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Photoshop and GPU: Blurry Image Scaling Damages Image Assessment Workflow

Update Jan 2017: Adobe has still not addressed this issue, although I made suggestions that solve the problem trivially without even having to modify any GPU code:

  • Fit to Window should scale only to a supported GPU scaling factor instead of blindly fitting exactly to the window. Why not? It’s already buggy in adding excessive margin space around the image.
  • Letting the user define desired scaling factor(s) so that cmd-0 Fit to Window uses that scaling for a clean rendition. Why are things hard-coded as they are?
  • Just let the user redefine the cmd-0 shortcut to scale to some desired factor: 50%, 33%, 25% — and make darn sure the GPU has a high quality version at that scaling factor.

Back in November 2014 I reported on blurry image scaling in Photoshop with the GPU enabled. This issue has not been addressed even here in November 2015.

For my work in assessing images, I must be able to see a non-blurred image at Fit on Screen when I evaluate my images in Photoshop CC 2015. Because of this bug, I am forced to disable the GPU. Which mean impaired performance for a variety of operations.

Specifically, Fit to Screen on a 2560 X 1600 display results in a blurry image with large digital files. This makes it impossible to assess batches of images without a time-wasting zoom in/zoom out hassle. And it is not a pleasure to look at a blurred image, if not an outright eyestrain.

Photoshop allows enabling or disabling GPU support in Preferences => Performance => Graphics Processor Settings.

Different cache levels and GPU settings are all broken. GPU support is just plain broken for zooming in Photoshop; some zoom levels are sharp and others are awful. Actual pixels is fine of course, but then one cannot see the image as a whole. Surely a fast GPU can render a reduced size image far better than is being done (dual GPUs in Mac Pro!). But I’m told by Adobe that fixing this is not easy. But since when is such a damaging bug acceptable for three years in an image editor?

Note that the GPU blur depends on the amount of zoom relative to screen and image size, so a different size image or display might be fine for some users. And indeed some zoom levels are reasonably sharp—but never Fit on Screen with my typical images.

I reported this to Adobe over three years ago, but nothing has been done.

Update: in a frustrating twist for my work, support for 10-bit color requires that GPU support be enabled. So I get blurry images and 10-bit color, or sharp images and 8-bit color.

The image below is a crop of the whole. Observe the blur with GPU enabled and sharp image with the GPU disabled (toggle). Click for a full size image.

Photoshop CC 2014 image scaling, GPU on/off
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