About Color LCD Displays

In colour LCDs each individual pixel is divided into three cells, or subpixels, which are coloured red, green, and blue, respectively, by additional filters (pigment filters, dye filters and metal oxide filters). Each subpixel can be controlled independently to yield thousands or millions of possible colours for each pixel. CRT monitors employ a similar ‘subpixel’ structures via phosphors, although the electron beam employed in CRTs do not hit exact subpixels.

Color Interface Pixel Format

Most important thing in interfacing color LCD is to know how color is defined to a given pixel. The NXP PCF 8833 Color LCD controller for example, has three modes of color interface pixel format.

12 bit per pixel pixel format

RRRRGGGG 4 bits red and 4 bits green 1st pixel
BBBBRRRR 4 bits blue 1st pixel and 4 bits red 2nd pixel
GGGGBBBB 4 bits green and 4 bits blue 2nd pixel

8 bit per pixel pixel format

RRRGGGBB 3 bits red, 3 bits green and 2 bits blue

16 bit per pixel pixel format

RRRRRGGG 5 bits red and 3 bits green 1st pixel
GGGBBBBB 3 bits red and 5 bits blue 1st pixel