Web Design in a Nutshell, 3rd Edition

Truecolor (24- or 32-bit)

Truecolor uses 24 bits of information per pixel, with 8 bits devoted to each color channel (red, green, and blue). Now we’re going to do a little math. Eight bits of data can describe 256 colors (2⁸ = 256), so that’s 256 shades of red, 256 shades of green, and 256 shades of blue. The total possible number of combined colors is calculated by multiplying 256 × 256 × 256 for a total of 16,777,216 (usually referred to as “millions of colors”).

Specific colors from the Truecolor space are identified by their numerical RGB values. Each value is an integer from 0 to 255. For instance, the RGB values for a particular dark orange color are R:198, G:83, B:52.

32-bit monitors also display Truecolor (16.7 million colors) but they include 8 bits of empty space that may be used to represent an alpha channel. 32-bit monitors have become popular because many modern computer systems work in units of 32, allowing for better optimization in graphics display.

Professional quality image editing programs, such as Photoshop, use 48-bit color (that’s 16 bits, or 65,536 tones per channel) to track colors in images internally. Although the extra colors do not display on the monitor, the finer level of mathematical granularity is useful for Photoshop to handle subtle and repetitive image adjustments without rounding errors.

Tip

As of August 2005, approximately 80% of users viewed the Web with 24- or 32-bit monitors (statistics from http://TheCounter.com).