15-bit High Color
In 15 bit high color, one of the bits of the two bytes is ignored or set aside for an alpha channel, and the remaining 15 bits are split between the red, green, and blue components of the final color, like this:
Sample layout of a 15 bit color data in a 16 bit pixel (in RGBAX notation)
Sample layout of a 15 bit color data and Alpha channel in a 16 bit pixel (in RGBAX notation)
Each of the RGB components has 5 bits associated, giving 25 = 32 intensities of each component. This allows 32,768 possible colors for each pixel.
The popular Cirrus Logic graphics chips of the early 1990s made use of the spare high-order bit for their so-called "mixed" video modes: with bit 15 clear, bits 0 through 14 would be treated as an RGB value as described above, while with bit 15 set, bit 0 through 7 would be interpreted as an 8-bit index into a 256-color palette (with bits 8 through 14 remaining unused.) This would have enabled display of (comparatively) high-quality color images side by side with palette-animated screen elements, but in practice, this feature was hardly used by any software.
Read more about this topic: High Color
Famous quotes containing the words high and/or color:
“If there be no nobility of descent in a nation, all the more indispensable is it that there should be nobility of ascent—a character in them that bear rule, so fine and high and pure, that as men come within the circle of its influence, they involuntarily pay homage to that which is the one pre-eminent distinction, the Royalty of Virtue.”
—Henry Codman Potter (1835–1908)
“African rights and liberty is a subject that ought to fire the breast of every free man of color in these United States, and excite in his bosom a lively, deep, decided and heart-felt interest.”
—Maria Stewart (1803–1879)