How are individual pixels represented in memory?

Created Jan 28, 2000

John Zukowski

Each pixel is stored as a 32 bit integer (int). The int packs four unsigned bytes within it, one for each of the alpha, red, green, and blue (ARGB) color planes, in that order.

Alpha (8-bits)	Red (8-bits)	Green (8-bits)	Blue (8-bits)
32 bit pixel

To get at each value, you would use a masking operation and a bit shift :

int alpha = (pixel & 0xff000000) >> 24;
int red   = (pixel & 0x00ff0000) >> 16;
int green = (pixel & 0x0000ff00) >> 8;
int blue  = (pixel & 0x000000ff) >> 0;

Keep in mind that you cannot store each value in a byte as bytes are signed.