Photoshop 2020: Transparency display glitch - v. 21.0.3, macOS High Sierra

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  • Updated 6 months ago
  • (Edited)
I have recently noticed a new erroneous behaviour when previewing transparent objects against the transparency checkerboard in Photoshop. As long as there is an opaque background, all objects are displayed and blended properly, but when previewed on the transparency checkerboard, there is heavy banding apparent. The problem is only when previewing in PS, exported images (i.e. PNGs) display correctly with other software.
I have tried it on several other iMacs with same results.
Turning off HW acceleration or switching to legacy compositing did nothing.
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Sini .

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Posted 6 months ago

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Michael Madsen

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This is normal behavior as a result of the way PS renders layers - AFAIK  there's currently (and have never been for that matter) a way to reliably see dithering / grads on trans backs. Its been this way as long as I can remember. 
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Sini .

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Seems a bit counterintuitive. If the image can be propperly displayed on a white background, how come it cannot be on a checkerboard one?
And I am not talking about the regular banding betwen levels, I get that. I am talking about the glitchy artefacts that appear between transparent objects on the checkerboard. That is new behaviour. Illustrator, or Gimp for that matter, do not seem to have the same problem, so I wouldn't just write it of as a dithering inevitability. 

Furthermore, on an advice from a coleague I have tried pushing the same image to 16 bits/channel, to no avail. BUT when converting to 32 bits per channel, everything started behaving as I was expecting it to in the first place. No more erroneous glitching between transparent elements.

I am pretty certain these glitches should not be and have not always been there (at 8bpp).

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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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Can you post your sample files for us to troubleshoot?
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Sini .

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Certainly.
It's not the exact same the same file, but it captures the gist.
I hope a Wetransfer link will do: https://we.tl/t-UQyr1KGeKq
(800x800 px PSD 2.1MB 8bpp sRGB)
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Michael Madsen

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Sini : you're absolutely right - it prob should be fixed!  Maybe im just too accustomed to PS behavior :-) maybe a bug not a feature - ive been working prof with PS since version 1.0 and remember distinctly this behavior going back decades and ppl complaing bout this - i could be wrong - tested with the last 4 point PS vers. and its all the same. pretty weird id Jeff dont know bout this?