E Ink's Kaleido 4 color e-paper doubles color gamut, adds 50% contrast boost and 18fps refreshes

E Ink has unveiled Kaleido 4, the next generation of the color e-paper technology used in most color e-readers sold today. According to The Verge, the new panels bring improved color reproduction, better contrast and faster screen updates, targeting the most common complaints about the current Kaleido 3 generation.

Kaleido 3 screens appear in e-readers and tablets from Kobo, PocketBook and Boox, while Amazon's Kindle Colorsoft relies on a customized variant tuned for better performance. Because so many devices build on the same underlying panels, improvements E Ink bakes into the base technology tend to reach a large share of the color e-reader market.

How Kaleido works, and what held it back

E Ink builds color screens in two very different ways. Its Gallery 3 displays, found in the reMarkable Paper Pro, use colored pigments that physically move around the panel to form full-color images. Kaleido takes the opposite approach: it layers a color filter over an e-paper panel containing only black and white pigments.

The filter approach has one major advantage: speed. Gallery 3's slow refresh rate can feel frustrating to use, while Kaleido panels update much faster. But the trade-offs are significant. Color images are rendered at a lower resolution than black-and-white text, the palette is limited and colors often look washed out. The color filter also leaves plain text looking darker than it would on a monochrome E Ink screen.

What Kaleido 4 improves

According to The Verge, E Ink claims Kaleido 4 doubles the "color gamut volume" of its predecessor, which should make images look noticeably more vivid. White reflectance increases by 15 percent and contrast improves by 50 percent, so plain text should appear less muddy than it often does on current color e-readers.

The limitations have not disappeared entirely. As The Verge points out, Kaleido 4 still produces just 4,096 colors, while modern LCD and OLED panels can produce millions, and color content is still displayed at a lower resolution than black-and-white text.

The bigger leap is in responsiveness. A new oxide TFT backplane, which The Verge says sounds similar to what the Kindle Colorsoft uses, pushes refresh rates up to 18fps. That is fast enough for video playback, something the color-filter approach has never managed before.

First device: Hanvon's M10C II

Neither Amazon nor Kobo has announced hardware built on Kaleido 4 yet. The first adopter is Hanvon Technology, whose upcoming M10C II tablet will ship with the new display. The Verge reports that the device will only be available in China, and that its Kaleido 4 screen features a micro-etched tempered-glass surface designed to reduce glare while making note-taking with its battery-free pen feel more like writing on paper.

Why it matters

Color e-readers have so far been a compromise: buyers gave up the crispness and contrast of monochrome E Ink in exchange for a splash of color that often looked dull. Kaleido 4 attacks both sides of that bargain, promising richer and brighter images, clearer text, and refresh rates fast enough to handle video. If those claims hold up in shipping hardware, the next generation of devices from the likes of Amazon, Kobo and Boox could become meaningfully better, and e-paper could start competing for use cases that have previously been off-limits to reflective displays.