I’ve been reading on a Kobo Libra Colour for more than a year. It has wonderfully clicky buttons, a nicely textured back, a well thought-out “origami” cover, outstanding battery life, a more than decent reading environment, and a well-stocked bookshop. I like it! You shouldn’t buy it. In fact, you shouldn’t buy any colour e-reader.
You see, the E Ink Corporation has pretty much a monopoly on “electronic paper”. That means that every e-reader on the market, be it from Amazon or an unknown Chinese upstart, shares the same underlying technology. E Ink has developed five kinds of colour screens for various applications, but only two are widely used in e-readers: Kaleido and Gallery.
Kaleido builds on monochrome electrophoretic displays, which are made of microscopic “ink” capsules filled with positively charged white pigments and negatively charged black pigments. A TFT backplane placed behind the capsules controls the display by applying current to “push” and “pull” the pigments.
A positive current pulls the black pigment back and pushes the white pigment to the surface; a negative current pulls the white pigment back and pushes the black pigment to the surface. You can get shades of grey by alternating current to mix the pigments or, better yet, by using multiple electrodes to repel specific amounts of white and black on different parts of the capsule. The more capsules and electrodes, the more contrast and resolution.
Kaleido produces colour by adding an RGB filter array on top of this basic structure. Red is white filtered through the red part of the array, dark blue is dark grey filtered through the blue part of the array, and cyan is white filtered through a bit of blue and a bit of green. While this clever hack allows for 4,096 colours, it effectively reduces the resolution down to a third1.
Gallery fixes that issue by using cyan, magenta and yellow pigments in combination with white reflective particles. It behaves a lot more like ink on paper and can produce millions of colours, but is less adept at displaying crisp black text. To make matters worse, precisely controlling each pigment to produce a specific hue is incredibly complicated, which makes the display far slower.
ReMarkable is the only company that has managed to make Gallery work in a consumer product. To make it appear faster than it really is, though, they use a two-step display process. Everything appears first in the bluish black that plagues all Gallery displays, before being slowly rendered in colour. It’s as impressive as it is infuriating.
That’s why pretty much everyone else still uses one flavour of Kaleido or the other. Amazon uses a lot of tricks to make their implementation better, but in the end, the main problem isn’t display technology – it’s the whole concept of a colour e-reader. If you mostly read fiction, and we know it’s the main use of an e-reader, colour is next to useless.
Devices in the 6 to 8″ range are perfect to read mangas… but they’re mainly black-and-white. Comics are more colourful, but you’ll want a 10 to 12″ device for those. The new Kindle Scribe Colorsoft might be a great device with its 11″ enhanced Kaleido display, but at $629.99, it’s squarely in iPad territory. And an iPad won’t suffer from poor colour reproduction, subpar resolution and overall sluggishness.
As long as colour electronic paper is as grainy as Kaleido and as slow as Gallery, you should stick with black-and-white E Ink displays (or go with colour LCD/OLED). If and when colour e-paper improves enough to be worth it, you’ll still have to think long and hard about how and why you’ll use your device, and choose its size and shape accordingly. In the meantime, i’ll return begrudgingly keep my Kobo Libra Colour, only because it’s the most sensible thing to do.
- Only a half in the most recent versions of this technology, thanks to some insanely clever engineering. ↩︎