tag:blogger.com,1999:blog-85231147312850438912024-11-01T04:08:07.667-07:00All purposes blog (programming, ect ...)Cyril Yomihttp://www.blogger.com/profile/01414384071897949120noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-8523114731285043891.post-88019902136184831982010-04-01T21:41:00.000-07:002010-04-04T13:41:21.781-07:00The purpose of this code is to implement an image processing filter using the filter matrix (with vb.net) I use as document the filter chapter of the GIMP documentation. (GIMP is actually the tool I usually use for some assignments in the webdesign).<br />here is the link: <a href="http://docs.gimp.org/en/plug-in-convmatrix.html">http://docs.gimp.org/en/plug-in-convmatrix.html</a><br /><br />so it's actually not too difficult to implement. here the code:<br /><br />'get the library<br />Imports System.Drawing.Bitmap<br /><br />...<br /><br />' Create a Bitmap object from a file.<br />Dim myBitmap As New Bitmap ("imagepath") ' example ("C:\whatever\ ...")<br />' Create a bitmap object result<br />Dim mybmpResult As Bitmap<br /><br />'set kernel matrix (this very one is an edge detector)<br />'you can change the values to obtain a blur effect, or sharpen or whatever<br />'check the kernel values in the link<br /><br /> Dim k11, k12, k13, k21, k22, k23, k31, k32, k33 As Double<br /><br /> k11 = 0<br /> k12 = -1<br /> k13 = 0<br /> k21 = -1<br /> k22 = 3 'here I use 3 instead of 4<br /> k23 = -1<br /> k31 = 0<br /> k32 = -1<br /> k33 = 0<br /><br />'Now it's actually a simple matrix calculation of the pixels in 2 loops<br />'You can check the link to see how it s done.<br /><br />Dim Ycount As Integer<br /> For Ycount = 1 To myBitmap.Height - 2<br /><br /> Dim Xcount As Integer<br /><br /> For Xcount = 1 To myBitmap.Width - 2<br /><br />'you need 9 matrix elements, and for each of those,<br />'you need the RED, GREEN AND BLUE value<br />'to form 1 pixel<br /><br />'values of first row in RGB<br /> Dim x11R, x12R, x13R As Integer<br /> Dim x11G, x12G, x13G As Integer<br /> Dim x11B, x12B, x13B As Integer<br /><br />'values of second row in RGB<br /> Dim x21R, x22R, x23R As Integer<br /> Dim x21G, x22G, x23G As Integer<br /> Dim x21B, x22B, x23B As Integer<br /><br />'values of third row in RGB<br /> Dim x31R, x32R, x33R As Integer<br /> Dim x31G, x32G, x33G As Integer<br /> Dim x31B, x32B, x33B As Integer<br /><br />'assign all those values according to the bitmap object<br /><br /> x11R = myBitmap.GetPixel(Xcount - 1, Ycount - 1).R<br /> x11G = myBitmap.GetPixel(Xcount - 1, Ycount - 1).G<br /> x11B = myBitmap.GetPixel(Xcount - 1, Ycount - 1).B<br /><br /> x12R = myBitmap.GetPixel(Xcount, Ycount - 1).R<br /> x12G = myBitmap.GetPixel(Xcount, Ycount - 1).G<br /> x12B = myBitmap.GetPixel(Xcount, Ycount - 1).B<br /><br /> x13R = myBitmap.GetPixel(Xcount + 1, Ycount - 1).R<br /> x13G = myBitmap.GetPixel(Xcount + 1, Ycount - 1).G<br /> x13B = myBitmap.GetPixel(Xcount + 1, Ycount - 1).B<br /><br /> '---<br /><br /> x21R = myBitmap.GetPixel(Xcount - 1, Ycount).R<br /> x21G = myBitmap.GetPixel(Xcount - 1, Ycount).G<br /> x21B = myBitmap.GetPixel(Xcount - 1, Ycount).B<br /><br /> x22R = myBitmap.GetPixel(Xcount, Ycount).R<br /> x22G = myBitmap.GetPixel(Xcount, Ycount).G<br /> x22B = myBitmap.GetPixel(Xcount, Ycount).B<br /><br /> x23R = myBitmap.GetPixel(Xcount + 1, Ycount).R<br /> x23G = myBitmap.GetPixel(Xcount + 1, Ycount).G<br /> x23B = myBitmap.GetPixel(Xcount + 1, Ycount).B<br /><br /> '---<br /><br /> x31R = myBitmap.GetPixel(Xcount - 1, Ycount + 1).R<br /> x31G = myBitmap.GetPixel(Xcount - 1, Ycount + 1).G<br /> x31B = myBitmap.GetPixel(Xcount - 1, Ycount + 1).B<br /><br /> x32R = myBitmap.GetPixel(Xcount, Ycount + 1).R<br /> x32G = myBitmap.GetPixel(Xcount, Ycount + 1).G<br /> x32B = myBitmap.GetPixel(Xcount, Ycount + 1).B<br /><br /> x33R = myBitmap.GetPixel(Xcount + 1, Ycount + 1).R<br /> x33G = myBitmap.GetPixel(Xcount + 1, Ycount + 1).G<br /> x33B = myBitmap.GetPixel(Xcount + 1, Ycount + 1).B<br /><br />'matrix calculation of R<br /> x22R = (x11R * k11 + x12R * k21 + x13R * k31) + (x21R * k12 + x22R * k22 + x23R * k32) + (x31R * k13 + x32R * k23 + x33R * k33)<br /><br /><br />'matrix calculation of G<br /> x22G = (x11G * k11 + x12G * k21 + x13G * k31) + (x21G * k12 + x22G * k22 + x23G * k32) + (x31G * k13 + x32G * k23 + x33G * k33)<br /><br /><br />'matrix calculation of B<br /> x22B = (x11B * k11 + x12B * k21 + x13B * k31) + (x21B * k12 + x22B * k22 + x23B * k32) + (x31B * k13 + x32B * k23 + x33B * k33)<br /><br />'if it happens, that the calculation result is negativ or greater than 255, then<br />'keep it in the range<br /><br /> If x22R < 0 Then<br /><br /> x22R = 0<br /><br /> End If<br /><br /> If x22R > 255 Then<br /><br /> x22R = 255<br /><br /> End If<br /><br /> If x22G < 0 Then<br /><br /> x22G = 0<br /><br /> End If<br /><br /> If x22G > 255 Then<br /><br /> x22G = 255<br /><br /> End If<br /><br /> If x22B < 0 Then<br /><br /> x22B = 0<br /><br /> End If<br /><br /> If x22B > 255 Then<br /><br /> x22B = 255<br /><br /> End If<br /><br />'then for each pixel result, set the result in the new bitmap object<br /><br /> mybmpResult.SetPixel(Xcount - 1, Ycount, Color.FromArgb(x22R, x22G, x22B))<br /><br /> '#############################################<br /><br /> Next Xcount<br /> Next Ycount<br /><br />'You can also view the result in a pictureBox, you just drag and drop in visual basic, and then<br />PictureBox1.Image = mybmpCyril Yomihttp://www.blogger.com/profile/01414384071897949120noreply@blogger.com