Sensible
Using CMY instead of RGB makes a lot of sense. There's a reason people use it for printing. Full CMYK would make even more sense, and would probably be fairly easy to add.
Here's a snap of Ricoh's colour e-paper, which, the company claims, is two-and-a-half times brighter than anyone else's colour e-paper. There's not much colour e-paper out there at the moment, you may have noticed, so Ricoh's boast is a mite hollow. Ricoh e-paper It also reckons its offering has "about four" times as wide a …
Glory be, those guys with the RGB one are superlative idiots.
When was the last time you saw an RGB printer? Colouring a surface *does not work that way*.
I hereby claim the idea of "CMYK" E-paper.
I also claim CcMmYyK (Light and dark of each secondary colour) and any combination thereof which would give different gamuts at various price points.
This is now my idea, and I release it for free because I want every e-paper manufacturer to use it, unencumbered by stupid patent trolls trying to claim the bleeding obvious.
Although I've sort of followed the development of e-ink/e-paper with some interest, I've never really looked at the underlying technology.
This article has surprised me in that existing colour e-ink/e-paper is using RGB while Ricohs new offering is CMY.
Since e-ink/e-paper relies on reflective not emitted light I'd have assumed they were all using CMY colours. Ir's the difference between additive and subtractive colour mixing.
Of course, I may be making incorrect assumptions here. No doubt a master printer will be reading and correct me if I'm wrong ;-)
Whatever the whys and wherefores of the underlying technology, it's still another step forward to the day when I can walk into the local DIY shop and buy some rolls of active wallpaper and decorate for the very last time. Next time the wife changes her mind over the colour scheme, she can push the damned button and change it.
I think the picture explains this one. Their system uses subtractive colour mixing (CMY) because there's a reflector at the back, so the reflected light is being filtered by the active layers (presumably in both directions). Other systems use additive colour mixing (RGB) because it's the active layers that are doing the reflecting - the background is dark. I can only assume that others have found it easier to reflect light rather than filter it up until now.
Actually, a rather novel but sensible approach to the E-ink problem since that's the same color system printers (of all sorts) use. The catch is that most color picture files today use additive coloring (RGB), so some conversion will be necessary for color e-books to appear correctly on a Ricoh screen. There's also the matter of refresh rate. Something tell me this is strictly an e-book material and not one that refreshes quickly enough for multimedia uses.
You can get a reasonable approximation by using Cyan = Not Red, Magenta = Not Green, Yellow = Not Blue.
The better algorithms take account of the particular bandwidth of each of the specific CMY filters in use.
You'll find the algorithm in your printer driver. Even the really good ones are trivial to process.
That's even before you realise that almost all the imagery this is intended to be used with is stored in CMYK format already, as that's what was used to make the 'real' book!
I've done some pretty good approximations for RGB->CMYK->RGB conversions in Javascript before now. As the screen itself is probably going to have an awful refresh rate anyway, you could probably get away with some cheapo embedded microcontroller that costs about 5p when bought in bulk.
While it is sensible to use CMY instead of RGB for a reflective medium, they really need to add a K layer, or black print is going to look rather muddy.
Early colour inkjet printers (Canon, I think), didn't have any black ink and produced blacks by blending CMY. The result was text that looked a sort of muddy brown, which is just what you don't want for an eBook where the clarity of the text is the biggest advantage eInk has over LCD.
I may actually be tempted to buy an e-reader if it supported color e-Paper/e-Ink, as long as it also had full support for reading PDFs, e.g. re-flow and font scaling on sub-A4 displays and a fast enough page refresh/turn that didn't kill my visual cortex after ten minutes.
Actually, bugger that for a lark, I'll take any e-Ink/e-Paper reader that actually has full PDF support, even if it is just black and white. Yes, I'm in Europe, so even the next best thing, a Sony PRS-950, is out of the question ...
Unless the reader software can reflow the PDF to comfortably fit the display area of the reader (and I've not yet seen one that can) then they are intrinsically unsuited to each other. IMO and it is just an opinion albeit based on experience I would say if PDFs are much better viewed on a <Insert favourite tablet here>
was the elimination of the very end-user orthogonality you're talking about. Back in the 90s, HTML was designed to be orthogonal to the user - that is, the user had control over the text flow, colours, layout and so on. If the page author created his page in 8 pt black Arial with images floating to the left and you wanted to view it in 72 pt pink Garamond with non-floating images, there was nothing he could do about that. Consequently it was difficult for designers who wanted fixed-format, predictable document layouts to achieve that in HTML. Adobe, seeing a market for a fixed-layout document format that removed any end-user control over presentation, invented PDF for that very reason.
So PDF is not designed to appear any way other than the author intended it to. Ironically, HTML, which is a format that would have lent itself perfectly to ebook formatting back in the 90s, is becoming, in its current designer-oriented incarnation of HTML 5 and CSS 3, more restrictive of end-user orthogonality than PDF is!
LCDs are clear or Black. So don't work in three layers of CYM. Hence they have to have additive dots side by side. Each dot has to block entirely cyan (leaving red), magenta (leaving green) and yellow (leaving blue) wasting at least 2/3rds of the backlight. Real LED displays (like fill a wall) are Red, Green and Blue LED dots. AMOLED are really yellow or UV/Violet (with phosphor to get white), Most have LCD style RGB filters.
To use CYM you need a display that each element is coloured or transparent. The mono eInk in kindle etc uses tiny balls that are black on one pair of faces and white on the other, so they have to to use RGB filter additive side by side for colour which makes them VERY dim.
They must be using a liquid dye type display, each cell is empty (clear) or filled with cyan, yellow or magenta liquid. Parallax is an issue unless the cells are very much thinner than they are wide and high. OTH each cell can be 3x bigger than the RGB additive technique. Or twice as big for additive RGB arranged
RG
GB
for 2 x2 subpixel instead of older 3 x1 RGB stripes.
I like the way that this looks like the sub pixels are all on top of each other instead of next to each other as for normal colour displays. I suspect that could make the biggest difference as to how easy on the eye colour e-ink displays are compared to "normals". I think that seeing a full single colour pixel instead of 3 different brigtness RGB sub-pixels near each other will really help.
As for CMY instead of RGB, it all depends on how their layers work. Obviously the RGB boys have layers that reflect that colour when activated, so even though the display is reflective, the different bits that are reflected add, hence RGB. Ricoh's layers obviously attenuate when activated and so are subtractive.
As far as black is concerned, it all depends on how attenuative their layers are, like my LCD TV which despite having a claimed contrast of 100000000000:1, can't do black unless I turn it off.
Just a fast word about Ricoh, who ALWAYS go against the tide, against the grain, and usually end up with something niche, and utterly cool, such as their compact but pro quality cameras. I have no stock, no affiliation, but I just LOVE a company that can find niches and work to exploit them against their bigger rivals. Ricoh has guts...they ought to relocate to Silicon Valley...