Author Topic: Just a picture of the subpixels...  (Read 516 times)

Daniel W

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Just a picture of the subpixels...
« on: March 25, 2020, 04:09:05 pm »
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Well, the title says it, and, as mentioned, it's a really cheap scope, so the image quality isn't that good. Yet, it reasonably illustrates the subpixel layout, which seems to be RGB with every other line (running vertical in this image - it was hard enough to get any image at all) pushed over 1.5 subpixels.

One "pixel" might consist of a little "RGB triangle", but that's just me guessing. I don't really know anything about how the display is driven. If anyone else here have anything to add, I'd be interested.

For some reason the blue subpixels on every other line seems to be brighter (to the point of appearing white in this image). The kind of stripey pattern (running horizontally in this image) seems to affect everything shown on the CoDi. I'm not sure if that's an artifact of my particular unit or whether it's universal. Does anyone else here see this (very fine) vertical stripey pattern on their CoDi?

Edit: Added a second example.
« Last Edit: March 26, 2020, 07:46:45 am by Daniel W »

Varti

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Just a picture of the subpixels...
« Reply #1 on: March 25, 2020, 08:18:01 pm »
Really interesting! Now I would love to see a similar pic of the main screen, too...

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Zarhan

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Just a picture of the subpixels...
« Reply #2 on: March 26, 2020, 04:13:44 am »
I don't see any patterns as such. I placed a white sheet in front of the camera and put the camera on CoDi and it's pretty much white with nothing visible to me...

Also, in the "home screen" where it just shows the clock and rest is black, the numbers...well, if I take out a *magnifying glass* I can see individual subpixels (or at least imagine them being there), but cannot really make out any stripes..

Daniel W

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Just a picture of the subpixels...
« Reply #3 on: March 26, 2020, 07:41:35 am »
Quote from: Varti
Really interesting! Now I would love to see a similar pic of the main screen, too...
While these images might not belong in the CoDi subforum, it felt weird to not post them in the thread in which the were asked for, so here they are. Please move them elsewhere, if appropriate.
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My cheap scope couldn't get a very good exposure, so I'm providing two examples each of text and graphics.

On a 403dpi screen, each subpixel (RGB segment) is roughly 0.021 x 0.063mm. As we can see, the segments are stacked in vertical stripes, rather than the more common horizontal arrangement. This is because the Cosmo main screen is just a regular 6" LCD RGB phone screen, built to mainly be used in portrait mode, but since the Cosmo is built to mainly be used in landscape mode, the subpixels ends up turned around 90 degrees. This, in turn affects the anti-aliasing of text. Clever anti-aliasing algorithms can use the individual subpixels to effectively triple the (usually) horizontal resolution, and improved horizontal resolution usually contributes more to text legibility than vertical resolution. That isn't to say that vertical subpixel text rendering would be pointless, but it offers less of an advantage. As far as I can tell, the Cosmo screen driver appears to do "whole pixel" text anti-aliasing.

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For graphics, the subpixel orientation matters less. While it would be possible to create subpixel optimized graphics, it would require knowledge about the particular screen it's to be displayed on, so it could really only work reliably for graphics generated locally on the device, say, by a game engine, but it would most probably prioritize more frames per second over greatest possible detail fidelity.

ZimbiX

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Just a picture of the subpixels...
« Reply #4 on: March 27, 2020, 07:21:48 am »
That subpixel array looks like it's a PenTile-like RGBW display - https://en.m.wikipedia.org/wiki/PenTile_matrix_family
I'd thought the CoDi imagery looked spotty, but hadn't realised it was this. Damn, I hate PenTile. Thank god it's not on the main screen!
« Last Edit: March 27, 2020, 07:23:41 am by ZimbiX »

Daniel W

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Just a picture of the subpixels...
« Reply #5 on: March 27, 2020, 07:53:08 pm »
Quote from: ZimbiX
That subpixel array looks like it's a PenTile-like RGBW display
While I share your disdain for PenTile, the subpixels appearing white in my pretty poor photos, are really blue, and just bright enough to saturate my really cheap sensor. Here's another attempt, this time blu-tacking (for distance) a handheld 30x magnifier to the CoDi and using a somewhat better camera:
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The subpixel array seems designed to create little RGB triangles. How they map to actual pixels, is anybody's guess, but there appears to be an equal number of R, G and B, which is typically not the case with PenTile arrangements. Still, though, I suspect something slightly weird IS going on. At least on my CoDi, the blue subpixels on every other line, are considerably brighter than the rest. Since I have no other CoDi to compare to, I can't tell whether that's by design, a slight hardware flaw in my particular CoDi or a software issue.
« Last Edit: March 27, 2020, 07:54:47 pm by Daniel W »