Inspiring

Answered

Weird Crop tool behaviour with 16-bit files

Forum|Forum|13 years ago
June 1, 2012
2 replies
25332 views

Shadow areas of my 16-bit files show strange patterns if I use the Crop tool to rotate. I can also replicate the problem by doing the following:

Make a new empty 16-bit file in PS6 in RGB mode (File>New). Fill it with 100% black. Use the Crop tool and rotate to taste. Press Enter to accept the crop and zoom in to enjoy the black and grey noise patterning reminiscent of a man's suit. The Straighten tool will achieve the same result. Your suit pattern will vary according to the degree of rotation.

The problem goes away if you subsequently convert the file to 8-bit, or convert to any other mode (Greyscale, Lab, CMYK).

This patterning is easily visible at 100% view or less, and appears whether the View>Show>Pixel Grid option is on or off. It is decidedly NOT the pixel grid I am seeing.

This effect can be created with files from both my Canon and Hasselblad cameras.

I'm using a Mac Pro with OS10.6.8.

This topic has been closed for replies.

Correct answer erickellerman

There is in implicational order at work: If 'Use Graphics Processor' is selected in Preferences>Performance, then not checking [ ] Delete Cropped Pixels produces the effect. If 'Use Graphics Processor' is not selected (after restarfting PS), then it doesn't matter whether 'Delete Cropped Pixels' is selected or not.

Bingo! If I download my .psd file, and then open it in PS6 with 'Use Graphics Processor' unselected, guess what? Yes, NO patterning! So UGP is the cucial element.

Noel Carboni

Legend

13.0.1 Update

I cannot reproduce this problem with the 13.0.1 code and ATI Catalyst 12.8. I'm wanting to call it fixed in all facets.

Anyone else care to try?

-Noel

Message was edited by: PECourtejoie

E

erickellermanAuthor

Inspiring

I'm a Mac user, so I am testing 13.0.1 under different circumstances than yours, Noel. I report no change. The suit patterns are still there.

Noel Carboni

Legend

Just to be clear, the patterns you saw were getting generated into the files you were saving. Have you recreated them from what should be smooth data using only 13.0.1?

-Noel

Chris Cox

Legend

Which version of Photoshop are you using?

And which options for the crop tool?

E

erickellermanAuthor

Inspiring

Hello Chris

I'm using PS6. I invoke the Crop tool, Unconstrained, Delete Cropped Pixels unselected. Degree of rotation doesn't matter, though the pattern noise will vary with the degree of rotation.

I have now discovered that this weirdness ONLY happens with crop rotation of 16-bit files. If I open a 32-bit file and rotate, there is no patterning. If I convert this rotated crop to 16-bit, there is no change. But if I convert the file to 16-bit and THEN rotate, I get the noise again. 8-bit files do not show this behaviour. Saving rotated 16-bit files to TIFF and PSD preserves the patterning. Converting these files to jpeg (8-bit, obviously) removes the noise.

Noel Carboni

Legend

This is fascinating, but has actually become too technical for me. My question is, is this now a Photoshop problem that needs solving, or is it just my and others' bad luck?

The first of the two is almost certainly a Photoshop problem. The other may be rooted in how Photoshop is using particular video cards, or maybe a bug in your display driver that may be able to be solved by seeking an updated version and downloading/installing it from the web site of the maker of your video card. It certainly seems that some people have display subsystems that don't show the problem.

In either case you have the attention of one of the more senior Adobe engineers, so there's not much else you need to do to get Adobe working on it.

Something to try as a test: Go into your Preferences - Performance dialog, select the [Advanced Settings...] button, change the Drawing Mode to Basic, then quit and restart Photoshop. Do you still see the problem, and do you still have all your GPU-accelerated functions?

-Noel

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