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I built a picture frame with a greyscale e-paper that runs on battery for years

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Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#61

Post by ekianjo »

clash wrote: post #26
baybal2 wrote: post #23

I worked on a number of digital photo frames, including on ones like that. E-ink is not the most suitable thing for it in its current form. First, large size EPD cost an arm, and a leg, and custom one costs even more. Second, there are no 8 bit EPD controllers as of now a mortal can buy, which means grays look very bad. Third, there are inherent physical limitations which make increasing gray resolution of EPDs quite…

At 150 dpi the image depth is not a problem. Here is the 4-bit image of the 1929 Bentley as displayed on the frame for reference: https://www.instagram.com/p/CItoGRLh52n/ On the device you only notice if you get extremely close.

Looks like you (cherry?) picked an image with exceptionally good contrast.

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#63

Post by baybal2 »

the__alchemist wrote: post #50
baybal2 wrote: post #23

I worked on a number of digital photo frames, including on ones like that. E-ink is not the most suitable thing for it in its current form. First, large size EPD cost an arm, and a leg, and custom one costs even more. Second, there are no 8 bit EPD controllers as of now a mortal can buy, which means grays look very bad. Third, there are inherent physical limitations which make increasing gray resolution of EPDs quite…

> E-ink is not the most suitable thing for it in its current form. What would you say is?

As I wrote above, from technical side, it is the great cost of i creasing gray depth

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#64

Post by userbinator »

baybal2 wrote: post #23

I worked on a number of digital photo frames, including on ones like that. E-ink is not the most suitable thing for it in its current form. First, large size EPD cost an arm, and a leg, and custom one costs even more. Second, there are no 8 bit EPD controllers as of now a mortal can buy, which means grays look very bad. Third, there are inherent physical limitations which make increasing gray resolution of EPDs quite…

Second, there are no 8 bit EPD controllers as of now a mortal can buy, which means grays look very bad.

Third, there are inherent physical limitations which make increasing gray resolution of EPDs quite hard. The precision you want, the slower would the refresh rate be.

For a digital picture frame, refresh rate isn't that important. In fact, a "gradual shading" on refresh might even make for a neat transition effect[1].

IMHO it's just the "cartel" (they like to keep the details of driving their displays confidential) of EPD controller companies who haven't produced controllers with more than 16 levels of grayscale, but the material is fundamentally analog and here is proof that if you drive the display directly, you can get at least 32 levels of grayscale if not more:

https://news.ycombinator.com/item?id=16140284

With a bit of careful calibration, I believe far finer grayscale is possible.

[1] Although EPDs have been around for a long time now, I have yet to see the demoscene do anything with them --- a directly driven display naturally allows for a lot of effects due to it effectively being an "analog write-only memory".

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#65

Post by gfxgirl »

"True Minimalism"

No, true minimalism would be doing without this needless frame.

I actually think it's cool though I'd want one much much MUCH larger. My comment is mostly about the smug comment at the end. It's not minimalism to clutter your life with a superfluous gadget

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#66

Post by Triv888 »

baybal2 wrote: post #36
leipert wrote: post #27

Earlier quoted context omitted.

What would you suggest for an affordable picture frame displaying digital art?

A second hand TV? Large size LCDs got ridiculously cheap with time. It may be cheaper to by a 40 inch LCD panel, than a 10 inch high-end Eink

Good luck running that for years on a battery...

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#67

Post by ISL »

cookingmyserver wrote: post #53
baybal2 wrote: post #37

Earlier quoted context omitted.

Note, they have dithering, and they likely went for the best one possible.

Interesting accusation. What attributes of this photo would lend itself to be of better quality in such a display?

(Disclaimer: I think this display is awesome -- can't allocate the funds for it right now, but will be keeping an eye on it going forward.)

The image is "contrasty", showing lots of hard transitions from bright to dark. With displays of low bit-depth, the hard thing to do is smooth gradients of tonality.

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#68

Post by svennek »

I found the image server, in the spirit of using your device for fun and interesting things (say nothing of privacy).. Why would you need the online converter, if you selfhost the image-server?

(potential customer here, but wanna use it not for pictures but for "daily status")

Re: I built a picture frame with a greyscale e-paper that runs on battery for years

#70

Post by adrianN »

dsr_ wrote: post #32
leipert wrote: post #27

Earlier quoted context omitted.

What would you suggest for an affordable picture frame displaying digital art?

If you can plug it into a wall, have a Raspberry Pi 4 series driving a 4K TV of the size of your choice. The cheapest one I see on Amazon right now is a 40" 4K HDR from Vizio, with quite a small bezel - $240. Hang it on a wall and paint the bezel white, or make a nice wood frame for it.

5W for the Pi, 60W for the screen is about 550kWh per year, or around 200kg of CO2 (give or take your local energy mix). That's about 10% of an average Indian's emissions.
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