[mdp2021]

Do not miss an important detail: it is Kaleido.

It means, it uses an overlaid colour filter matrix (RGBW, if I remember correctly). This allows for the comparatively high refresh rates of B/W EPD, but it is B/W EPD with a semi-transparent multi-tinted layer on top, which obviously impacts the brightness.

(The alternative would be multi-pigmented EPD cells - "Advanced Color E-Paper"... Which suffers from dramatically low refresh rate.)

[Qwertious]

Here's a diagram to help explain your point: https://etulipa.com/wp-content/uploads/2020/04/lightreflexti...

The one on the right is Kaleido (CFA tech). See how you lose 2/3 of the light? Monochrome (and ACEP etc) doesn't have that problem. Just CFA.

(This diagram is from Etulipa, and is meant to explain a benefit of their billboard-sized passive displays compared to CFA tech; Etulipa tech is really cool but it's not suitable for e-readers or desktop monitors, as they found out the hard way back in ~2010.)

(CFA = Color Filter Array)

[ddingus]

Dramatically low basically equals the single color refresh rate multiplied by the number of base colors used to form color images.

[dmitrygr]

No. Much worse. Think 30 seconds for a 7-color display. (B&w can do under one second)

[Qwertious]

This is outdated and only true for older ACeP displays. The Gallery 3 screen can refresh fast enough (~1.5sec) to be usable in an e-note with color:

https://youtu.be/V3jmmo23J5w?t=1202

And since it's true multi-color, it can refresh even faster by simply disabling the colors and refreshing in B&W (very slightly slower than monochrome screens though).

[mdp2021]

You seem to be suggesting "a collection of pigmented subcells similar to the traditional B/W cell".

ACeP works differently: the pigments are in a single cell, and it is a matter of different densities, size, speed, electrical sensitivity per material (per pigment) that determines the procedure ("waveform") to obtain the wanted colour in a pixel.

So, it does not seem linear at all.

[ddingus]

That was based on my tests with color displays from Waveshare, and as we have seen in the comments here, advances have been made.

I still see multiple refresh cycles being needed for colors. The metrics are shorter, smaller on the very latest displays, and in my view fall short of motion capable in color.

We do have, and have had, motion capable monochrome for a while now, given users accept a few trade-offs.

[Qwertious]

This is no longer true - Gallery 3 screens are ACEP that can refresh in a second and a half. For instance the Bigme Galy is an e-reader based on the Gallery 3, and [as you can see](https://youtu.be/V3jmmo23J5w?t=1202) is perfectly functional for interactive use.

It's still slightly higher than monochrome, but only by milliseconds. IMO, fast-ACeP is the future and will eventually kill CFA/Kaleido.

[ddingus]

Seems to me it remains largely true, just with much smaller numbers.

That screen is nice! Real progress being made there.

[Scene_Cast2]

Oh, interesting detail. I was looking towards the rumored Fujitsu Quaderno A4 Gen 3, which is supposed to have a Kaleido 3 color panel.