Get file information .bmp

Question

I am fairly new to .bmp I want to learn more about it. I have a .bmp file now and I wonder where I would get the headerinformation, file information etc. Baisically, I need the written code behind the image (not open the image itself, but see what is written there - the bitmap, the header etc.). I want to access the information you can read on wikipedia here

I do not know how to open the file to get these information... I though I can read it somehow in a texteditor..

Can anyone pinpoint me in the right direction?

Answer 1

You said:

Assuming I want to find in the HEX Code the size of the image. How would I get that HEX Code

So, pick any BMP file and open it in a hex editor. From the specification you link to:

All versions of BMP format files begin with the following 14-byte [file] header:

[...]

Version 4.x BMP files begin with the same 14-byte header as v2.x and v3.x BMP files. The file header is also followed by a bitmap header, which is an expanded version of the v3.x bitmap header

typedef struct _Win4xBitmapHeader
{
    DWORD Size;            /* Size of this header in bytes */
    LONG  Width;           /* Image width in pixels */
    LONG  Height;          /* Image height in pixels */
    [...]
} WIN4XBITMAPHEADER;

So the first header is 14 bytes. The 15th-18th byte define the second header's lenght. Then follow two longs, of four bytes each, giving you the width and height of the image.

So byte 19-22 give the width, byte 23-26 give you the height - for a version 3 or 4 bitmap. Version 1 and 2 use one respectively two bytes for each dimension, so be sure to inspect the bitmap version first (by analyzing the header size).