Weird Artifacts when rotating

[CallumGGibson]

After doing a very small rotation to get the horizon level. Doing so shows a "grid" of sharper and blurred boxes. It is repeatable in different images and seems to matter how much of a degree the image is rotated. I'm not sure if this is just an unfortunate side effect or an actual issue.

[Trevor.Dennis]

Are you referring to the horizon on the left of the image?  If not, can you tells specifically where you are seeing the problem?

I don't actually know what interpolation ACR uses when resampling RAW files, but you could try leaving the horizon skewed untill you open the image inside Photoshop, and using Free Transform to straighten it.  That way you can control what Interpolation is uded from the Options bar.

[davescm]

Sharpening at 150 !!!!!   No wonder you can see artifacts. .

Seriously - if an image needs that much sharpening, try less sharpen and increase local contrast (clarity slider) and see if that works better with less visual artifacts.

Dave

[CallumGGibson]

Its at 150 to show the problem more. I'd never have it that high ever! You need to zoom in at 100% to clearly see it.

[CallumGGibson]

Just zoom straight into the middle. The sea is where it's the most clear.

[davescm · Accepted solution]

Ah - that explains that - and yes I can see it.

Can you try something? Go to Preferences - Camera Raw and turn off Use Graphics Processor. Then open your image and repeat the rotation above.

Dave

[CallumGGibson]

Yep absolutely just not there anymore! Why would it be doing that?

[davescm]

In theory the GPU processing speeds things up. In practice, for camera raw, I can't see a difference in speed and depending on the implementation of the GPU routines on your particular card it can sometimes introduce artifacts or even crashes. Whilst I always have the GPU checked in Photoshop , for camera raw I leave it off.

Dave

[CallumGGibson]

Okay was not aware of such things. Shame I'll have to turn it off, the GPU helps so much. Thanks for the info.

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Weird Artifacts when rotating

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[davescm]

Don't turn it of for Photoshop, just for Camera Raw. I doubt you will notice a speed difference.

Dave

[CallumGGibson]

There is quite a difference, less so when changing sliders, but when zooming in or out, it can take a second to resample. Funny, as Lightroom doesn't care either way.

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Saturday, 16 December 2017, 11:02pm +00:00 from davescm forums_noreply@adobe.com<mailto:forums_noreply@adobe.com>:

Weird Artifacts when rotating

created by davescm<https://forums.adobe.com/people/davescm> in Photoshop General Discussion - View the full discussion<https://forums.adobe.com/message/10046297#10046297>