Onyx is working on a color ereader

[Nate the great]

Originally Posted by Dr. Drib

Very good, then.

I won't consider it any further.

Thank you.

me neither - the screen resolution is only 100 ppi

[pdurrant]

If the underlying greyscale screen is 300ppi and the colour filter is working on a 2x2 pixel, then the colour display should be 150ppi.

A 100ppi colour resolution would imply an underlying greyscale screen of 200ppi.

[Nate the great]

Originally Posted by pdurrant

If the underlying greyscale screen is 300ppi and the colour filter is working on a 2x2 pixel, then the colour display should be 150ppi.

A 100ppi colour resolution would imply an underlying greyscale screen of 200ppi.

I wish E-ink would give us more info!

[fjtorres]

Originally Posted by pdurrant

If the underlying greyscale screen is 300ppi and the colour filter is working on a 2x2 pixel, then the colour display should be 150ppi.

A 100ppi colour resolution would imply an underlying greyscale screen of 200ppi.

It's supposed to be a two layer system. So the color layer can be (and likely is) different resolution from the Carta film below.

[pdurrant]

Originally Posted by fjtorres

It's supposed to be a two layer system. So the color layer can be (and likely is) different resolution from the Carta film below.

I don't understand what you're suggesting. The colour filter will be a non-active fixed layer. It must align to the underlying active E-Ink screen, as far as I can see.

[Quoth]

And ALL colour screens need x3 to x5 as many pixels (coloured) to do monochrome or colour.
LCDs typically have to have x3 or x4 as many actual LCD pixels.
The colour on LCD and eink is ALWAYS a translucent dyed layer carefully aligned to the monochrome higher resolution layer underneath. A stripe filter only needs horizontal alignment (better than 1/10th pixel). Pentile or similar displays need perfect alignment in horizontal and vertical axis. Though the original Pentile cell used 5 pixels, some use a 2 x 2 arrangement (so 300 dpi needs a 600 dpi mono display underneath). Conventional systems use R G B horizontally, so 300 dpi would need a 900 x 300 dpi mono display under the filter.

The colour layer on LCD and eInk isn't active. Some AMOLED/OLED also need colour filters.
The only displays that NEVER have a colour filter are CRTs, large real LED panels, Plasma, VFD (which are only ever small and low resolution). lasers and DLP.

[Quoth]

Originally Posted by pdurrant

If the underlying greyscale screen is 300ppi and the colour filter is working on a 2x2 pixel, then the colour display should be 150ppi.
A 100ppi colour resolution would imply an underlying greyscale screen of 200ppi.

Or it's a stripe filter R G B, so you have 100dpi across the stripes and 300 dpi along the stripes.
A 2 x 2 cell using 300dpi eink would be 150 dpi.
Was there ever a 200 dpi eink? I agree, the
R G
G B
2 x 2 layout at 100 dpi would imply 200 dpi.

I'd not like to see less than 150dpi and ideally no less than 200 dpi as the limited 14 greys, black and white with a colour filter allows very limited antialiasing.
Has there been ANY ereader less than 150 dpi since 2008?

A 200 dpi colour (a minimum IMO) as
R G
G B
would need 400 dpi.

Also held at normal reading distance, rather than further distance of a PC screen, 100 dpi colour may have obvious fringing artefacts with graphic content. Real world photos are the most forgiving. Decent serif fonts at a size you'd use on a PW3 or graphic content would be poorer on a 100 dpi colour than 100 dpi mono.
I remember 80 column text on a PAL resolution monitor. VGA was bad on cheap screens using TV CRTs.

R G R G R G
G B G B G B
R G R G R G
G B G B G B
R G R G R G
G B G B G B

Certain lines will create very strange artefacts if the visual resolution is too low.
Conventional 3 x 1 underlying
R G B R G B
R G B R G B
R G B R G B
R G B R G B
R G B R G B

[kyôdai]

This is confusing... Are we sure, the information from GoodEReader is correct?

It kind of does not make a lot of sense, that Onyx would release a reader with an older CFA based color display technology, while Pocketbook and other chinese brands are using the newer, improved ACeP displays.

By the way, E-Ink has a nice overview of the different display technologies on their website:

-> https://www.eink.com/color-technology.html
-> https://www.eink.com/electronic-ink.html

[jgneff]

Here's my guess: it's using a pure black-and-white 3 × 3 pixel grid at 100 pixels per inch on a 300-pixel-per-inch display, along with a 3-way color filter on top. That would be 2^9 + 2^3 = 2^12 = 4096 colors. The pure black-and-white pixels let the device use its A2 animation mode, which explains why the refresh rate is fast enough even for color animation.

[fjtorres]

Originally Posted by pdurrant

I don't understand what you're suggesting. The colour filter will be a non-active fixed layer. It must align to the underlying active E-Ink screen, as far as I can see.

That is one way to do it but only if it relies on the Carta layer for its blacks.
But that isn't necessary. The color image might be totally independent.

The Carta layer might leave any image areas blank and tbe color layer might leave any text blocks blank.

Think of pasting a photo on a typewritten page: the text page leaves a blank spot to overlay the photo. Which can be any resolution.

[Quoth]

Originally Posted by fjtorres

That is one way to do it but only if it relies on the Carta layer for its blacks.
But that isn't necessary. The color image might be totally independent.

What you suggest hasn't been invented.

But no-one has invented such a colour device that can be totally transparent other than an LCD. An LCD actually needs a mirror and direct sunlight or a backlight and diffuser. It's got no native colour*. It has polarisers which attenuate light. It requires power to maintain the image. Greys are partial rotations of polarisation, black is 90 degrees to the polarisation of clear. Colour is a dyed filter layer aligned to the monochrome pixels. For well saturated colours the R, G and B filters need to block more of the colours not the desired R, G or B. So light losses can be well over 50%.
The LCD part is actually superfluous if you have eink, as that will provide the White (instead of clear), black and greys, just like the LCD, except there are only 14 grey levels rather than over 200 and no power is needed once the display is updated. LCD uses about the same power to maintain an image as change it.

An active three layer cell in which each dot can be clear, cyan, magenta and yellow (actually only blocking narrow red, green or blue) would let x3 to x5 more light pass than an RGB filter. RGB has to be side by side to add. CYM needs to be layers to subtract.
Both need the eink white, black and greys for colour or monochrome.
Using an RGB filter:
White = pixels white under R, G and B
Red = Pixels white under R, black under G & B
Orange = Pixels white under R and mid grey under G, black under B.
Yellow = pixels white under R and G
etc...
Pastel shades by changing black to grey and lightning greys.
Tertiary colours can't be as vivid/saturated as the eye can see, or in nature with ANY display device.
All display devices can't do fully saturated R, G and B as brightly as fully saturated Cyan, Yellow and Magenta.

[*It's possible to have an LCD where the black is sort of violet. Other colours are a using external filters. Sadly actual native C, Y and M LCDs don't exist and even if they did there would be parallax issues due to cell thickness]

[Quoth]

Originally Posted by jgneff

Here's my guess: it's using a pure black-and-white 3 × 3 pixel grid at 100 pixels per inch on a 300-pixel-per-inch display, along with a 3-way color filter on top. That would be 2^9 + 2^3 = 2^12 = 4096 colors. The pure black-and-white pixels let the device use its A2 animation mode, which explains why the refresh rate is fast enough even for color animation.

3 x 3 is a waste. You only need 3 x 1 or 2 x2 for colour. How the pixels are arranged makes no difference to the 4096.
Pure black and white pixels allows White, Black, 3 primary and 3 secondary colours on 3 x 1. Maybe three more on 2 x 2 as you can have 1 x R or 1 x B and 2 x G, or 1 x G (a greenish Cyan, a greenish Yellow and half brightness green). I agree that the 3 x 3 cell would increase the range of colours with pure black/white, but it would still be harsh and still very few shades.

[fjtorres]

Originally Posted by Quoth

What you suggest hasn't been invented.

But no-one has invented such a colour device that can be totally transparent other than an LCD. An LCD actually needs a mirror and direct sunlight or a backlight and diffuser. It's got no native colour*. It has polarisers which attenuate light. It requires power to maintain the image. Greys are partial rotations of polarisation, black is 90 degrees to the polarisation of clear. Colour is a dyed filter layer aligned to the monochrome pixels. For well saturated colours the R, G and B filters need to block more of the colours not the desired R, G or B. So light losses can be well over 50%.
The LCD part is actually superfluous if you have eink, as that will provide the White (instead of clear), black and greys, just like the LCD, except there are only 14 grey levels rather than over 200 and no power is needed once the display is updated. LCD uses about the same power to maintain an image as change it.

An active three layer cell in which each dot can be clear, cyan, magenta and yellow (actually only blocking narrow red, green or blue) would let x3 to x5 more light pass than an RGB filter. RGB has to be side by side to add. CYM needs to be layers to subtract.
Both need the eink white, black and greys for colour or monochrome.
Using an RGB filter:
White = pixels white under R, G and B
Red = Pixels white under R, black under G & B
Orange = Pixels white under R and mid grey under G, black under B.
Yellow = pixels white under R and G
etc...
Pastel shades by changing black to grey and lightning greys.
Tertiary colours can't be as vivid/saturated as the eye can see, or in nature with ANY display device.
All display devices can't do fully saturated R, G and B as brightly as fully saturated Cyan, Yellow and Magenta.

[*It's possible to have an LCD where the black is sort of violet. Other colours are a using external filters. Sadly actual native C, Y and M LCDs don't exist and even if they did there would be parallax issues due to cell thickness]

All true.
But what we're discussing is a color *eink* device, not LCD.

All vendors announcing use of these panels describe them as two-layer, with the top, color, layer used as a color filter. Which *are* transparent or at least translucent.

They also described them as having different resolutions for color and for b&w.
So either two layer eink is real or all the venors are lying...

[pdurrant]

Originally Posted by kyôdai

It kind of does not make a lot of sense, that Onyx would release a reader with an older CFA based color display technology, while Pocketbook and other chinese brands are using the newer, improved ACeP displays.

All colour ereaders and mobile phones recently announced or suspected will be using the same display technology from E-Ink, and that's not ACeP, which is so slow it's only useful for signage.

[Quoth]

Originally Posted by fjtorres

All true.
But what we're discussing is a color *eink* device, not LCD.

All vendors announcing use of these panels describe them as two-layer, with the top, color, layer used as a color filter. Which *are* transparent or at least translucent.

They also described them as having different resolutions for color and for b&w.
So either two layer eink is real or all the venors are lying...

All eink is opaque, no matter if a cell is "on" or "off".

The top layer is just a filter. The eink cells are "milky" white liquid with black balls. The cell / pixel is black when the balls are stuck to the front. It's "white" when they are stuck to the back.
So:
1) No transparency as otherwise you'd always see the black balls.
2) The only ways to have colour are
a) A coloured filter. Obviously the underlying eink is 3x resolution in one direction or x2 resolution in both directions.
b) Cells with coloured liquid instead of white. Contrast would be terrible and the resolution in 1/3rd in one direction or 1/2 resolution in both directions compared to a same geometry mono (white only).
c) Coloured balls in the milky white liquid. This has no dark shades unless there are also interspersed normal white & black shades.

The only way to have genuine higher mono resolution (for viewing rather than driving the filter) is an active transparent display of lower resolution that mysteriously works without a colour filter.

ANY colour filter layer on top of any monochrome display reduces the effective visual resolution to that of all the colour elements needed to produce white, so either 1/3rd on one axis, or 1/2 on both axis depending on how the colour is done.

If someone had invented a new display technology, we'd have heard about it ages ago. Some prove to be too expensive or too poor. Mirasol sounded good. Royalties, yield and poor colour compared to hype killed it. One eReader with two brandings for a Chinese and Korean booksellers.

There have been coloured eink for ages using the RGB filters. They need good lighting. I've seen red/black ones but it's not clear how those work. They are sold in small sizes for label applications. Probably labels are Advanced Color ePaper (ACeP) or "E Ink Spectra". I'd be surprised if that can be used to make an ereader.
https://www.eink.com/color-technology.html

Any colour ereader would use "E Ink Triton" (out for ages) or "Print Color ePaper- E Ink Kaleido", both of which are indeed the regular eink with a colour filter, just like LCD.
Poor saturation or else the panel needs too much front lighting. The Kaleido sounds like a printed plastic rather than glass filter but otherwise the same idea as Triton.
Tri= 3, so likely a 3 x 1 colour stripe, thus 300 dpi mono is a 100dpi x 300 dpi for mono or colour.


The "E ink Prism" isn't for displays.