Can you get 32 level grayscale out of an E-ink display?

https://hackaday.io/project/11537-nekocal-an-e-ink-calendar/log/72153-can-you-get-32-level-grayscale-out-of-an-e-ink-display

by userbinator • 9 years ago

153 47 9 years ago

hackaday.io

userbinator5• 9 years ago

E-inks are fundamentally analog, so theoretically you could have as many shades of gray as your timing resolution allows, but basically all the commercial controllers available abstract the display as a dumb framebuffer so you can't really access their fundamental operation of "make this pixel slightly whiter or darker.

JoeAltmaier• 9 years ago

So many (all?) do this dumb thing on a page update where they write all black and all white several times then write the image. There can't be a good reason for that - they can also put up a dialog popup and erase it without all that drama! Its like they all took the demo driver and shipped it

userbinator5• 9 years ago

The full black/white is to "cleanse" --- since the material itself is stateful, pixels will drift slightly after several writes and cause ghosting/graininess if you don't eventually reset them all to a known state. It doesn't have to happen on every refresh, however.

dfox• 9 years ago

That depends on what you exactly mean by "controller". The hardware controller typicaly has capability of exposing selected pixels to essentially arbitrary voltage level for specified amount of time and the framebuffer abstraction happens on the driver level.

userbinator5• 9 years ago

The majority of dev kits and modules available abstract away that level and provide something not unlike a regular LCD where you just send it raster images; the driving waveforms etc. which are needed to do effects like this are abstracted away, and the details are kept secret.

Dylan16807• 9 years ago

Timing plus calibration plus unpredictability on the color change speed. Overdriving is a lot easier than subtle and consistent analog performance.

dawnerd• 9 years ago

Relevant: https://youtu.be/MsbiO8EAsGw

aphextron• 9 years ago

Video capable (>30hz) color e-ink displays are on the way too https://www.youtube.com/watch?v=pqn2650CJYc

gravypod• 9 years ago

I can't wait for a future where something like that makes it's way into a reMarkable.

ernesth• 9 years ago

Another video: https://www.youtube.com/watch?v=24srQXX81Oc (7 years ago)

iMark• 9 years ago

All the years e-ink displays have been available in consumer products and we're still only talking about 5 bit greyscale?

I gave up my Kindle as soon as 5 inch displays were available. I thought the market would have made more progress by now.

userbinator5• 9 years ago

I thought the market would have made more progress by now.

I believe the reason is that there are a lot of patents/IP around the core technology, and it's owned by very few companies who essentially have a monopoly on the market. This also explains the secrecy surrounding the "low-level" details. As this article shows, you can definitely get more gray levels by driving the display directly.

fapjacks• 9 years ago

Yes and it's also been somewhat notoriously difficult to actually procure the damned things.

gatmne• 9 years ago

It's a shame.

From past examples, we will likely not see any real innovation in this space until these patents expire. It's especially disheartening to me since I'll probably be too old to get in on the action by then.

I hope societies reevaluate the role of patents in the advancement of human technology. From my perspective, patents do more harm then good. They encourage rent-seeking. They're impractical to use legally unless you have enough money. They hold back technology for a couple of generations each time a new breakthrough is discovered (as has happened with capacitive touch screens, 3D printers, and is happening now with e-ink displays).

To me, patents are achieving the opposite of their intended purpose.

rb808• 9 years ago

Nice. Looks like my old HP48.

stevekemp4• 9 years ago

That's pretty neat to see! ePaper displays are now starting to become quite affordable. I recently bought a 400x300 pixel display for about €25.

Unfortunately my device has only "black & white", no shades of gray at all, but I had a lot of fun working out how to drive it from a small MCU, without running out of RAM.

https://steve.fi/Hardware/d1-epaper/

stefanpie2• 9 years ago

I've recently picked up a e ink display with a simple passive interface board (bc Im not used to working with flex cable yet) and realized that a popular way to build the frame in the mcu memory then dump it to the board. Most hobby mcus like the atemga328p have enough static memory to store whole frames of images and then push the whole image to the display, but don't have enough dynamic memory of you want to dynamicly render whole frames and then dump them. So I think that's what you are referring to when you said your trying to figure out how render the frames without running out of memory. My screen had example code that would draw frames an push small windows of image data to the screen to draw the different parts of a complete image.

The reason I bring this up is because I recently had the idea of using small SPI flash memory chips to render the whoel.inage frame dynamicly. The SPI memory chips look like a neat way to easily do this by hooking one up to a small mcu and drawing the frame using the spi memory chop then dumping the whole frame from the memory chip to the screen. I hope to oder some small DIPs soon to experiment with and I thought it also might interest you as well.

stevekemp4• 9 years ago

You're pretty right on all counts :)

emj• 9 years ago

Can you calculate it on the fly by doing a slower transfer to the display, I'm guessing it already does double buffering?

userbinator5• 9 years ago

You can get 800x600 6" displays for that price, intended as eBook reader replacement parts; a while ago someone figured out how to drive them without the official controller:

http://essentialscrap.com/eink/

That's the same model/family of panel as the one showing 32 shades of gray in this article, and the author has done some other stuff with it:

https://hackaday.io/project/11537-nekocal-an-e-ink-calendar

Unfortunately my device has only "black & white", no shades of gray at all

That's because it's a module with its own controller for producing the display driving waveforms from the 1bpp data that you feed it --- but if you disassemble the module and figure out how to drive the display itself (it's probably not unlike the link above), you could get grayscale too. In addition, you could probably stream from network to display with almost no buffering, by clocking the data directly into the display as it's received over the network (although you'd have to clear each line before drawing it; unlikely to be very difficult, in any case.) Also, refresh as fast or slow as you want.

stevekemp4• 9 years ago

Agreed on all counts!

dzhiurgis• 9 years ago

And yet, good readers, like the ones you can use as an external display are something like $600 https://www.youtube.com/watch?v=1huyi7mgbzY

ISL• 9 years ago

Awesome; can't wait for better e-ink displays.

Anyone aware of reasonably affordable greyscale E-ink displays at or larger than a piece of letter-paper?

There's an interesting thread from a year ago, but would love to know if prices have dropped/availability increased.

https://news.ycombinator.com/item?id=13771203

thisacctforreal• 9 years ago

The reMarkable e-paper tablet is 10.3"

The product video does a great job at covering the trade-offs.

https://remarkable.com/

beezle• 9 years ago

I got a reMarkable as part of the original lot of buyers. Haven't had quite as much time to use it as I'd like but can summarize:

-would like a little better contrast on the screen, though it does seem roughly on par with kindles and the like with lighting off

-epub generally works well

-full size (ie, letter) pdfs do require cropping unless your vision is superior. The on-device crop is fine for text only pdfs but recommend using an external cropper for pdfs that have charts. Going this route has made it possible to read Reviews of Moder Physics on the reMarkable without the need to squint.

-it could use a 20% speed bump. Some of this might be achieved in future software updates.

You can, of course, use it for its other intended purposes - note taking and draw/sketching.

Simulacra• 9 years ago

Is it possible to combine an e-ink display with a tablet display? For example, when your iPad is in sleep mode, it's a reader.

petecox• 9 years ago

There's a dual screen Android phone by a Russian company, Yota.

www.yotamobile.com/index-EN.html

polshaw• 9 years ago

The Yota phone has an e-ink display on the back. I got the impression OP was talking about stacked displays. I can't see why that wouldn't be possible.

alok-g2• 9 years ago

Not using E-Ink, but Pixel Qi attempted combining those:

https://en.wikipedia.org/wiki/Pixel_Qi

pasbesoin• 9 years ago

Is this "transflective" concept and technology dead now (commercially, R&D, etc.)? For a long time, I was waiting for a responsive display that I could read like a piece of paper.

chuchana• 9 years ago

There’s a patent for that: https://www.pcworld.com/article/224698/apple_develops_e_ink_...

wernsey• 9 years ago

Very cool.

I recently got a Waveshare 4.2" e-paper for my Pi, and I've been playing around with a variety of dithering algorithms to get it to display images.

The Floyd-Steinberg algorithm seems to bring out the most detail if you look at the image from a distance, but ordered dithering (with the 8x8 Bayer matrix from Wikipedia) gave me a better "retro computer" look that I was aiming for.

Can you get 32 level grayscale out of an E-ink display?

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