Editing problems Late 2015 iMac

Started 6 months ago | Discussions thread
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James C. Murray Senior Member • Posts: 2,083
Editing problems Late 2015 iMac


Late 2015 27inch 5K iMac on Big Sur.

4Ghz Quad I7, 16 GB Ram, 512 SSD.

Graphics, AMD Radeon M395 2GB.

Problem, editing Sony A7R3 Raw files using Capture One 2021.

When adjusting sliders involving Exposure, Dynamic range, Clarity and sharpening the screen brightness goes up very high for a moment before returning to where the adjustment should have put it.

Ocasionaly this brightness is accompanied by artifacts on screen of geometric blocks, (rectangles, series of small blocks that are blackened out with no consistency, etc.). These artifacts are fairly short lived and the screen returns to what I would expect but it makes editing pretty hopeless.

If I take a file through Topaz Denoise AI and try to further edit the Tiff that Topaz produces, (around 70MB), the problem is significantly worse.

I have looked through Capture One’s site and tried their recommendation about resetting the hardware acceleration, (Open CL in the preferences), with no real improvement.

I keep my catalog and images on an external SSD and I am aware that it is best to keep the catalog on an internal but my catalog and previews will not fit on to my internal drive.

I have tried creating a separate small trial catalog with previews and files on the internal SSD with the idea of seeing if data transfer speed might be significant but with no real difference in the problem.

So I am left wondering if the problem is due to my system reaching its limits, with the Graphics card and 5K monitor, the software becoming too demanding, or is something starting to fail?

I did have to replace the motherboard on the iMac some months ago but I don’t know if that could have anything to do with it.

I would be grateful for any thoughts or advice.

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