will then activate the highest Wavelet scale I have (5 in this case), and will try applying a gaussian blur to that layer. Choice of a blur radius is arbitrary, but I'll usually try to blur enough to smooth out the tones on this layer, but not to completely obliterate them. I finally chose 33px in this example. Keep in mind that subsequent scales will also be blurred, and the effect is additive to the final image.

Gaussian Blur, 33px radius on Wavelet scale 5 (mouse over to compare original).

Now with the same selection still, I will activate the next Wavelet scale layer down (4 for me), and will apply another Gaussian blur here as well. I generally tend to aim for approximately 1/2 - 1/4 of the previous blur radius. I finally decided on a 13px radius here.

Gaussian Blur, 13px radius on Wavelet scale 4 (mouse over to compare original so far).

The thing to notice when working on these largest scales first is that the underlying tones of the skin will begin evening out. If there is blotchiness, liver spots, sun damage, etc. those features can be softened or removed without affecting smaller features like pores as much. If this were me, I would stop here and begin pixel-level dodging and burning to clean up other things to my liking.

But, since we are learning, let's keep going and try blurring features on Wavelet scale 3 to see the effect.

Gaussian Blur, 6px radius on Wavelet scale 3.

If we used an even bigger radius on Wavelet scale 3, the effects get a little jarring:

Gaussian Blur, 16px radius on Wavelet scale 3.

This is what I mean when I say a light touch is really best. The 16px blur on Wavelet scale 3 blew us right past nice, neutral retouching into mannequin territory (and I don't want to have to link another mannequin image).

What's nice about using Wavelet Decompose is that on each of the scale layers, a neutral gray (128, 128, 128) color will suppress that feature at that scale level (effectively removing it). This means that you can grab a brush with gray, and selectively paint over blemishes or features that you want to suppress. Instead of using a blur, I could have used a brush with gray, and painted on her skin at each level with varying opacity to suppress those features.

This gives you pixel-level control of features directly with a simple brush, and the fact that the layers recombine with Grain merge layer modes means that you can see the results of what you are doing immediately on the image.

Once I am happy with a region of skin, I will then select a new region to begin working on, and will follow the same steps outlined above to get a result that I like. I like to break up a face into different areas based on the light and skin features. For instance, I will usually work on cheeks and just below the eyes separately from the nose, chin, and forehead. It's really a personal preference rather than a rule, though.

Remember to zoom out and get a look/feel for the result from afar - sometimes you can get too zoomed into a region and not realize what is going on.

I've included the .xcf file with my selection still active from the examples above. It already has the gaussian blurs on scale 4 and 5 done (but not 3).

Download the GIMP .xcf.bz2 file of the example (2MB).
(Just save it and open it directly with GIMP)

Hopefully this has been helpful to some of you out there. With a little perseverance we can eliminate the use of globular gaussian blurs over entire images as a technique for mangling skin. This is a very powerful method of image manipulation and does have other uses as well - did anyone notice that Wavelet scale 1 is a really nice high-pass layer for your image? Bet you could use it for some nice sharpening if you wanted! ;)

Experimentation is key here! Don't be afraid to try things out!

Questions or feedback? Let's here about it in the comments.

Getting Around in GIMP - Contour Painting

2011-11-02T16:13:00.000-05:00

Similar to using dodging and burning is something I like to call "Contour Painting". It's basically dodging and burning (d&b), but with an eye towards contours of the subject in a photo. I will use this very often in shots with skin, and a great example of this would be a nice cheesecake pin-up style image!

Lovely pin-up pose! (mouseover to see the final result)

First off, I want to thank Evolutions Photography for graciously allowing me to use this wonderful image as part of my tutorial. The model is the lovely Ariel Fulmer (Arielita on ModelMayhem). Make up artist is DmarieBelleza, and the hair stylist is Anna Marie De Almeida. I originally came across this image in the ModelMayhem Digital Art & Retouching Challenge forum in this thread.

The rest of my GIMP tutorials are all listed here: Getting Around in GIMP
If you want to retouch the skin before contour painting, see this tutorial:
Skin Retouching (Wavelet Decompose)

Planning

For the most part, the lighting in your image should already indicate how the major contours of your subjects are lit. This should be the baseline by which you begin enhancing those highlights/darks to begin adding shape. Remember - you will usually want to approach this with a light hand at first.

You should also have an idea of how strong you want the effect to be. If it's highly exaggerated it tends to look more like a mannequin or illustration in some cases, if it's subtle it can nicely highlight those portions of your images. If I am using it on a more natural image I will use it lightly on faces and to slightly enhance the shapes of interest (bare skin or interesting textures/folds in clothing).

With an image like this pinup, I want to push things to be more exaggerated for a very stylized look (see this search on Vargas for examples of what I am aiming for).

Looking at Contours

The trick to this method is an understanding of where the light is primarily coming from in your image, and what the shape of the objects are. This is best illustrated in images with a single light source (but can be used on just about any image), as you can easily tell where the highlights are on an object.

What you want to notice is: what is the shape of your object, and how do you want to enhance it in your final image?

Bonus! At the end of the tutorial is a link to the GIMP file I used while making this tutorial.

Dodging & Burning

The basic premise behind dodging and burning (d&b) is to manipulate the exposure in certain areas of a photo. In the old days we would actually do this on an enlarger by using something to limit the amount of light hitting our print (dodging), or by masking other areas of a print to allow extra light to pass through on certain portions (burning).

In the digital realm, GIMP has a specific Dodge / Burn tool for this. It is nice to quickly touch up an area, but works destructively on your image (it alters the pixels of the underlying image without a means for easy adjustment). We can achieve the same effect (mostly) by using extra layers set in Overlay (or Soft Light) blend mode.

With a new layer over our original image in Overlay mode, we can then paint with white and black values to selectively darken or lighten the areas we want. It's far easier to show this process rather than explain it, so on we go!

Set Up

The nice thing about this approach of using Overlay layers is that you can leave your base image underneath all the layers for different manipulations (like color changes), without affecting your d&b work.

Add a New Layer (Shift + Ctrl + N or Layer → New Layer...) to your image above any existing layers.

Make the "Layer Fill Type" Transparency.

I will usually name the layer something descriptive ("Legs" in this case) so I know which layer does what. This is helpful because you may use differing amounts of blur later for different regions.

Change the layer blend Mode to Overlay.

Now we are set up to begin painting over our image.

Contour Painting

This is where you want to pay attention to what the light is doing to the subject of your photograph. We'll start with highlighting portions of the image we want to pop a little bit (this is basically a "dodging" action).

The models legs are really the stand-out portion of this image, so we will start there. Here are the legs before anything is done to them:

Our original image.

From this view I can determine that I would like to highlight the shape of her legs, and perhaps enhance the volume a bit.

To do so, I will highlight the legs to exaggerate the lighting as it comes from directly in front of the model (notice how the center of the legs are well lit, with a fall-off of light as you approach the edges).

If you look closely, you'll see that the contour/shape of her leg is well defined by the light hitting the front. That is the guide to where we are going to paint on the highlights (dodging).

Choose your favorite painting tool, and set your foreground color to White. Remember - painting on this Overlay layer means that white will lighten, black will darken, and middle gray will do nothing to the underlying layers.

Painting on the contours.

I like to use the Paintbrush tool with a Fuzzy Circle scaled larger to allow me to lay a big stroke of paint at first.

Now paint white onto your "Legs" layer following the contours of her leg.

I don't have to be pixel-perfect just yet, because I am going to be blurring this white overlay in a moment to soften up those edges. I just aim to get the highlights along the most important areas.

This should get your roughly to where you are wanting to go.

After applying Gaussian Blur (88px radius).
Mouseover to see the Dodge Layer.

Now I apply a Gaussian Blur to the "Legs" layer to feather out the effect even further. This smooths out the transition, and makes it all look just a bit more natural.

The blur radius depends on the image size and painting size, but in general I try to make it large-ish. In this case it was 88px.

Now those legs are looking sort of shiny!

We could stop here, but to exaggerate the effect even further, we can use burning to cause the edges of the legs to drop even darker than they already are.

Painted and blurred "burning" along the edges.

To begin burning the edges of those legs, I'll add another new transparent layer to the image in Overlay mode. This time I'll name it "Legs Dark".

I'll keep using the same brush, but now I will change my foreground color to black (or any other value darker than gray, to taste).

I will now paint (burn) with a fuzzy brush just along the outside edges of the leg, following its contour again. I don't usually brush right along the edge, but rather just outside so I just kiss the edges with a little fuzzy black.

I sometimes apply another Gaussian Blur to the dark layer (this is highly subjective and up to you). In this case I did apply the blur - 88px again.

After erasing the burn layer from other objects
(like her left foot).

In places where the foreground leg overlaps the background leg, I will then go back and use the Eraser Tool to remove any unwanted burning from the background or other objects (the background in this image is white, so it makes it a bit easier).

Notice the models left foot is now not as dark from spill-over after I erased the burning layer from it.

Also notice that I have only done the right leg at this point. When multiple areas I am burning overlap, I will approach each one on it's own layer to isolate the work I have to do. So to do her left leg, I would create another transparent overlay layer just to work on her left leg.

Burning the left leg, after cleaning up with eraser.

After repeating the same procedure with a new burning layer, the left leg looks pretty good.

This was done on another Legs layer ("Legs Dark 2" in this case), which allowed me to separately control the amount of spillover with erasing, and will also allow me to independently control the opacity of each leg (to give me even more control over the final result).

That is basically all of the steps in what I call "Contour Painting". To finish this image off, I would basically repeat all of these steps for each area of interest where I want to paint and enhance the shapes and contour of our model.

The body with no contour painting yet.

To keep the overall shape highlights consisten, I will continue thinking in terms of highlighting the peak areas of skin (basically to keep a consistent look with the legs).

I will apply highlighting to her arms and portions of her face next, as well as the exposed portions of her stomach.

Contour painted highlights on her body.

A couple of new layers and some more contour painting produces this.

Again, a rather high-ish radius was used for the Gaussian Blurs in these cases (~66px this time around - and even smaller when doing finer details like her fingers).

The nice thing about using many layers for these operations is that I can now control the opacity and strength of the effect in different regions independently.

Finally some burning along the contours of her body, along with some added highlights in the hair.

After fiddling a bit more and then adjusting each layer's opacity until I got something I liked, we end up with this (mouse over the image to compare it to the original):

Mouse over the image to see the original.

There is still more yet to do to call this a finished image, as we haven't even touched color effects or pushing the background to pure white, but those are tutorials for another day.

Remember, I used this type of image because we can approach it with a heavy hand and still get results that look good. Also, try thinking about this technique in different terms that aren't so large. You can use the exact same procedures on features that are much smaller to adjust the local contrasts in whatever scale you'd like. (For instance, if I could have spent time dodging and burning every little fold of cloth in her top, or been more specific with her hair).

If you've followed me all the way down here, I have a treat for you: My full .xcf.bz2 GIMP file that I used to create this tutorial so you can fiddle with it yourselves!

Download the GIMP .xcf.bz2 file. (14.5MB)
(Just save it and open it directly with GIMP)

I know this tutorial has been long, but hopefully some people will find it useful in some way. After practicing a bit you might find it a regular part of your workflow! If you think it's been helpful, consider scrolling back up and hitting the "Donate" button (or maybe visit an ad). It helps feed my caffeine addiction!

This basic method can be used on just about any image that you take to give you even more control over the final results. Similar results could be obtained using local contrast enhancements, for instance, but this method really lets you decide where those enhancements could best be targeted.

I have found this also works to great effect on children's skin (which should appear smooth and soft anyway), and I will usually do some sort of contour painting on most of my images (even if it's just a tiny amount). Here are just a couple of other examples where I used this same technique:

Leila Being Devoured by Beverly, a photo by avhell on Flickr. (Mouseover to see original).

Whitney, a photo by avhell on Flickr.

Lauren, a photo by avhell on Flickr. (Mouseover to see original).

Mobile Gothic, a photo by avhell on Flickr.

DIY Ringflash Tests

2011-10-12T14:44:00.000-05:00

I recently had a party at my house for some co-workers of my wife, and managed to get a few of them to let me shoot some quick photos using my DIY ringflash. These are the results.

Whitney, a photo by avhell on Flickr.

Considering that I constructed the ringflash from 2 bowls bought at a dollar store, and an old plastic cup, I'm pleasantly surprised at the results. I still need to place diffusion material over the front to help soften the light a bit, but the overall effect is pleasing. I'll have a DIY tutorial on how I built the ringflash, as well as my softbox shortly.

To Randi, a photo by avhell on Flickr.

The rest of my DIY ringflash tests are here in my Flickr set.

Getting Around in GIMP - Luminosity Masks

2011-10-07T11:29:00.000-05:00

The rest of my GIMP tutorials are all listed here: Getting Around in GIMP

There was a recent thread on the GIMP users forum at Flickr on how to generate luminosity masks (and use them I suppose). I figured I would chime in a bit here with how I generate and use them in my own workflow. There is an older and interesting discussion about Luminosity Masks by Tom Kuyper that was referenced in that thread, and this is a translation of sorts for GIMP users that want to accomplish the same thing. The original tutorial by Tom is here: Tom Kuyper's Luminosity Masks Tutorial

The basic premise of luminosity masks is to allow you to modify elements of a layer masked to a specific region of luminosity (or value). If I wanted to control the colors in the shadows of my image without modifying the mid tones or light tones, then this is the method you want. Similarly you can adjust just the mid tones, or light tones without affecting the other regions as well.

If you are new to layer masks (or need to brush up), I recommend you head to Getting Around in GIMP - Layer Masks to brush up first, then come back.

Some Theory

What we'd like to accomplish is to produce masks for our image that target a specific tonal rage (lights, mids, or darks). This way, we can make adjustments to the image on a layer, and to use the masks to only apply those changes to certain areas (based on luminosity or value). The nice thing about using our image as the base for the mask is that the tonal ranges in the image will provide a smooth transition between the different layer masks.

Even though you may want to modify some aspect of the lighter portions of your image, it will be hard to tell where that effect is applied as it fades to a gray or black. Don't worry if this sounds strange, it will become clear before long...

To illustrate what we want, I am going to create a simple image with a gradient that goes from full white to full black:

Lights Mask

Now, across this gradient we may want to make modifications, but restrict them to the lighter values. This is usually the simplest mask to create, and just involves making a desaturated copy of your base image (based on Luminosity). So, create a copy of your base layer, and run:

Colors → Desaturate

and check the box for Luminosity.

After doing this, my gradient image will look exactly the same. I'll normally rename this layer to something original and creative, like Lights. That's actually all there is to it! Let's see it in action, though, to find out how this helps us.

I'm going to create a new layer in my image filled with red, and I am going to turn the visibility off on the other layers. So now my image looks like this:

At this point I will add a layer mask to my red layer by Right-Clicking on the red layer, and choosing Add Layer Mask.... I'll usually just initialize the mask to White (full opacity), because I'll be changing it shortly anyway.

Then I will want to copy my Lights layer by activating it (Left-Click on the layer), and then choosing:

Edit → Copy.

Now just paste this into the layer mask on the red layer by activating (Left-Clicking) the red layer mask, then doing:

Edit → Paste.

This will give you a Floating Selection (Pasted Layer) on your layer window, and you can just Right-Click the Floating Selection layer, and choosing Anchor Layer. This will now paste your Lights layer as a layer mask, and you should now see this:

My Layers palette now looks like this:

Basically, we can now change whatever we want on the red layer, and it will only affect the lighter parts of that layer.

Darks Mask

We can produce another mask that will only affect the darker parts of our image by simply inverting the Lights layer. First I'll duplicate the Lights layer, then invert the colors on that layer:

Colors → Invert

To keep things straight in my head, I'll find an even more original and interesting name to rename this layer, like Darks.

To show the two masks being applied to my image, I'll create another new layer below the red layer, and fill it with a nice blue, then add a layer mask, and copy-paste the Darks layer into the layer mask the same way as above.

This results in:

My layers palette for this image:

The reason that they are not perfectly blended exactly in the middle of the gradient is due to the layer ordering on my palette (red above blue). What we are seeing here is that the Lights and Darks layer masks only allow the portions of their layer to show through according to the mask (red shows through the Lights mask, and blue shows through on the Dark mask).

Mids Mask

There is one more mask we can make from these Light and Dark masks, and that is a mask for the Mid tones. This is simply the difference between the Light and Dark masks, inverted:

Lights Mask

Darks Mask

Mids Mask - Difference between Lights and Darks, inverted.

To create this mask easily, just make visible your Lights and Darks layer, then set the one on top (Darks in my example) to layer mode: Difference.

Right-Click on the top layer, and choose New from Visible. Then, invert the colors on the new layer (and name it something interesting... say... Mids).

Darks layer set to Difference mode, then created a new layer from visible, and inverted the new layer colors to get the Mids Mask.

If we now take our image strip one step further and add a green filled layer, and apply the Mids mask to it, we have this:

Solid Red, Green, and Blue layers with all masks applied.

The layers palette:

There is one other thing that bears mentioning here, and that is the range that each mask allows through. The Lights mask you will notice went from pure white, all the way to black, with many shades of gray in between. If you wanted one of your masks to not affect other tones as much, you can simply adjust the mask levels to remove other shades.

For instance, the red layer above the blue layer in the example above showed red extending past the mid tones and into the darker tones. You could clamp each mask to only affect from mid tones to either Light or Dark by adjusting each layer masks levels. You would basically activate a mask, then go to

Colors → Levels...

And set the Input Levels Black Point to 128 (middle gray). This will make the Lights mask stop affecting anything right at the middle gray point.

If you do the same thing to the Darks mask, then each mask will stop affecting anything right at the mid-point of values (they won't bleed over into each other). If I do this, and hide the green layer, we'll see:

Lights and Darks mask clamped at the mid point to prevent spill-over.

Layers palette:

The main thing to take away from this is that you can create these masks, and then narrow the range of tonal values they apply to by adjusting their range (using Levels). This can then let you filter out specific tonal ranges in your image to modify, independent of other areas.

A good example to see this in action would be to try some... Split Toning!

Split Toning

In my opinion, this is probably the easiest way to ease into how Luminosity Masks should work. The basic premise behind split toning is that you want to color a black and white image using two different colors: one color for the darks, and another color for the lights. In my example below, we'll use this image from the Dauphin Street Beer Festival in Mobile, AL.:

Conversation in Hayleys on Flickr (insert funny caption in the comments!)

You can download this image from my Flickr photostream if you'd like.

Now, we need to make some artistic judgements with how we want to split-tone this image. In honor of teal & orange madness, we will use a teal color to tint the dark areas of the image, and a nice orange for the lights.

With our newfound knowledge of how luminosity masks work, this should be a piece of cake, right?

Let's create those masks...

So load up your image, and duplicate the Background layer.
Desaturate it using Luminosity. This is now your base Lights layer (might want to rename it for clarity).
Duplicate this new Lights layer, and do Colors → Invert to invert it. This is your base Darks layer. Rename it to Darks
This step is optional, but if you wanted to clamp the Lights and Darks layers to not overlap, on each layer of the two layers do a Colors → Levels, and set the black points to 128 (see above).

You should now be looking at a layers palette that looks like this:

Now you have your Lights and Darks masks. The next step would be to add some color to your image. How you go about this is entirely up to you, but I will walk through a simple example.

Turn off all layers except your Background layer.
Copy your Background layer twice (we'll use one for the cool dark tones, and the other for warm light tones). Name them something descriptive (I'm going to use "Warm" and "Cool").

Now we need to tint each layer with the appropriate color. We'll start with the cool layer. You can tint this layer using any method you'd like, but for the purposes of this tutorial I'll use Colors → Colorize....
Your Cool layer should have a nice blue-ish tint to it right away (if you can't see it, you may have to hide any layers above it). Let's get it more teal-like by changing the Hue to about 200 in the Colorize the Image dialog:

Nice, but the entire image is now tinted teal. This is where we can apply the Darks layer mask to restrict the teal tint to the darker tones in the image only.
Add a layer mask to the Cool layer (Right-Click the layer, and choose Add Layer Mask... - you can initialize it to white, we're going to replace it in a moment.)
Select your Darks layer, and copy it (Edit → Copy).
Now select the Cool layer mask, and paste in the Darks layer you just copied. Right-Click the new Floating Selection (Pasted Layer) and Anchor Layer to apply it. Your image should now change, and you'll notice that the teal tint is only applied to the darker tones in your image.
Now on to the Warm layer! Select it, and again run Color → Colorize...
This time we want to use a warmer color for the light tones, so set the Hue to around 20. Your layer should have a nice orange-y tone to it.
Apply the Lights layer mask to the Warm layer. Right-Click the Warm layer, and choose Add Layer Mask..., again initializing to white is fine.
Select your Lights layer, and copy it (Edit → Copy).
Select the Warm layer mask, and paste in the Lights layer you just copied. Anchor the Floating Selection to apply it.

That's it! You should now notice that all the darker tones in your image have a cooler teal color to them, while the highlights will have a warm orange color. The separation of tones is all due to the Lights and Darks layer masks that you've applied:

Mouse over the image to see the original.

You could also go a step further here if you'd like and generate a Mid-tones mask as well for further experimentation! I know this has been long, but hopefully it's been helpful. I will write another post addressing how to further narrow the range of tones in your masks to specifically target even smaller sections of the image.

Feel free to ask any questions in the comments.

Getting Around in GIMP - Layer Masks

2011-10-05T12:28:00.000-05:00

An occasional question comes up concerning the use of Layer Masks for really controlling your edits to an image, and I thought I would approach the basics in this post. This is really a primer before moving into a much cooler topic - Luminosity Masks for controlling tonal ranges in a different way. (The Luminosity Masks tutorial is finished and can be found here!)

On a side note, this is also a method many people use for selective coloring an image. They will generate a desaturated version of their image, then lay a color version over it with a layer mask. You could then use the layer mask to only allow the color version to show where you painted it. (I am not a fan of selective coloring personally, but I'm not writing this post for me...)

The rest of my GIMP tutorials are all listed here: Getting Around in GIMP

Understanding Masks

First up is an understanding of how masks work in the first place.

Fundamentally, layer masks allow you to block out parts of the current layer that you want to show through. That's pretty much it. In GIMP, a white layer mask means that everything on that layer is visible. Any black in the layer mask will make that portion of your layer completely transparent, and will allow whatever is below to show through.

The power of layer masks is that the transparency of your layer can be controlled by any shade of gray. If you paint on a layer mask with 50% gray, then that portion of your layer will be 50% transparent (and it all scales linearly). Layer masks are purely grayscale affairs, so you can only work in shades of gray.

A quick example should illustrate things nicely here:

Believe it or not, he was sober when he posed for this...

Meet my friend Steven. (Shot as a test of my DIY ringflash during a party). Below the layer of Steven I have put another layer filled with orange. I've added a Layer Mask on the layer of Steven, and painted three sections on the Layer Mask (from top to bottom): White, 50% Gray, and Black:

And this is what it looks like as applied to the layer of Steven (remember, the orange layer is below the Steven layer):

And this is what my Layers window looks like at this point:

So as we can see, as the layer mask colors approach black, it makes the current layer more transparent to show what is below it.

I recommend you try this yourself to see what I mean. To add a layer mask to a layer, just Right-Click on the layer, and choose Add Layer Mask...
If you're just experimenting, you can just choose

Initialize Layer Mask to: White

to get started, this will make your entire layer opaque - then paint on black to choose what is transparent (or some other level of gray to control the amount of transparency).

Remember, the currently active layer (or mask) that you are operating on will have a white border in your Layers window (to select a different layer or mask to operate on, just Left Click on it).

Masks Example: Selective Coloring

To begin to see the power of using layer masks, we'll go through a simple example of Selective Coloring. Perhaps we'd like to have a black and white image of Steven, but only let his garishly red shirt color show...

In that case I would take my base image of Steven, and duplicate the layer of his image (Background in my case). You can duplicate a layer by Right-Clicking on it and choosing Duplicate Layer.

This will give you a new layer called Background copy. Now you can activate that layer by Left-Clicking on it, then turn it to black and white by choosing
Colors → Desaturate...
from the menus.

You can choose any method to choose the shade of gray (I'm partial to Luminosity most of the time). Then Right-Click on the Background copy layer and choose Add Layer Mask.... I chose to add a White layer mask for full opacity (meaning the layer is completely opaque).

After following these steps you should see your layers looking like this:

Color layer below, B&W layer on top with a white layer mask.

Now we are ready to bring out his shirt! Activate the layer mask by Left-Clicking on it, and choose a nice foreground color to paint with. Because we want his entire red shirt to show through, we'll choose black for maximum transparency. We basically want to paint in the area where his shirt is with black to make it transparent on this layer, and to allow the layer below to show through (the color layer).

I'm going to use a Paintbrush Tool with a big fuzzy circle to paint over his shirt with.

As you paint you should see that everywhere you paint the red shirt from the layer below comes popping through! After a quick painting session I've ended up with something like this:

The mask I painted looks like this:

Remember, I didn't have to use black as my painting color - if I had used a light gray, I would have let some of the color through, but not as much (leading to a more muted effect). Here is what the same thing looks like, but painted with a light gray instead of black:

The corresponding layer mask now looks like this:

Hopefully this has been a reasonable introduction to layer masks. That's really all there is to how they work. The power comes from manipulating the mask using other tools and approaches to really gain some amazing control over your image. In particular my next post will focus on creating and using luminosity masks to really control the tonal ranges in your images in a new way!

If you're ready for it, then head over to the next tutorial on how to start using these masks at Getting Around in GIMP - Luminosity Masks!

Young Frankenstein Minimalist Movie Poster

2011-09-28T14:07:00.001-05:00

Young Frankenstein Minimalist Movie Poster, a photo by avhell on Flickr.

My local independent movie theater the Crescent Theater in Mobile, AL is running a Shocktoberfest movie series of some great horror films. They just so happened to include one of my favorite films of all time in the list, Young Frankenstein!

Having seen some amazing minimalist movie poster art by other people got me thinking about this film, and trying to find a way to distill some iconic portions of the film into something instantly recognizable.

So I came up with these ideas very quickly, and knocked them out in Inkscape as vector graphics. I should probably leave this up to the professionals, but I had a good time playing with the ideas and laying these out!

Young Frankenstein Minimalist Movie Poster, a photo by avhell on Flickr.

While I love the top poster for what could be the funniest scene in the entire movie (I still lose it every time Peter Boyle sings...), the brain image feels like the most iconic for the entire movie. I mean, the entire movie is just the saga of Abby Normal, right?

Speaking of which, I went ahead and got the design setup and available on t-shirts and mugs (Abby Normal, that is) over at CafePress, so if you're interested in really showing off your love of the movie: Check it out here!

Getting Around in GIMP - Adjusting Levels

2011-07-21T15:09:00.001-05:00

The rest of my tutorials are here: Getting Around in GIMP

In my previous post on Color Correction, I outlined a method for finding the lightest and darkest values in an image using Colors → Threshold. What I may not have mentioned in that post was that the process described will actually level balance your images for you automatically if you follow the steps (choosing the darkest and lightest pixel values to represent black and white in your image).

If you were just interested in basic level adjustments, I thought I would cover that here.

Original image by Danielle Scott on Flickr.

Results of a basic level adjustment.

Original image by Alexis O'Toole on Flickr.

After a basic level adjustment.

What Level Adjustments will do is allow you to change where the brightest and darkest pixels in your image are. I say brightest/darkest because Levels will allow you to change the relative value of pixels across your image. (Color correction should be approached using other methods).

This means that you can control the brightest and darkest pixel values across your entire image using only the Levels slider, and you can adjust the gamma. If you don't adjust the middle level control, the response is linear across your image values. Let's have a look at the Levels dialog to clarify some items:

Input Levels - The range of values you want from the original image. The histogram represents the distribution of pixel values across your entire image from black (left) to white (right). There are three sliders just below the histogram. The far left slider adjusts where you want the darkest pixel values to be, the far right is the brightest pixel value location, and the middle slider is for gamma.

Output Levels - The range of values you want in your final image. The two sliders here are for the darkest and brightest values in your final output.

Auto, Pick Levels - The auto button, and the pick droppers for manually choosing where the different points should be in your image.

Adjustment via Sliders

Most of the time you will likely want a full range of values to be represented in your final image, so you will leave the output sliders set to the full range (0 - 255). You will make your adjustments entirely in the Input Levels portion of the dialog. You can approach this by using the histogram as a guide to where to set the sliders. The histogram is taller in places where there are a lot of pixels that represent that value. (For instance, if your image is overall very dark, the left side of the histogram will show taller than the rest).

Looking at my sample levels dialog image above, you can see that there doesn't appear to be many pixels at all in the darkest values. This is seen visually in an image as "washed out" blacks and dark values (this historgram is for the image of the trees and lane above). In this case you would grab the black point slider, and pull it to the right until you are approximately where the darkest values in your histogram begin. What you are doing here is "crushing" the darker pixels to black.

The same thing can be done for the brightest pixels by dragging the white point slider (far right) to the left. I normally leave the gamma alone unless it can produce good results. Usually it will wash out/crush the middle tones, but a slight bump in one direction or the other can sometimes help.

Adjustment via Manual Pick Points

This is a much more intuitive way of adjusting the levels in your image (and is the basis for my Color Correction tutorial). You will use the droppers to visually choose what should be the darkest/lightest/middle gray portions of your image.

The first button in this group is the "Auto" button. This will use GIMPs method of balancing the levels across your image, and will sometimes produce reasonable results. It doesn't hurt to try it as you can always undo it if you don't like it.

If it produces bad results or you just want more control, you can move on to the droppers. This is the method I will normally use most often if I'm playing with Levels only. The three droppers are for: Black Point, Middle Gray, and White Point respectively.

Each of the droppers work the same way. When you click on one, you activate it. Hovering your mouse over your current image should show your mouse pointer as an eyedropper tool. This means that wherever you pick in the image you are telling GIMP to make it either black, white, or middle gray (depending on which dropper you are using). GIMP will then adjust the levels in the image to match what you want.

If you have a point in your image that you either know is black (or want to be black), then click on the Black Point eyedropper, and click on the pixels in your image that should be black.

Now, by default, the picker will pick a sample from the pixel you choose, and will sample a radius around the pixel (3 by default I think). You can change the radius around the pixel to your liking by modifying the Radius under Sample Average in your Toolbox.

If you prefer single-pixel precision when setting a black/white/gray point, then simply un-check the Sample Average option in your toolbox. Now you can pick a single pixel to represent black/white/gray.

A final word on the gray point dropper, though. Usually you can easily find places on your photo where you expect a reasonable black or white value to be, and can easily use that as a pick point for the appropriate level. Middle gray is a little bit harder. You need to be sure that the pixels you are choosing really should represent middle gray in your image (RGB: 128 128 128). If they are not close, you will introduce a color cast in your image as GIMP will shift the RGB values to match middle gray where you pick!

How Polaroid Instant Film is Made

2011-07-12T09:00:00.000-05:00

Reading some feeds this morning and came across this interesting post at PetaPixel about how The Impossible Project produces instant film still (using an old Polaroid factory & equipment in the Netherlands). A really fascinating watch!

Getting Around in GIMP - Expired Polaroid 600 Film Effect

2011-06-27T11:38:00.004-05:00

I found an old Polaroid camera among a pile of old stuff in my house recently, and lo and behold it still had film in it! The camera had 7 shots left, and my wife and I had fun shooting the last few that evening. What was wonderful was that the developer/fix in the film had started to dry out (the film expired 5 years ago), and it left some wonderful un-developed portions of the final print where there was not enough chemicals to completely cover the image. The colors were also quite washed out and interesting.

Expired Polaroid 600 Scan, a photo by Pat David on Flickr.

Click here for my gallery on Flickr that shows some expired Polaroids to get an idea of the effect I am referring to.

For the rest of my tutorials on GIMP, see Getting Around in GIMP

So I have decided to attempt a replication of the effect in GIMP (mostly as a means to learn script-fu a little better). I have broken down the attempt at recreation into two parts:

Replicate the colors of the washed-out image, and the undeveloped portions of the print.
Replicate the border of the Polaroid 600 film to frame the image with, including the texture.

Replicating Colors

This wasn't as bad as I thought it would be. There are a couple of ways you could go about this...

One way is to open up a scan of an expired shot, and color correct it in GIMP until the colors look pretty good and natural to you. Then you will only need to find the RGB differences of some representative pixels to create your curve. I'll have a tutorial up later about how I approach that (tedious...).

Another way is to just go ahead and use the awesome Get Curves Plugin from elsamuko on GIMP registry. (By the way, I highly recommend checking out his other GIMP scripts/plugins as well!)

To use the script, you only need two layers in your image - the original, and the one you color-corrected to look more "normal". The original image should be above the "normal" one in your layer list. When you run the plug-in, it will generate a new GIMP curve file (called curve_SOME-DATE). The great thing about this plugin is that it checks pixel-by-pixel the color difference between the two layers, and creates the new curve from that data.

This curve now represents the color difference between your "normal" layer, and the original. You can now apply this curve back to the "normal" layer and the result should be really close to the original.

To help speed things along for anyone interested, I have already created the presets for my expired film:

Expired Polaroid 600 Curve Preset (the center strip)
Expired Polaroid 600 Run Curve Preset (the outer strips)

Save these files in your Curves folder for your GIMP install (locations vary, but you can check by going to Edit → Preferences and checking under Folders - it's usually around the same location as your brushes folder for instance).

Let's apply these curves to a new image to see the effect...

This is another image of my lovely model. I cropped the image to roughly match a Polaroid 600 image area (roughly 1:1.03 aspect ratio - the height is approximately 1.03 times the width).

Here the color curves linked above have been applied. I basically duplicated the base image twice, and applied each of the two color curves above to each duplicate. Then I used a layer mask to mask out the strip in the middle of different colors (allowing the layer below to show through). I still haven't added any grain or degraded pixel quality, but it seems fairly close!

If you've followed me this far - congratulations! As a bonus, I've already written the script-fu to automatically apply this to an image. It can be found at registry.gimp.org:

Download Expired Polaroid 600 Print Emulation script-fu

This script will also apply the un-developed corners that appear on expired film (usually because the developer has begun to dry up in the packets, and there is not enough to fully cover the frame anymore). To make things even more polaroid-y I have also removed any control over how big or where the undeveloped portions will occur. Just like real expired Polaroids! :)

Here's an example of the script in action (it doesn't create the border for you automatically - yet):

[Update]
There's a neat video here that shows how the Impossible Project is still cranking out instant film in the Netherlands.
[/Update]

Getting Around in GIMP - Muted Colors

2011-06-13T13:29:00.000-05:00

There seems to be a relatively recent interest in photo post-processing that is centered around recreating the look and feel of vintage photo elements. With the explosion of popularity around applications like instagr.am, quite a few photos have been showing up on Flickr and elsewhere that have these vintage types of effects applied to them.

Not surprisingly, this has led to an interest in photographers about how to achieve similar effects in their post processing workflow. In fact, more often than not I've noticed on the Flickr Photoshop Support Group questions pertaining to color toning/grading (especially prevalent are questions like "How do I do this?"). There are many ways to approach image color toning, and starting with something simple might help get people started.

In this post I want to talk about muting colors in an image. Below you'll find three different approaches to muting the colors in an image...

Original starting image.

Colors muted using a desaturated luminosity layer laid over the original with opacity.

Colors muted using layer masks and blending modes.

Colors muted using curves and blending modes.

I will provide a tutorial for using each of these different methods. The one you use is highly dependent on your subjective interpretations of what you want your final image to look like (and in some cases you may use more than one, and blend the result).

Desaturated Layer Method

This is the most straightforward and easiest method for desaturating the colors in your images. It basically consists of duplicating your layer, desaturating it (Colors → Desaturate), putting it above your full color layer, and changing the opacity of the desaturated layer to taste.

The step-by-step procedure is:

Create a duplicate layer of the color layer you want to mute.
Run Colors → Desaturate, and choose either Lightness, Luminosity, or Average (it's a personal preference - more detailed info can be found here).
Adjust the opacity of the desaturated layer to taste.

Layer Blend Modes Method

From Muted color effect, if you like that kind of stuff thread at the Photoshop Support Group on Flickr the user Tennessee_Gator describes an interesting method of muting colors using solid fill layers with masks applied to them. I had to do a little translation from the Photoshop-centric instructions, but I think I was finally able to replicate the same effect in GIMP.

There were two different methods of approaching this that I was working on, but thanks to some quick math by imagdoofus123 it turns out that both methods produce identical results, so I'll describe the easier of the two.

The basic idea is to use a luminosity copy of the color image, and to set two layers of this luminosity over your color image. One of the layers will be on a Multiply blending mode, and the other will be on Screen.

Create a duplicate of your color layer, and run Colors → Desaturate on it, using Luminosity.
Change the blending mode of this layer to Multiply.
Duplicate this Multiply layer, and change the new layer blending mode to Screen.

Color Curves Method

This method was mentioned in the discussion page linked to above as another possible approach (and allows for some more flexibility in tweaking the final results directly).

Duplicate your color layer, and set the blending mode of the new layer to Color.
Run Color → Curves...
Tweak an Inverted S-curve on the Value channel to taste.
Duplicate this layer, and set its blending mode to Value.
Run Color → Curves... again on this Value layer.
Modify the curve (slightly!) to a regular S-curve to adjust the contrast to taste.

These are just a couple of methods for desaturating an image, but I find them to cover most of what I need when doing this. As always, try experimenting with different layer opacity options to adjust the strength of the final effect. It's usually highly subjective just how much to mute, but the nice thing is that it's easy to vary the amounts with opacity and/or layer masks!

Easy Cheating Method (via my script)

If you've stuck with me this long (and you're a champ for reading all of this!), then I have one last little treat. I recently learned some quick script-fu to describe this to others on the GIMP users forum on Flickr - and it was just easier to go ahead and write a script to do the effect.

The script is called Muted Colors, and you can download it from the GIMP registry here.

You can choose any of the methods I've described above, with the exception of using curves. Hopefully some people find this helpful!

Bouncing Baby Beverly

2011-06-06T08:30:00.012-05:00

Bouncing Baby Beverly, a photo by avhell on Flickr.

Don't worry, no babies were harmed in the making of this photo (unless giggles count as harm). She was a really good sport, and just look at that smile!

I figure if I'm going to be taking hundreds of photos of her, might as well make some of them fun!

This was shot with a 20" softbox camera right, and some sunlight from a large covered window directly behind. I probably could have used a little more fill light from left, but I really like how it all turned out!

Update: I've put together a tutorial on how I shot this image, and Mike over at PetaPixel was kind enough to post it there, so check it out for more info!

PetaPixel - How to Make a Photo of a Bouncing Baby

Getting Around in GIMP - Color Correction

2011-06-03T15:33:00.007-05:00

The list of all my GIMP tutorials can be found here.

I've noticed that many people are interested these days in color processing effects for photos, and thought I'd share some interesting things to get people started on the path to color grading.

I almost always do some sort of color toning on my photos. Sometimes a little, sometimes quite a bit depending on my mood and vision at the time. I'm a big fan of just trying things out a bit to see where it gets me, and often this will change the course I may have been heading down into a completely new direction (I encourage this idea of playing around, especially in GIMP).

(This tutorial is a deeper look at a thread I originally started on the Flickr Gimp Users Group)

To begin, we should probably look briefly at balancing the colors in a photo to make sure we have a good base to start off with...

Basic Color Correction

Sometimes an image can come out of your camera looking either a little hazy or dull (possibly lacking contrast). So how can we get some "pop" back into the image? I will usually start by adjusting the overall range of the image to suit me.

What I mean by this, is that I want to identify the part of the image that will be pure black, pure white, and middle grey. So how can we do this? Well, a couple of ways...

Colors → Auto → White Balance

This method will let GIMP automatically calculate for you it's best estimate of what the white balance should be in the image. Sometimes this can produce OK results (and sometimes it can really mess up). I don't personally use this option, but if you want a no-frills first guess automated for you, it's a nice option to have.

I have also noticed that auto white balance can sometimes blow out highlights in an image as well...

Manual Balance

This is the method I have been using personally for a while now. The theory is basically that I want to identify where in the image I want the blackest blacks to be, the whitest whites, and a good middle grey point. So how can I find these quickly and easily in my photo?

Here's a hint: Colors → Threshold

Threshold will give you a means to see where the extreme pixel values for your image occur. With it we can identify where the brightest and darkest pixels are. The basic idea is to use a Threshold to isolate the brightest and darkest pixels in your image to set the white and black points, and to use a neat trick with a 50% gray difference layer to find the middle gray point.

So let's begin...

Image courtesy of Kelly Ealy - MM# 7866

Open an image you think could stand a little color correction.

Right click on the background layer and Duplicate Layer. This is the layer we will be working on fixing the color, and I'll call this the color correct layer.

With the color correct layer active (remember: white border around it), activate the Threshold dialog.

Colors → Threshold

Setting the White Point

We'll start by finding our white point in the image. The white point marker is already (be default) all the way to the right, and the black point marker is in the middle. What we'll do is pull the black point marker all the way to the right as well.

This should make the entire image show black (with possibly some white showing in places). What this means is that the white pixels, if showing, represent the brightest pixels in your image. If you don't see any white pixels yet, you can begin pulling the black point slider to the left slowly, and they will eventually begin to appear. You'll want to note the location of the first white pixels that begin to show up, and either remember them or use a sample point to save their location.

An important thing to remember here is that this is often a subjective determination of what you want to be pure white in your image. Some bright pixels (any RGB component is 255) will show up in threshold, even though they may not be "pure" white. Watch out for those, as a non-neutral color chosen to be your white point will cast a color on the entire image.

Cancel out of the Threshold dialog.

Now we want to use Colors → Levels to set the white point for our image to the pixels we identified with Threshold.

Open the levels dialog (Colors → Levels), and use the Pick White Point eyedropper to pick the location of the whitest pixels we just identified.

Hit OK to apply to the image. We basically just identified the location in our image we want to be pure white (255, 255, 255) in our final image.

Setting the Black Point

Now we can do the same procedure, but for the darkest/blackest point. Open the threshold dialog again (Colors → Threshold), and this time slide the black point slider all the way left, and do the same for the white point marker. The image should turn all black.

Slowly begin sliding the white point marker to the right until some white pixels begin to show up. These white pixels now represent the darkest pixel values in your image. As before, note their location (or use a sample point) and cancel out of the Threshold dialog.

Open the levels dialog again (Colors → Levels), and this time use the Pick Black Point eyedropper to pick the location of the darkest pixels we just identified.

Hit OK to apply to the image. We just identified where we want the blackest pixels in our image to be (0, 0, 0).

Setting the Gray Point

This one is a little tougher. You may not have an easily found truly neutral gray point (RGB 128, 128, 128) in your image. So we are going to use some layer blending modes to help us find the gray points closest.

Create a new layer above your color correct layer, and fill the layer with a neutral gray (RGB - 128, 128, 128).

Set the layer mode for this gray layer to Difference.

Right click on the layer in your Layers window, and choose New From Visible to create a new layer with what you can see. Make sure this new visible layer is the active one.

Now, run a threshold against this new layer.

Colors → Threshold

You will now follow the same procedure as you used for finding the black point threshold values, but in this case the white pixels will be those closest to Middle Gray.

Zoom into those first white pixels and remember where they are (or use a sample point).

De-activate the difference layer, and make your color correct layer active and visible. It helps if it is also the top-most visible layer (ie: turn off visibility on all layers above it in the Layers list).

Now use Colors → Levels again.

This time, use the Gray picker and choose the pixels you identified as closest to middle gray.

If you've chosen good points then the final result should be an image with much better looking color overall. If there was a nasty color cast previously, this method should remove it for the most part...

Here is my starting image, and after modification using this manual method:

It's subtle, but the original image was not in serious need of any balancing.

Mouseover the image below to see a comparison on an image where I didn't white balance properly before firing the shot (only modifications to the image were the manual color correction procedure):

Please feel free to post any comments/suggestions/rants in the comments if you get a chance to try this method out!

Getting Around in GIMP - New Layer

2011-05-25T12:29:00.002-05:00

Layers are really key to just about any workflow in GIMP. To help illustrate the concepts I am going to talk about, I've put together a quick screencast using Wink to show some steps of creating a new layer from scratch (please let me know if there is a problem viewing the screencast, it's my first time trying this).

The previous tutorial just covering the interface can be found here.
The list of all my GIMP tutorials can be found here.

One of the main things to remember when working with layers is that they will affect other layers from the top down in your layer list. I haven't mentioned layer blending modes yet, but for layers with a "Normal" blending mode (the default) this means that the top most layer that is visible is what you will see in your image window (see video).

Creating a new layer from scratch is quite simple. There is a "Create New Layer" button along the bottom of the top half of the Layers window. You will then get a "Create a New Layer" dialog that allows you to choose:

Layer Name
Whatever you want to call this layer
Width & Height
Dimensions for this new layer (default is the current image dimensions).
Layer Fill Type
You can have the layer automatically filled with either the foreground or background color, white, or start it as a transparent layer.

This new layer will then be created above the currently active layer in your list. Speaking of "active layer"...

Active Layer

The current active layer will have a white border around it in your layer list. This is important because it means that anything you do to the image will be applied to that active layer. If you activate a layer below another visible one, you may not see any changes you try to apply appear in your image window!

Look closely at the image above: the "Background" layer is active (white border), but there is another layer "New Layer" that is above it and visible. If you tried to paint or adjust the "Background" layer right now, you wouldn't see any of the changes (in fact, you'd just see a black screen in your image window).

To activate a layer, just click on it in your Layer Window list.

Visibility

You can toggle the visibility of each layer on/off by using the Eye icon to the left of the layer image. This will only affect the layer visibility in your main image window.

Very often I will use the layer visibility toggle to either compare a current layer to a previous one, or to show/hide the effects of a new layer on the ones below it (in the case of using a different blending mode or layer masks - which I will talk about shortly).

Getting Around in GIMP - The Interface

2011-05-24T13:53:00.003-05:00

I've found myself using GIMP more and more lately to manipulate photos, and thought that perhaps some of the things I've been playing with might be helpful for other users as well. Especially translations of effects that are achieved by photoshop users, but replicated for the GIMP environment. It is my hope to be able to provide some level of tutorials that might help others get as much use out of GIMP as I have.

The main list of all my GIMP tutorials can be found here.

To help others get the most from these tutorials and GIMP in general, I am starting out my first GIMP tutorial post by quickly examining the main interface in GIMP, and what all those floating windows mean...

GIMP users often seem to feel that the user interface is a barrier to entry for them. I agree that at first it can seem odd compared to the paradigm used by other programs, but I feel it's just a small sticking point. Spend a little time with it, and you will quickly get used to it.

In general, there will usually be 3 main (floating) windows that all of your work will be done in with GIMP:

Toolbox
Layers, Channels, Paths
Image Window

Toolbox Window

This window houses all of the tools available to you to manipulate your image. It may seem overwhelming at first glance, but you'll probably find that for the most part you only use a few different tools as you're getting started (a full list of each tool with shortcut keys and description can be found in the GIMP wikibook).

The window can be considered in two halves (upper and lower). Above the foreground/background colors are all the actual tools. Below that are modifiers for the currently selected tool (the Heal brush, in this case).

Some very common tools you will likely use often are:
Rectangle, Ellipse, Free Select
Bucket Fill, Gradient, Paintbrush
Clone, Heal

Just below the tool palette in the center of the window is the Color Area. This displays the current foreground (black in this example) and background (white) colors. You can swap between the foreground and background colors by clicking on the double arrow just above and to the right of the colors. Choosing a new color is easily done by just clicking on the current foreground or background color.

Below the Color Area are the available modifiers for the currently selected tool. What is shown here will change depending on the options available for the tool you select to use. In this image the Heal tool is active, and the options (Mode, Opacity, Brush, etc...) will apply to the Heal tool specifically.

Layers, Channels, Paths Window

This window displays all of the current layers in the image (including Channels and Paths). Realistically for the most part I personally use the Layers portion of this window more than any of the others.

Similar to the toolbox, this window can be divided into an upper and lower half.

The upper half is has tabs running across the top that give you access to (from left to right): Layers, Channels, Paths, and Undo history.

I will write up more detail on using Layers in image manipulation later (it deserves it's own post).

The lower half of this window shows access to three more tabs: Brushes, Patterns, and Gradients.

Image Window

This is where the magic happens. This window will display whatever image you happen to be editing. You'll also notice all of the menu items that are along the top edge of this window. These menus give you full access to all of the options that are available in GIMP (you can also access all of these menu items by right-clicking in the image area anywhere).

This should serve as a (brief) introduction to the basic GIMP user interface. Hopefully this will help some people feel just a tad more comfortable about getting around and where to find things.

I have further tutorials coming up on achieving some basic effects on photographs (and hopefully some more advanced ones as well). Stay tuned for more to come!

Seriously? A camera AND a softbox?!

2011-05-09T14:03:00.003-05:00

Seriously? A camera AND a softbox?!, originally uploaded by avhell.

Outtake from a quick Mothers Day shoot with little Beverly and her mom. Her expression is priceless.

She was a little on the squirmy side the entire time, and this annoyed look on her face made my day...

My ghetto 20" softbox with an FL-14 flash fired full power just to the camera left and a little high. About 2 feet away.

Beverly in Repose - Light Painted

2011-04-07T15:11:00.004-05:00

Beverly in Repose - Light Painted, originally uploaded by avhell.

Towards the end of the evening things start to quiet down. I have a few minutes to myself, and decide to grab my camera and a tiny little LED book reading light.

Tiptoeing into my daughters room, I wrap the legs of a gorrilapod holding my camera onto the edge of the crib and focus the camera. This is the only chance I'll have of painting light onto my little girl.

15 seconds of waving the little book light around madly produces this. A snapshot of the most perfect little person in the world.

Books and Prints for my daughter

2011-03-23T11:36:00.000-05:00

I am recently the proud parent of an absolutely amazing little baby girl. Her mother is a scientist, and I am an engineer - so when I came across this wonderful poster by Etsy artist electricboogaloo, we had to have it:

"Every baby knows the scientific method" by electricboogaloo on Etsy

While that is cute for mom and dad, a little something dad wants to share with his girl is more along the lines of these classic movie scenes interpreted as old "Little Golden Books" by Josh Cooley:

There's a whole bunch more of these here. Well worth a few minutes to peruse!

(via boingboing.net)

I (still) hate Comcast

2011-01-21T15:46:00.000-06:00

This just keeps getting sadder.

I finally did hear back from Mark Casem (who posted a comment on my earlier entry "I hate Comcast") and was told that he would look into the problem with my local Comcast guys. They did finally send someone out who determined that something was wrong with my line, and they sent a maintenance crew over to apparently fix it.

I say apparently because, well, have a look at my latest numbers (allow me to remind you that I am paying for 16 Mbps Business Class connection) for January 5 - 20:

And these are just the latest numbers since I last blogged about this problem. For comparison, the previous average from the last post was 3.1 Mbps. The current average as evidenced above shows an average now of 2.6 Mbps.

Not surprisingly, my latency has also gotten worse overall:

Previously, the average latency was 254ms, and now I am showing 297ms. I guess you can pretty much rule out any chance of playing an online game where latency matters (in fact, these ping times are closer to what I used to get playing Quake 2 on a dial-up connection!

I am trying to be understanding here, and as patient as possible. I have given them a couple of chances to come and fix this now, and things are only seeming to get worse. I will continue to call support while this speed is so abysmal with the hopes that they track this problem down and get it resolved ASAP (and I hope the billing department can help make this right for the lost bandwidth so far).

I just can't fathom the thought of a business having to deal with this type of sub-par performance for their internet. My recommendation at this point would be for any business even thinking about using Comcast as their internet provider is to NOT do it. DSL may be slower overall, but at least it's consistent and the bandwidth is all yours as opposed to a shared resource with your neighbors.

Just to keep things up to date, here is the total of my current averages from December 19 to yesterday (January 20):

Now I ask you, as a business paying for a 16 Mbps connection, does this even remotely seem reasonable?

I desperately want to say that this all gets fixed in a timely manner, but things are not looking good. Stay tuned for more as the story develops...

Firefly - Serenity HUD Display

2011-01-12T21:08:00.004-06:00

Firefly - Serenity HUD Display, originally uploaded by avhell.

I know that the use of a logo from the Weyland-Yutani corporation from the "Alien" franchise in this first episode of Firefly is old news, but on examining it again earlier today I noticed that the gun designation in the upper left corner of the HUD in this screen grab shows UA 571-D Ground Sentry. The name sounded familiar to me.

Upon investigation, it turns out I was right. In the extended version of "Aliens", there is a scene with automated remote sentries. The model of those remote sentry guns were UA 571-C.

A coincidence? I think not! Especially given Joss Whedons hand in the franchise... Still, I thought it was a pretty cool, if obscure, reference.

I hate Comcast

2011-01-05T10:29:00.001-06:00

Thanks to the speedtest.net iphone app, I have been monitoring my Comcast Business Class internet speeds and have been mighty upset with the results.

I had originally wanted DSL again, having had it for quite a few years and being quite happy with the performance and speed at the time. Unfortunately, upon moving into my new home I found that DSL couldn't get past 1.5 Mbps tops for me. So my only other option was to go with Comcast.

Now, I knew that cable internet was a shared resource locally, and I wanted to not have to worry about neighbors sucking down all the available bandwidth. So I figured I would go for the "Business Class" internet at 16 Mbps down even though the price was more expensive than the residential version. I figured that I could expect a better level of service since I was paying more for a business account.

WRONG.

Below are graphs of my internet speed performance for December 19th to now (blue line is download speed, red line is upload speed, and orange horizontal line is download average):

Despite paying more for a business class internet at 16 Mbps down, I have been seeing absolutely atrocious results. My average speed since the 19th of December has been 3.1 Mbps! Less than 1/5th of the advertised speed! They actually consider this "Business Class" service?! I feel bad for what the residential users nearby might have to deal with...

My ping latency is no better at all, and just plain depresses me. The average ping reported over the same time period was over 250ms! I haven't seen ping times like that since playing Quake 2 over dialup with friends over a decade ago.

The sad thing here is that the service used to be pretty ok. For two years they managed to at least deliver some semblance of service close to what they were advertising. Here's hoping that a few technical support calls will get someone out here to correct this ASAP. Stay tuned.

To settle matters, Pirates > Ninjas (Thanks Google!)

2010-12-31T15:18:00.003-06:00

Yes, it is a debate that has been raging for quite some time, but thanks to Googles book scanning and Ngram viewer, we have a new means of quantifying the Pirates vs. Ninjas debate. Behold:

That red line is Pirates trouncing Ninjas from Googles book scanning efforts! Of course, to make matters worse, we can compare some other fun things like:

Star Wars walking all over Trek (blasphemous some might say!).

And Love > Hate:

Head over to Google Labs Books Ngram Viewer and give it a try for yourself!

RIP Leslie Nielsen

2010-11-30T16:30:00.000-06:00

David Zucker remembers Leslie Nielsen in such a wonderful way.
From The Hollywood Reporter:

Arguably the best role was that of Dr. Rumack, played by the guy no one wanted or ever suspected would be funny, much less go on to have a second career starring in feature films as a goofball comic. Leslie was great in the role because he never "winked" -- let on that he knew he was in a comedy. This was essential to the style, and Leslie had a natural instinct for it.

One of my all-time favorite exchanges in film:

Rumack: Captain, how soon can you land?
Captain Oveur: I can't tell.
Rumack: You can tell me. I'm a doctor.
Captain Oveur: No. I mean I'm just not sure.
Rumack: Well, can't you take a guess?
Captain Oveur: Well, not for another two hours.
Rumack: You can't take a guess for another two hours?

Scott Adams learns to follow directions

2010-11-11T14:51:00.000-06:00

Dilbert's Scott Adams has the best explanation for why to wear gloves when cutting jalepeno peppers...

Imagine turning a broom upside down, so the pointy bristles are facing up. You take your hand, palm facing down, and bounce it on the pointy bristles. Can you imagine how uncomfortable that feels on your hand? Okay, good.

Now imagine that a giant troll sees you playing with the broom. He snatches it out of your hand, chews the handle into a point and shoves it so far up your ass that you can taste it. Then he uses you like a huge flyswatter to kill a nest of porcupines that are living in his salt mine. My hand hurt like that.

From his night he learned to follow directions...

Iphone 4 (iOS 4.1) Video Upload Quality Test

2010-10-05T16:27:00.002-05:00

I recently became the new owner of a iPhone 4 after beating my old 3G phone to within inches of its life (not on purpose, just the normal wear and tear sort of life-beating). I had originally dropped my phone last week from my night table, and it left the display looking like it was super-saturated with mega-brightness. I fiddled with the brightness settings and smacked it around a bit, but all to no avail. I figured a broken phone was as good a reason as any to upgrade. Of course, in a bout of madness I decided to try one last thing before I gave it up as a lost cause, and opened my phone up where I found that the LCD connection ribbon had jostled loose: all it took to cure the phones problems was to re-seat the connector.

Stupid, itchy gadget lust...

Of course, by that time I was already more than halfway to resigning myself to an upgrade. It didn't help things that my wife was also interested in getting a new phone.

One of the main draws for me besides the snappier processor and new hardware, was the improved camera and ability to record 720p HD video. I had read in other places online, though, that there were problems with uploading the full resolution video to YouTube directly from the phone. To test what was going on, I have tried a few things and these are my results.

The Source

The source material is just a quick pan of the parking lot at my work. It's interesting in that there are many trees in the background that can often tax HD video in capturing properly. If you want the original quicktime file directly off the phone, it's here:

Original .MOV from the camera (12MB)

Direct upload from the iPhone

I then uploaded this video to YouTube in two ways:

First, as a direct upload from the camera using the "Send to YouTube" button:

Upload using "Send to YouTube"

After choosing to upload in HD, this starts what I believe to be a transcoding process where the video is shrunk in size in preparation for upload.

Preparing Video... (I suspect transcoding at this point)

After "Preparing Video..." the actual upload starts, and when finished I am prompted to go to YouTube or to "tell a friend".

The final directly uploaded from the iPhone video is here (don't forget to change it to 720p):

Transfer to computer, then upload

In this case, I just plugged my iPhone directly into my computer and copied the .MOV file onto my desktop. From there I just uploaded to YouTube as I would for any other video file. The final uploaded from my computer:

Screen grab comparison

This is where things get interesting. I've grabbed a screen cap of each of the videos at the same moment in time. I basically downloaded the .mp4 from YouTube for the two uploaded videos, and used MPlayer to output a screen capture at the same frame.

Below are the three screenshots (click to open the full size image) I am using here:

Original .MOV directly from the phone

Uploaded from computer

Uploaded directly from iPhone

The Crops

Using these screenshots, I then crop and zoom into 300% size to investigate the results of a small sub-section of the image.

Original from camera (left), after upload from computer to YouTube (center), after direct upload from phone to YouTube (right).

In this first crop of the light pole, some things become evident almost immediately. The colors and detail in the shadow areas of the image are devastated by the compression going on. The direct upload from my computer to YouTube at least manages to keep some of the details, but the direct upload from the phone smears all of the detail of the background foliage, especially around the lamppost. It also appears that the colors are reduced or muted in the direct upload compared to the other two methods.

Original from camera (left), after upload from computer to YouTube (center), after direct upload from phone to YouTube (right).

In the crop of the parking lot there are some other telling things going on. The first thing I notice is the desaturation of the colors in the handicap parking sign for the direct upload. The upload from computer manages to retain the colors, and a lot of the detail of the sign, but the direct upload sadly does not. Also notice the shadows in the tree in the upper left corner where for both versions YouTube manages to smear it all into a mess.

Original from camera (left), after upload from computer to YouTube (center), after direct upload from phone to YouTube (right).

In this final crop, the telling problems occur again in the shadows of the foliage, where it gets progressively worse from the original to a direct upload. Notice the loss of detail in the definition of the leaves, and especially in the mulch (brown) on the ground in the middle distance.

Conclusion

From what I have seen I feel that what is happening is that the successive degradation of the video quality is due to having to transcode the video twice during a direct upload from the iPhone, as opposed to only transcoding once with an upload from my computer. As with any transcoding, the quality begins to suffer horribly after the first time. In this case, the color saturation and especially the shadow details are lost very quickly during the second transcoding as is the case with the direct upload from the iPhone.

In a pinch I feel that a direct upload could do and be passable for some simple video. If it was something I wanted to keep a little quality on, and I could wait until I was at a computer, I would rather just upload directly from my computer and avoid the extra transcoding step that hurts the quality so badly.

Quick and Easy Visualization of Paint Colors for Rooms

2010-09-14T16:39:00.000-05:00

I have recently completed the major stages of renovation for a Florida room in my home. All the old paint and wall surfaces were torn down and built back up to what we wanted as a finish, and we were staring at a fully primed, and waiting for paint, empty room. The only problem was, we hadn't really decided on a color scheme yet!

I needed a quick way to visualize what general types of colors we thought we'd like to use, so I came up with a way using my camera and GIMP. I will outline the steps I used below, with some example photos taken from Flickr. The nice thing about this approach is that you can visualize just about any room with new paint even if the room is not empty, and even if there are different lighting conditions across walls (sun shining in a window, while another wall might be in shadow for instance).

So to explain, I am using Flickr user micamica's living room photo:

The basic process here will be to isolate the walls we are interested in changing the color of, and to then adjust the colors of that wall to help us visualize what the room will look like.
After loading the image up in GIMP, I will often duplicate the Background layer right away (so I always have a version of the original available later). After that it's time to start isolating the wall we want to change the color of. In this case, I want to consider changing the large rear wall with the painting hanging on it, but will leave the low wall behind the couch to either keep it white or to change it to a different color than the main wall.

There are a couple of ways to select just the wall we want in GIMP. If we just want a quick visualization to get an idea of what the color will feel like in the room, we can make use a "Quick Mask" in GIMP to quickly paint in the areas we want to select. The toggle to turn on Quick Mask is on the bottom left of the GIMP screen, and looks like a small red square. When you turn it on, your entire image will appear to have an opaque red layer over everything.

To select the areas we are interested in, just paint over the area you want with a white color. I like to use a fuzzy circle brush to allow the edges to feather just a bit. You will want to paint in all of the areas you want selected. As you paint, the opaque red mask will disappear and show the image underneath:

Quick masked wall (note art left not selected)

Toggling quick mask leaves a selection of just the wall

After you've painted out your selection, toggle the Quick Mask again, and you're left with a selection of what you painted. At this point, you can quickly try changing the color of the wall. First, though, I personally like to do this without having the "marching ants" selection showing to distract me. To turn them off in GIMP, go to View -> Show Selection, and uncheck it (don't worry, you're selection is still active - just don't forget that it's hidden or you're gonna be cursing when paintbrushes don't work right for some reason).

Now you're ready to adjust some colors! Go to Colors -> Hue-Saturation. You can now adjust the sliders for the Hue and Saturation to adjust what your selected wall will look like. For instance, what about a nice soothing blue color?

Another option would be to use GIMPs "Colorize" command under Colors -> Colorize. Again, adjust the Hue to your liking, and tweak the Saturation and Lightness to taste. In this case, a deeper red color:

If you wanted to adjust colors of other sections of the photo, you can always save your current selection to a channel for recall later on. Just use Select -> Save to Channel, and your current selection will be saved to a channel (mine is saved as "Selection Mask Copy" by default). You can now quick mask a different portion of your image, and repeat the above steps to apply a different color.

In the above steps, I am just roughly trying to quickly visualize a different set of colors on a room to get a feel for it, so this is by no means a detailed and meticulous modification. You could spend a lot more time masking out portions of your image more carefully if you wanted something a bit better. For images that have walls that are already colored, you could also run a "Desaturate" on your selection before using "Colorize". This will remove any colors already present on the wall, but still keep the shading and relative shadows.

This method is not perfect, but certainly serves nicely to quickly visualize what type of colors might be more interesting to pursue for the room!