Square artifacts in 1.9.O.820 when zooming

[Claudio60]

Zooming  in and out causes a sort of big rectangle/square artifacts in the entire image; it seems the picture itself is divided in different square/rectangle zones that differ in brightness one from each other (as the rendering wasn't complete in some of these "squares"). This issue doesn't occur if "Enable OpenCL compute acceleration" is set to  off.  My laptop has 2 graphic cards: AMD Radeon 7970m and Intel HD4000 both with latest drivers.

[Chris B]

Hi Claudio60,

Is it similar to this?

If so, can you try Ron P's file for me please?

[Claudio60]

Hi Chris, yes it's identical or very similar; in my system this issue appears working with .jpg files and not with every photos; I'm not sure but I think it happens on jpg with at least 4-5 adj levels but ONLY if you zoom in and out (sometimes the issue appears the first time I zoom in, other times after a few times of zooming in/out, in other photos doesn't appear at all);  anyway when this issue is visible on screen and I save the photo as .aphoto file, the "square artifacts/re-draw" are also saved in the file and are visible when I reopen it, but if I export the file as .jpg (when the issue is visible on screen) the exported .jpg file has no errors, no artifacts, re-draw or similar.

I tried Ron P's files many times zooming in and out, making some adjustements  both in develop persona than in  photo persona but I can't reproduce the issue in my notebook; the only thing I noticed is that when the .cr2 raw file is opened in develop persona the image is rendered washed out and with a color cast for 1-2 seconds starting/rendering in vertical lines from left to right before it renders with correct colors. 

PS: sorry for my poor english.

[Chris B]

Hey Claudio60,

Thanks for the info. We do seem to be getting a few cases of this. I've had it once or twice too. I'm assuming there's still a few teething problems with OpenCL which will continue to be sorted throughout the beta.