The depth of color refers to the number of colors in an image or a screen. The depth of an image is usually measured in colors contained by the image. The depth of a screen is usually measured in bpp (bits per pixel) or cpp (colors per pixel).

Here are various color depths for reference:

Bits per Pixel Colors per Pixel Comments
0 2^0 = 1 Your monitor is off.
1 2^1 = 2 "Monochrome". Sufficient for black and white line art or halftones.
2 2^2 = 4 Sufficient for most grayscale images.
3 2^3 = 8  
4 2^4 = 16  
5 2^5 = 32  
6 2^6 = 64  
7 2^7 = 128  
8 2^8 = 256 Used in VGA. Also sufficient for most grayscale images. 
16 2^16 = 65,536 "High Color"
24 2^24 = 16,777,216 "True Color". Actually stored as 32 bpp, but 8 bits are unused.

Page Modified: (Hand noted: ) (Auto noted: )