E-ink screens are currently only grayscale. The technology doesn’t exist yet to bring good color electrophoretic screens to consumer devices.
Nearly every display, printing, and image capturing technology has started out as monochrome or grayscale, then eventually gained color abilities in later generations. Many reporters and pundits therefore conclude that e-ink will soon be available in color.
But what if it’s not?
What if, like laser printers, mainstream e-ink will be grayscale for a very long time because it’s just much better in practice?
Electrophoretic screens currently suffer from three major shortcomings:
- Slow refresh rate.
- Low resolution.
- Low contrast ratio.
Adding color, by any currently known method, would significantly worsen all three.
The basics of the technology need to dramatically improve to make color electrophoretic screens approach the same refresh rate, resolution, and contrast ratio that we have with the grayscale screens today.
But what if they took those improvements and applied them to grayscale instead?
If they found a way to cram a bunch of subpixels into the same space as one pixel today, increased the contrast between light and dark, and increased the refresh rate, wouldn’t you rather have a much sharper, bolder, faster grayscale screen instead of a barely-acceptable color model?1
That probably depends on whether you own an ebook reader.
If you don’t, or if you’re a tech journalist, you probably assume that the progression to color is inevitable and will be unequivocally better. (You may also name the CrunchPad the best gadget of 2009 before ever seeing one, or criticize current products for not comparing well to “the upcoming Apple tablet”.)
But down here, below the clouds, in the world of ebook-reader owners, I can guarantee you that the times I want color are far outnumbered by the times that I’d benefit from sharper, bolder, faster grayscale.
The numbers break down something like this:
- Times I’ve wanted color: I don’t know. Maybe one or two? I can’t remember any. But it has probably happened once.
- Times I’d benefit from grayscale improvements: Every time I use it.
This isn’t to say that there’s no reason to make any devices with color e-ink screens, but I don’t think there’s much reason to make mainstream ebook readers with them.
The question of how to display black on a reflective color screen could screw color e-ink readers. If black is simply the full density of red, green, and blue (or cyan, magenta, and yellow) in close proximity, it would look awful. If there’s a separate black subpixel, what do the color subpixels display when the pixel is showing pure black?
Early inkjet printers blended C/M/Y to create black instead of having a separate black ink cartridge. Black text printed this way was blurry, muddy, and awful. But at least the liquid ink would blend together on the page. Color electrophoretics wouldn’t have that luxury. ↩︎