High color

High color graphics is a method of storing image information in a computer's memory such that each pixel is represented by two bytes.

Because of this, the colour RGB (40, 40, 40) will have a slight purplish (magenta) tinge when displayed in 16 bits.

Other 24-bit colours would incur a green tinge when subsampled: for instance, the 24-bit RGB representation of 14.1% grey, i.e. (36, 36, 36), would be encoded as 4/31 (12.9%) on the red and blue channels, but 9/63 (14.3%) on the green channel, because 36 is represented as 00100100 in binary.

For a demonstration, look closely at the following picture (note: this will work only on monitors displaying true color, i.e., 24 or 32 bits) where dark shades of red, green and blue are shown using 128 levels of intensities for each component (7 bits).

More rarely, some systems support having the extra bit of colour depth on the red or blue channel, usually in applications where that colour is more prevalent (photographing of skin tones or skies, for example).