PHOTOSHOP: Horizontal and Vertical (plaid like) lines appearing in shadows on MacOS 10.10 Yosemite

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  • Updated 3 years ago
  • (Edited)
I'm experiencing very strange horizontal and vertical lines (very plaid like) issues in Photoshop CC 2014.2.2 release. They appear in the shadow areas of image files after doing something like transform, rotate, etc. Also appear after doing photomerge in auto & other modes, but not in "reposition" mode. So it makes me think it has something with the files being skewed or modified in that way. Any knowledge on this? I'm really frustrated and spending WAY too much time trying to diagnose and fix.

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Blaine Franger

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  • very frustrated

Posted 3 years ago

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Blaine Franger

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Another example photo. Hard to see in the 2nd example above.
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Adam Jerugim, Employee

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Hi Blaine,

This looks like a display issue, likely caused by some GPU setting in Photoshop. If you could run some tests for me to see what's causing this, that would be a big help.

The first thing I need to know is what OS and hardware you're using and what's your video card/GPU?

Now go to Preferences > Performance and click on the Advanced Settings button in Graphic Processor Settings. Try changing that setting from Advanced to Normal and from Normal to Basic (restart the app after each change) to see if changing that setting helps. If not, try disabling OpenCL. If that doesn't help, try disabling the GPU altogether by unchecking "Use Graphics Processor".

What you're seeing almost appears to be the pixel grid - something that shouldn't appear at 100%, but should appear at somewhere around 800% magnification (depending on how large your image is). Disabling the GPU will disable the pixel grid as well.

Please let me know if any of this helps.

Thanks,
Adam
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Blaine Franger

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Hi Adam,
Wow, thanks for the quick reply and information. Much appreciated.
I'm using a brand new computer, the 27" retina iMac, OS X Yosemite 10.10.1
Processor: 4 GHz Intel Core i7
Graphics: AMD Radeon R9 M295X 4096 MB

I did some additional testing, and I think you're exactly right about it being the pixel grid. I've never heard of this happening before.
The lines are visible in most all files from 50% magnification all the way to 800%.
I did some additional testing and noticed the lines go away if I flatten the image (at any magnification).

So basically I'm realizing the lines aren't actually in the file, but rather its just a strange issue with the display/and graphics processing?
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Chris Cox

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I bet the lines go away if you convert to 8 bit/channel.

That looks a LOT like an old (like 2 years ago) bug in video card drivers that caused amplification of the low order bits in 16 bit/channel images. But that was only on Windows, not on MacOS - and it was fixed in driver updates.
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Blaine Franger

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Yes it does go away if I go into 8 bit. Strange, since this is a brand new MacOS machine.
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Chris Cox

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Yep, it's the shader implementation in the GPU driver.
Try setting the Photoshop GPU mode to "basic", restart, then open a 16 bit image. (that gets rid of the shader usage)
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Blaine Franger

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Hi Chris, yes you're right, setting the GPU to basic took care of the issue. Do you know if this issue will be addressed by Apple or Adobe?
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Chris Cox

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Thanks - that confirms the nature of the bug, as I suspected.

We'll investigate. Last time it was fixed in a driver update. But we'll have to see if we can work around it or if we have to wait for Apple to fix it.
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Adam Jerugim, Employee

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Yes, what you're seeing is the pixel grid and it isn't part of the image itself - it is an overlay to help identify individual pixels in the image when zoomed in.

The first thing I'd suggest you do is update to OS 10.10.2. It would be worth trying to see if that would help mitigate the display-specific issue you're seeing.
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Chris Cox

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But that only applies while zoomed in. Look closely at the artifacts, and the zoom level shown in the document tabs (100%).

This looks a LOT like the old driver shader bug in 16 bit/channel images.
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Chris Cox

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And from the diagnostics above, it's a shader bug.
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Blaine Franger

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Just updated to OS 10.10.2 and it didn't change anything, bummer.
Any other suggestions?

It's annoying seeing all that there when I'm at 50% or closer, but very relieved it's not actually in the file.

Thanks for the info so far.