Image Formats Information

Bmp Image Format

noreply@blogger.com (Image Formats) — Sun, 10 Oct 2010 03:54:00 +0000

BITMAP Image Format

The BMP image file also called DIB image file. DIB means (Device Independent Bitmap). It is an image file used to store image data with different bit levels. This article describes the BITMAP file formats used in Microsoft windows, and IBM os/2 machines in byte by byte level. Its file extension is either BMP or DIB. The sample 24 bit BMP and DIP image are shown below.

Sample Bitmap.dip

Sample Bitmap.bmp

Contents :

DIM or BMP Image file format
Bitmap File Header

Bitmap File Header Field details

Bitmap Information

Bitmap Information Field details

Color Palette

Color Palette Field details

Bitmap Data

Bitmap Data Field details

DIM or BMP Image file format:

A typical BMP has the following structure. It consist if BMP File Header, Bitmap Information, Color palette and Bitmap Data.

BMP File Header	BMP file general information.
Bitmap Information (DIB header)	Detailed information about the BMP image.
Color Palette	Color definitions used for indexed color bitmaps.
Bitmap Data	pixel by pixel image data

To explain the information in details, the above bmp image is taken as a sample image and its hex values are displayed.

Bitmap File Header:

For any file types first few bytes are identify of that files. It identifies the file types. Like that here also first two bytes are the identity bytes. Generally first two bytes has the value of 'BM'. All the values are stores in little-endian encoding format. Generally the first 14 bytes contains the BMP file header information.

Offset	Size	Purpose
0000_h	2 bytes	BM – Windows 3.1x, 95, NT, ... etc. BA – OS/2 Bitmap Array CI – OS/2 Color Icon CP – OS/2 Color Pointer IC – OS/2 Icon PT – OS/2 Pointer
0002_h	4 bytes	BMP file size in bytes
0006_h	2 bytes	reserved
0008_h	2 bytes	reserved
000A_h	4 bytes	the offset, i.e. starting address, of the byte where the bitmap data can be found.

Bitmap File Header Field details:

Identifier:
From the sample image. The first two bytes are the identity bytes so it's 'B' and 'M'.

File Size:

The Image size is 47174 bytes (refer size.png). 47174 equvalent of hex value is B846. The image representation is little-endian so the value becomes 05 th byte = 00, 04 th byte = 00, 03rd byte = B8, 02 nd byte = 46.

Reserved: Bytes 6,7,8 and 9 are reserved so its value will be zero

Offset : Starting address of bitmap data. I.e the starting address of the bitmap data. In the sample image it is 36 (Represented in byte 0Ah) because it does have any extra color palate data or header information so it would be 36.

Bitmap Information (DIB header):

The header bytes show the detailed information of BMP image. Here I am giving five versions of header two from IBM OS 2 versions and three from Microsoft versions. Because Microsoft extended the DIB format several times. So that the new header format is used instead of the older ones for providing more functionality. Since windows GDI loads the bitmap file into the system.

Size	Header	Identified by	Supported by the GDI of
12	OS/2 V1	BITMAPCOREHEADER	OS/2 and Windows 3.0 and above
64	OS/2 V2	BITMAPCOREHEADER2
40	Windows V3	BITMAPINFOHEADER	Windows 3.0 and above
108	Windows V4	BITMAPV4HEADER	Windows 95/NT4 and above
124	Windows V5	BITMAPV5HEADER	Windows 98/2000 and above

The table has all the five formats of header information’s. From the size of the header system identifies which version of header is used. The header size is in offset 0Eh.

BITMAPCOREHEADER or OS/2 V1 Header Structure

This structure is used in all OS/2 and also all Windows versions since Windows 3.0. This is a simple structure its size is 12 bytes. It has size, width, height, planes and bitcount. The offset and byte values are shown in the following table. This is also called as OS/2 V1 bitmaps. This format does not use any compression algorithms and it does not have 16 or 32 bit depths. The values in the header are unsigned integers. 32 bit version with alpha channel is introduced in Windows XP and it is used for its login screen. It is supported by Adobe Photoshop version 7 and above, Adobe flash and GIMP

Offset	Size	Purpose
Eh	4	size of the header (12 bytes)
12h	2	bitmap width in pixels.
14h	2	bitmap height in pixels.
16h	2	the number of color planes; 1 is the only legal value
18h	2	the number of bits per pixel. Typical values are 1, 4, 8 and 24.

The typical structure used here is

typedef struct tagBITMAPCOREHEADER {
  DWORD bcSize;
  WORD bcWidth;
  WORD bcHeight;
  WORD bcPlanes;
  WORD bcBitCount;
} BITMAPCOREHEADER, *PBITMAPCOREHEADER;

BITMAPCOREHEADER2 or OS/2 V2 Header Structure

This version has few additional fields over BITMAPINFOHEADER. The BITMAPINFOHEADER header info is given below. This is also called OS/2 V2 header used in IBM OS/2 Versions. Its header size would be 64 bytes. The typical C structure is given below.

typedef struct {
   DWORD bc2Size;
   DWORD bc2Width;
   DWORD bc2Height;
   WORD bc2Planes;
   WORD bc2BitCount;
   DWORD bc2Compression;
   DWORD bc2SizeImage;
   DWORD bc2XRes;
   DWORD bc2YRes;
   DWORD bc2ClrUsed;
   DWORD bc2ClrImportant;
   /* same as BITMAPINFOHEADER until this point */
   WORD bc2ResUnit;
   WORD bc2Reserved;
   WORD bc2Orientation;
   WORD bc2Halftoning;
   DWORD bc2HalftoneSize1;
   DWORD bc2HalftoneSize2;
   DWORD bc2ColorSpace;
   DWORD bc2AppData;
} BITMAPCOREHEADER2;

BITMAPINFOHEADER Header Structure:

All Windows versions since Windows 3.0 uses this header format. Its size is 40 bytes. For compatibility reason almost all versions of OS uses this header format. It has all the information generally used. All values are unsigned integers.

Offset #	Size	Purpose
0Eh	4	size of the header (40 bytes)
12h	4	bitmap width in pixels (signed integer).
16h	4	bitmap height in pixels (signed integer).
1Ah	2	number of color planes being used. Must be set to 1.
1Ch	2	the number of bits per pixel, I.e color depth of the image. Values are 1, 4, 8, 16, 24 and 32.
1Eh	4	compression method being used.
22h	4	image size. This is the size of the raw bitmap data (0 for BI_RGB bitmaps), and should not be confused with the file size.
26h	4	horizontal resolution of the image. (pixel per meter, signed integer)
2Ah	4	vertical resolution of the image. (pixel per meter, signed integer)
2Eh	4	number of colors in the color palette, or 0 to default to 2ⁿ.
32h	4	number of important colors used, or 0 when every color is important; generally ignored.

The sample image has BITMAPINFOHEADER header which is shown in the following image. Verify the offset 0Eh to 11h value would be 26h (=40 in decimal).

typedef struct {
  uint32_t header_sz;
  int32_t width;
  int32_t height;
  uint16_t nplanes;
  uint16_t bitspp;
  uint32_t compress_type;
  uint32_t bmp_bytesz;
  int32_t hres;
  int32_t vres;
  uint32_t ncolors;
  uint32_t nimpcolors;
} bmp_dib_v3_header_t;

Bitmap Compression Methods.

The following compression methods are used in BMP Image which are shown in the following table.

Value	Meaning
BI_RGB	An uncompressed format.
BI_RLE8	RLE compression format for bitmaps with 8 bpp. The compression format is a two-byte format consisting of a count byte followed by a byte containing a color index. If bV5Compression is BI_RGB and the bV5BitCountmember is 16, 24, or 32, the bitmap array specifies the actual intensities of blue, green, and red rather than using color table indexes.
BI_RLE4	RLE compression format for bitmaps with 4 bpp. The compression format is a two-byte format consisting of a count byte followed by two word-length color indexes.
BI_BITFIELDS	Specifies that the bitmap is not compressed and that the color table consists of three DWORD color masks that specify the red, green, and blue components of each pixel. Valid when used with 16- and 32-bpp bitmaps.
BI_JPEG	JPEG Compression is used. It can achieve a compression ratio of 20:1 with little noticeable loss.
BI_PNG	PNG file Interchange Format compression.

typedef enum {
  BI_RGB = 0,
  BI_RLE8,
  BI_RLE4,
  BI_BITFIELDS,
  BI_JPEG,
  BI_PNG,
} bmp_compression_method_t;

BITMAPV4HEADER Structure:

The BITMAPV4HEADER structure is an extended version of the BITMAPINFOHEADER structure. This header size is 108 bytes. It is supported by Windows 95/NT4 and above. The C structure for this header is

typedef struct {
  DWORD bV4Size;
  LONG bV4Width;
  LONG bV4Height;
  WORD bV4Planes;
  WORD bV4BitCount;
  DWORD bV4V4Compression;
  DWORD bV4SizeImage;
  LONG bV4XPelsPerMeter;
  LONG bV4YPelsPerMeter;
  DWORD bV4ClrUsed;
  DWORD bV4ClrImportant;
  DWORD bV4RedMask;
  DWORD bV4GreenMask;
  DWORD bV4BlueMask;
  DWORD bV4AlphaMask;
  DWORD bV4CSType;
  CIEXYZTRIPLE bV4Endpoints;
  DWORD bV4GammaRed;
  DWORD bV4GammaGreen;
  DWORD bV4GammaBlue;
} BITMAPV4HEADER, *PBITMAPV4HEADER;

refer : http://msdn.microsoft.com/en-us/library/dd183380(VS.85).aspx for more about BITMAPV4HEADER Structure.

BITMAPV5HEADER Structure:

The BITMAPV4HEADER structure is also an extended version of the BITMAPINFOHEADER structure. This header size is 124 bytes. It is supported by Windows 98/2000 and above. The C structure for this header is

typedef struct {
  DWORD bV5Size;
  LONG bV5Width;
  LONG bV5Height;
  WORD bV5Planes;
  WORD bV5BitCount;
  DWORD bV5Compression;
  DWORD bV5SizeImage;
  LONG bV5XPelsPerMeter;
  LONG bV5YPelsPerMeter;
  DWORD bV5ClrUsed;
  DWORD bV5ClrImportant;
  DWORD bV5RedMask;
  DWORD bV5GreenMask;
  DWORD bV5BlueMask;
  DWORD bV5AlphaMask;
  DWORD bV5CSType;
  CIEXYZTRIPLE bV5Endpoints;
  DWORD bV5GammaRed;
  DWORD bV5GammaGreen;
  DWORD bV5GammaBlue;
  DWORD bV5Intent;
  DWORD bV5ProfileData;
  DWORD bV5ProfileSize;
  DWORD bV5Reserved;
} BITMAPV5HEADER, *PBITMAPV5HEADER;

refer : http://msdn.microsoft.com/en-us/library/dd183381(VS.85).aspx for more about BITMAPV5HEADER Structure.

Internet connection through mobile

noreply@blogger.com (Image Formats) — Tue, 18 May 2010 04:22:00 +0000

Introduction:

Present world covered by technology. Today every person have mobile phone and some person have Personal computer for their own use. Can we connect internet service to your personal computer through mobile phone?. Yes today it is possible. This blogspot will expain how to connect between PC and mobile for internet use.

About GPRS connection:

General packet radio service (GPRS) is a packet oriented mobile data service available to users of the 2G cellular communication systems global system for mobile communications (GSM), as well as in the 3G systems. In 2G systems, GPRS provides data rates of 56-115 kbit/s.

GPRS Service provider in Tamilnadu circle: Aircel, Airtel, BSNL, Reliance, Vodafone, etc.,

How to connect?

I would like to give some steps to make a internet connction.

Step 1: First you have to check your mobile web option is available or not?
Incase this mobile web option is not available in your mobile, you can not make GPRS connection.

Step 2: Just call to your mobile service provider to activate GPRS connection. Then they will send GPRS setup to your mobile phone.

Step 3: After saved your mobile setup,just check up GPRS connections is working properly in your mobile.

Step 4: Install your PC suite software to your PC. This PC suite comes with your new mobile. If you don't have PC suite software, just go to your mobile maker website. Then download your PC suite according to your mobile model.

Step 5: Two options are there to connect from Mobile to computer.
Option 1: connecting through mobile data cable
Option 2: connecting through Bluetooth device

Note: After connect your mobile to PC, you Mobile will act as Modem.

Step 6: You have to create new network connection in your Personal computer. Then ask to your service provider to setup new modem.

Step 7: Finally start your browser in your PC.

Example:

Mobile model: Sony ericsson W350i

Mobile to pc internet connection for sony ericssion mobile.

It is very esay if you are use sony ericsson mobiles. First install your mobile PC suite to PC . PC suite means, it is like as a software, This software CD has been given to you when you bought new mobile.

In case you do not have PC suite CD. download the appropriate sony ericsson pc suite for your mobile model from sony ericsson web site(http://www.sonyericsson.com/cws/support/phones/w350i?cc=gb&lc=en).

After installing the pc suite in your PC, then run PC suite software. As far as Sony ericsson is concern, do not need to create any new network connection in your PC. This Sony PC suite have small option to create new network connection. This option is located below the PC and web logo in PC suite software. click that option then make a network connection.

Connect your phone to the PC with data card. mobile phone asks the connection type choose phone mode as the connection type in the mobile.

Select internet connect in the left side of menu panel.

Then press connect in the first time it asks country, region etc.. give appropriate values then go next, next etc. You must give APN (Access Point Name) correctly. Otherwise you can not make any connection in your PC. For example, if you are using Aircel give APN as aircelgprs.pr for other networks the apn is available in the mobile internet settings. then press next,next, last you can connected with the internet.

Mobile to PC internet connection for Nokia cell phones..

First you activated the GPRS connection from the gprs service provider.
Download the appropriate pc suite for your mobile model from nokia website. (http://www.nokia-asia.com/get-support-and-software/download-software/nokia-pc-suite)
Install Mobile PC suite in your PC.
connect your phone to PC through data cable.
Open your PC suite in your PC. it will ask connection type, choose as cable connection or Bluetooth. Then proceed further.

If your pc or laptop has Bluetooth. then we can connect the internet through blutooth in both nokia and sony ericsson mobiles.

Note : If you are in very trouble to make an internet connection in your PC, please contact your mobile service provider. They will help to you.

Thank you very much.

FFMPEG WMV3 Encoding

noreply@blogger.com (Image Formats) — Wed, 12 May 2010 08:11:00 +0000

FFMPEG

ffmpeg is a open source project used to convert one video format to other video. it supports many formats
but not all formats. the input and output formats supported by the ffmpeg is available at

http://en.wikipedia.org/wiki/FFmpeg

The compleate document about the ffmpeg is available at

http://ffmpeg.org/ffmpeg-doc.html
The recent version of ffmpeg is revision 19159. The source code is available at http://sourceforge.net/projects/mplayer-win32/files/

FFMPEG WMV3 Encoding Support

ffmpeg accepts WMV3 or wmv9 encoding files as input. as per the ffmpeg documentation ffmpeg has wmv3/wmv9 docoder but it does not have wmv3/wmv9 encoder.

so it cann't convert video to wmv3 format. but it accepts wmv3 as input and convert this into any other formats supported by ffmpeg.
Denis Fortin provide a wmv3 encoder patch for ffmpeg. but it was writtern two years back. i.e the version it is writtern for revision 9426. which is available in

http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2007-June/031695.html.

The patch file available at http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20070625/bbadb401/attachment.bin

The above patch does support for the current version available in the svn. I tried to apply pacth manualy but i am not able to find few lines of code in

mpegvideo.c , allcodecs.h etc..

As my form search in web mostly of them said that Microsoft did not give wmv3/wmv9 specification to any others. So FFMPEG supports wmv3/wmv9 decoding but not encode.

Image Dimensions:

noreply@blogger.com (Image Formats) — Sun, 07 Mar 2010 16:15:00 +0000

Image Dimensions:
The dimension image is defined as the width and height of that image. I.e. number of horizontal pixels (width) and the number of vertical pixels (height).
Example:

If an image has the dimension 1200x1600 means its width is 1200 pixels and the height is 1600 pixels. The dimension 80x60 and 200x150 are given below as the sample images.

80x60

200x150

Higher the image dimensions higher the image size. The image dimension is available at Right Click Image -> Properties ->Advanced -> summery.

Image Resolution: Dots per Inch (DPI)
It is defined as the number of pixels per inch. Pixels are also called as dots. Dots per inch represent how many dots or pixels available in an inch. It varies image to image and hardware to hardware which displays the image.
DPI for CRT Monitors and LCD Displays:
The commercial CRT monitors and LCD displays have 96 Dots per inch. To get the DPI values for normal CRT monitors Right Click in Desktop -> Properties -> Settings tab-> Advanced. The following image shows an CRT monitor DPI as 96 as normal size.

DPI for Printers :
The printers DPI varies from 200 to 300 depends on the printers. Normally the DPI value for printers would be 300. If we need the output image size is 3x4 inch then the image dimension would be 900x1200 for 300 DPI printer.

Image Bit Depth or Color Depth of an Image.

noreply@blogger.com (Image Formats) — Mon, 01 Mar 2010 15:49:00 +0000

Image Bit Depth or Color Depth of an Image.

The number of bits required to store each pixel’s color information. It depends on the image formats and the numbers of colors the images have. It ultimately shows the number of unique colors available in the image. Higher the bit depths have the high image quality i.e. higher the bit depth or color depth the number unique color is high.

For example.

If the Color depth of an image is 8 means it has 256 unique colors.

Color depth = 8;

Number of unique colors = 2^8 = 256

Depends on the number of colors bit depth can be classified as the following

1 bit images
2 bit images
3 bit images
4 bit images
5 bit images
6 bit images
7 bit images
8 bit images
24 bit images
32 images
48 images

RLE Encoding

noreply@blogger.com (Image Formats) — Thu, 25 Feb 2010 15:22:00 +0000

RLE – Run Length Encoding:

It is a famous lossless compression algorithm widely used in many data compression applications and used with many image compression algorithms. In Run Length Encoding method the consecutive same data is compressed. This technique used in few type of BMP image formats particularly 8 bit and 16 bit BMP images, JPEG images and almost all compression application software like winzip, winrar etc..

RLE – Run Length Encoding Example.

Input data : qqqqqqqqqqwwwrrrrqqqqqqqiiioooopppppp
RLE compressed Data : 10q3w4r7q3i4o6p

Let’s consider the above sample data, in RLE compression the count and the data value is represented. i.e q is repeated at 10 times instead of writing ten q it can be written as 10q. likewise all other data’s are written.

Compression ratio = (37 (total number of chars in input data) - 15 (required no of chars to represent the data) ) / 37 * 100
= 59.5 %

Compression ratio for above case is 59.5 %;

Input data : qwertyqwerty
RLE compressed Data : 1q1w1e1r1t1y1q1w1e1r1t1y

In the above sample the compression ratio is -100%. I.e. negative compression. From the above two example RLE compression is good only when the data is repeated one. Otherwise it would give negative compression.

Advantages :

1. During implementation just one pass is required to compress the input data.
2. Easy understanding.
3. Less memory requirement.
4. High compression ratio on repeated data input.

Disadvantages:

1. If the data is not repeated one then the compression ratio would be negative.

ARITHMETIC CODING

noreply@blogger.com (Image Formats) — Tue, 23 Feb 2010 16:18:00 +0000

ARITHMETIC CODING:

In arithmetic coding, Input data is represented by an interval of real numbers between 0 and 1. As the input data is large, the interval required to represent is smaller, i.e. the number of bits required to specify the interval increases. Successive symbols of the input data reduce the size of the interval according with the symbol probabilities generated by the arithmetic encoding. The repeated symbols reduce the range by less than the unlikely symbols and hence add fewer bits to the input data. The range of input data is the entire interval zero to one (0, l), which denotes the half-open interval 0.5 <> 1

ARITHMETIC CODING Example:

The Fixed model (alphabet is (a, e, i, o, u,!)) is used with the following probabilities shown in the Table.

Let’s take the input data become eaii!. Initially, both encoder and decoder know that the range is (0, 1).

From first symbol, e, the encoder narrows it to [0.2, 04],
The second symbol, a, will narrow this new range to the first one-fifth of it. Like the following

Representation of the Arithmetic Coding Process:

Suppose the input data is like a, aa, aaa, aaaa, the encoded number will be 0.0. To solve this ambiguity, In data model each data ends with a special EOF symbol known to both encoder and decoder. In the above table ! would be the EOF.

The Entropy of eaii! Is
-log0.3 – log0.2 – log0.1 – log0.1 – log0.1
= - log0.00006 ≈ 4.22

Arithmetic Encoding Algorithm:

/* Call Encode_Data repeatedly for each symbol in the input data. */
/* Ensure that a distinguished "terminator" symbol is encoded last, then */
/* transmit any value in the range [low, high]. */

Encode_Data(symbol, cum-freq)
range = high - low
high = low + range*cum-freq [symbol-1]
low = low + range*cum-freq [symbol]

/* ARITHMETIC DECODING ALGORITHM. */
/* "Value" is the number that has been received. */
/* Continue calling Decode_Data until the terminator symbol is returned. */

Decode_Data(cum-freq)
find symbol such that
cum-freq[symbol] <= (value-low)/(high-low) <>

range = high - low

high = low + range*cum-freq[symbol-1]

low = low + range*cum-freq[symbol]

return symbol