Do e-ink / e-paper screens work in the RGB, CMYK, or some other colour space?

Question

Do e-ink / e-paper screens work in the RGB, CMYK, or some other colour space? Will we need to support native CMYK displays in the near future? I'm designing a data structure with colour information and want to know whether the colour part ought to support expansion beyond four colour components (for, say, CMYKA).

Answer 1

The current technology of electronic paper is constantly moving. Most current implementations, like Amazon's Kindle, only support 2 bit (4 levels) or 4 bit (16 levels, Kindle 2) gray scales. It depends on the software how color information is translated.

More modern implementations support color. The used colors are Cyan, Magenta and Yellow. The method works opposite to CRT displays: the colors are subtractive as opposed to additive (CRT). That means: remove all colors and you get white.

Currently every new system may introduce a new color scheme. If you consider building a data structure, make sure that enough information is in to easily convert to other structures. Don't rely on the hardware. Create one structure, and create software to go from your structure (device independent) to a device dependent structure.