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> Just a picture of the subpixels..., ...taken with a $4 fleamarket USB microscope.
Daniel W
post Mar 25 2020, 12:09 PM
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Attached File  CoDi49.jpg ( 191.47K ) Number of downloads: 13
Attached File  CoDiKeepass.jpg ( 205.26K ) Number of downloads: 6

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.
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Varti
post Mar 25 2020, 04:18 PM
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Really interesting! Now I would love to see a similar pic of the main screen, too...

Varti
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Zarhan
post Mar 26 2020, 12:13 AM
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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..
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Daniel W
post Mar 26 2020, 03:41 AM
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QUOTE(Varti @ Mar 26 2020, 01:18 AM) *
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.
Attached File  MainScreen1.jpg ( 182.03K ) Number of downloads: 3
Attached File  MainScreen1b.jpg ( 199.55K ) Number of downloads: 2

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.

Attached File  MainScreen2.jpg ( 163.58K ) Number of downloads: 1
Attached File  MainScreen2b.jpg ( 168.52K ) Number of downloads: 1

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.
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ZimbiX
post Mar 27 2020, 03:21 AM
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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!
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Daniel W
post Mar 27 2020, 03:53 PM
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QUOTE(ZimbiX @ Mar 27 2020, 12:21 PM) *
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:
Attached File  CoDiCloser.jpg ( 99.41K ) Number of downloads: 3


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.
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