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 hard. The precision you want, the slower would the refresh rate be.
If somebody is old enough to remember, (saying this as a 30 years old is indeed amusing to myself) the last active matrix monochrome LCDs had 8 bit, and more of gray resolution, but they are all discontinued now, or cost an arm, and a leg as "medical imaging" specialty.
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.
(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.
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:
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".
On the second point, my experience comes from a Kobo Glo HD eReader, but the rendition of photographs is very good - cliché, but its like a printed page. Line art obviously works best because its bold and high contrast, but colour digital art and black and white photographs all display very well in my opinion.
The difficult bit is making it not look like a screen. Even the fancy Sony "the frame" (which are supposed to do clever matching to room brightness etc) TVs don't get that quite right, and only do it in some special mode...
The costs in electricity bill is gonna be big compared to e-ink. Refresh rate of static picture can be terrible, OK for this use case. There's also color e-ink devices, though not many, and the colors were IMO too pastel-ish.
Although backlight of a second hand TV might also be dying, I agree say Chromecast on TV gives a nice effect. My oldest kid gets impressed, FWIW.
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.
I agree that the poor contrast etc of EPDs hurt them, including in this area. I'm questioning what you think are better alternatives for this use; I don't think there are any that don't have flaws worth weighing.
I thought Amazon held them, my bad. I was interested in this space around the time of the Kindle Fire release. It seemed to me like they just didn't want to chase a form factor that couldn't sell 90% of their media. So maybe there is a way, but no will.
Thanks. That's pretty awesome. Looks like they did run into the issue of no data sheets and had to hack around to get/make the driver for updating the screen, which is what I expected. Hope they keep improving it! And at $15 that's a great price. I paid more for a 2.5"x1" display but I needed the friendly pi integration.
Comments
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 hard. The precision you want, the slower would the refresh rate be.
If somebody is old enough to remember, (saying this as a 30 years old is indeed amusing to myself) the last active matrix monochrome LCDs had 8 bit, and more of gray resolution, but they are all discontinued now, or cost an arm, and a leg as "medical imaging" specialty.
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.
Note, they have dithering, and they likely went for the best one possible.
They == the ArtFrame's built-in software ;) What I posted was generated by the device. It is an example of the actual picture quality.
Yes, with a specifically chosen image.
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.
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".
EPDs are highly, highly nonlinear in their driving response.
It for a good reason full info behind making LUTs for driving EPD screens is kept as high secret.
On the second point, my experience comes from a Kobo Glo HD eReader, but the rendition of photographs is very good - cliché, but its like a printed page. Line art obviously works best because its bold and high contrast, but colour digital art and black and white photographs all display very well in my opinion.
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
The difficult bit is making it not look like a screen. Even the fancy Sony "the frame" (which are supposed to do clever matching to room brightness etc) TVs don't get that quite right, and only do it in some special mode...
The costs in electricity bill is gonna be big compared to e-ink. Refresh rate of static picture can be terrible, OK for this use case. There's also color e-ink devices, though not many, and the colors were IMO too pastel-ish.
Although backlight of a second hand TV might also be dying, I agree say Chromecast on TV gives a nice effect. My oldest kid gets impressed, FWIW.
Good luck running that for years on a battery...
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.
40" is massive for a picture frame
When you don't like the pictures, you can change them.
You can give them special frames and mattes.
You can show 36 Views of Mount Fuji all at once, and then two at a time.
And you can watch Netflix on it later.
If you keep your photos in Google Photos, I found the Nest Hub quite nice, since it automatically rotates among your recent photos
(It also automatically dims or blacks out the display when it's dark)
At what point does it become mandatory to refer to your own age in a self-deprecating way if it happens to come up?
What would you say is?
As I wrote above, from technical side, it is the great cost of i creasing gray depth
I agree that the poor contrast etc of EPDs hurt them, including in this area. I'm questioning what you think are better alternatives for this use; I don't think there are any that don't have flaws worth weighing.
Despite all this, E-ink's biggest problem is that Amazon owns all the tech and doesn't want to ever see it succeed.
Can you elaborate on that? As far as I know, E ink corporation and related patents are owned by a Taiwanese electronics manufacturer [0].
[0] https://en.wikipedia.org/wiki/E_Ink#Company_history
I thought Amazon held them, my bad. I was interested in this space around the time of the Kindle Fire release. It seemed to me like they just didn't want to chase a form factor that couldn't sell 90% of their media. So maybe there is a way, but no will.
you mean being relegated being used for price tags in whole foods isn't succeeding? I really want some of those and the ability to updated them.
Maybe you've already seen: https://hackaday.com/2020/11/27/repurposing-large-electronic...
Thanks. That's pretty awesome. Looks like they did run into the issue of no data sheets and had to hack around to get/make the driver for updating the screen, which is what I expected. Hope they keep improving it! And at $15 that's a great price. I paid more for a 2.5"x1" display but I needed the friendly pi integration.