6 replies to this topic

[hug-hes]

I need to write a C++ program to give me the RGB values for a bitmap image so that I can calculate different areas of colours in the image.

Any help would be appreciated!!:yes:

[Goz]

Assuming your bitmap stores 32-bits per component u would do it as follows.

unsigned int uRGB = ((unsigned int*)pBitmap)[x + (y * width)];

unsigned char uR  = (uRGB & 0x00ff0000) >> 16;

unsigned char uG  = (uRGB & 0x0000ff00) >> 8;

unsigned char uB  = (uRGB & 0x000000ff) >> 0;

Of course this assumes that its 32-bit and that R, G and B are in that order. If not you have to modify that basic algorithm a little bit.

Hope that helps!

[hug-hes]

can u explain what this means?

[Goz]

Ok .. "width" is the bitmap's width. "x" is the x coordinate position and "y" is the y coordinate position.

The code above looks up a 32-bit value from the bitmap at (x,y) and then breaks the value up into individual RGB components.

[hug-hes]

thanku for your help!

I am still having trouble loading my bitmap file

[Goz]

Hmmm ... if you are trying to load a .bmp directly you may find www.wotsit.org useful. It describes numerous file formats ... including the bmp format :)

[hug-hes]

I will check it out thanks