Last updated: November 2023
During 2023, quite a few colour e-ink tablets were released, with Boox and Bigme being the primary players.
Consequently, when reviewing these devices, I often find myself writing the same stuff about colour e-ink, and it has become quite repetitive.
So the objective of this article is to describe the advantages/disadvantages of colour e-ink in a single place so that for future articles, I can simply link back to this article instead of repeating myself.
The most popular colour e-ink technology that is being used on e-ink tablets is called Kaleido.
I won’t go into the technical details of Kaleido colour e-ink technology (E-Ink Corp themselves give a decent overview here) other than to say it involves placing a thin film over a monochrome e-ink screen that filters the black-and-white pixels to display color pixels.
It is not so much a colour display technology in and of itself, but more of a way to convert a monochrome display into colour.
The latest (and best) incarnation of Kaleido is Kaleido 3.
Before this came Kaleido, followed by Kaleido 2, and then Kaleido Plus, with incremental improvements with each iteration.
E-Ink tablets on the market today use either Kaleido 3 or Kaleido Plus.
The main advantage of the Kaleido over monochrome e-ink is (obviously) that it displays colours.
And it does do a pretty decent job in this regard.
However, colours are not as bright or as vibrant as backlit screen technologies, such as LCD or OLED displays. In comparison colours look rather pale and washed out and there are some variations in the hue that is displayed, as can be seen in the comparison below:
Resolution and Pixel Density
All the newest Kaleido 3 e-ink tablets are used in conjunction with top-of-the-range Carta (monochrome) displays, which means a high resolution (1860 x 2480) and pixel density (300dpi) when viewing black-and-white.
However, when viewing colour on Kaleido 3, the resolution and density drops by 50% (930 x 1240 and 150dpi). For older Kaleido Plus tablets, resolution and screen density falls by two-thirds.
This, in part, explains why colours appear to be quite muted on Kaleido screens.
Something about the colour filter makes Kaleido screens significantly darker than their monochrome counterparts – I could make an educated guess as to why this is but I won’t because I am far too unqualified to do so!
The fact of the matter is that with frontlighting turned off, what should be a whitish background is actually quite dull and shaded, resulting in poorer contrast.
Having said that, this is only really noticeable in environments with low natural light. For me, it is very noticeable when sat at my desk, where I am around 8 metres away from the nearest window and the artificial lighting is not all that bright. However, if I take a Kaleido tablet outside, the screen does not look too dark at all.
In addition, all Kaleido screens that I’ve seen also have adjustable frontlighting, which means that the brightness and temperature of the screen can be configured to suitable level dependent of the ambient light of the environment. The drawback to this is that you have to spend a little time adjusting the settings and it will drain the battery slightly quicker.
Subjectively (as I haven’t carried out any tests in this regard), Kaleido screens seem to experience more ghosting than monochrome screens. “Ghosting” is the term used when you can see faint imprints of previous content on the screen.
Now, the ghosting is not frequent enough to result in severe frustration, and it can easily be cleared by a swipe or tap of a button, but I do seem to experience this more with colour e-ink than monochrome.
However, it should be noted that when I am using a colour e-ink tablet, I am often viewing image-based content, which will display more black/colour pixels than if I were simply viewing text. With more pixels “turned on” (for want of a better phrase), more pixels will have to be “turned off” when I change what is on the screen.
I’ve not done a very good job of explaining what I mean, but the upshot is that I could be observing more ghosting on Kaleido tablets because of the graphics-based content I typically use it for rather than it being an issue that is inherent with colour e-ink.
The colour filter is honeycomb-shaped and on older Kaleido screens, you make out a honeycomb grid pattern when the screen is viewed from particular angles.
Although this was quite noticeable with Kaleido Plus, I can’t say that I’ve observed this on any Kaleido 3 tablet.
Gallery is an alternative colour e-ink technology by E-ink corporation. It is based on their Advanced Color ePaper (ACeP) technology, which is a full-colour solution rather than using a filter to convert a monochrome screen into colour (as is the case with Kaleido). It has higher pixel density (300dpi color) than Kaleido.
It was originally used for applications such as displays and signage, however Gallery 3 was developed to be used with e-ink tablets.
Unfortunately, the only e-ink tablet that has used this screen technology is the Bigme Galy, which we felt was not yet ready for the consumer market.
DES Slurry is another “true” colour e-ink technology that has been used on a couple of crowd-funded e-ink tablets (the Topjoy Butterfly and Reinkstone R1). We didn’t back these devices and so have not seen them first-hand but other reviews were not favourable.
I feel like I’ve painted a picture of colour e-ink screens being absolutely awful, however, this really is not my intention at all – my Boox Note Air3 C is actually one of my favourite e-ink tablets.
But I did want to highlight the current reality of colour e-ink so that individuals can make their own informed a choice about whether this technology is right for them.
You can perhaps think of colour e-ink as adding a splash of colour to a monochrome display and for some use cases, this will be invaluable.
For example, if you are studying textbooks that have colour diagrams, the experience is far better on colour e-ink than monochrome. Similarly, the option to use colours in your notebooks can harness more creativity in your writing and sketches.
However, for those that are typically reading and annotating black-and-white documents, the drawbacks of colour e-ink highlighted above actually means that the experience is probably better on a purely monochrome display.
And this sort of embodies the point I wanted to make – current colour e-ink technology is not always an upgrade for every single use case. All else being equal, if you have the choice between colour or monochrome, the obvious answer is to go with colour. However, all else is not equal, and you do have to make a few compromises for the luxury of colour, including pale colours, a darker screen and perhaps more frequent ghosting.
For some, having a screen that displays colour will be far more beneficial than the drawbacks. For others, having colour capabilities will not outweigh the additional quirks and eccentricities that come as part of the package.
In summary, I would recommend only going for colour e-ink if you are absolutely sure that you make full use of the colour capabilities. If colour is something that you don’t really need, but would perhaps be desirable, weigh up the pros and cons and consider a monochrome tablet instead.
And, if you do decide on a colour tablet, a Kaleido 3 screen currently provides the best quality.
About the author
Dan Dutton is passionate about E-ink writing tablets, which bring together the pleasure of writing on paper with the power of digital technology. When he bought his first tablet, he realised that there wasn't a lot of unbiased information available for people that were considering buying an E-ink tablet, and so he built eWritable.