Stenis
(Sten-Åke Sändh (Sony, Win 11, PL 6, CO 16, PM Plus 6, XnView))
1
I just asked Char GPT 5 what really happens in Photolab when we disable Open CL as some have suggested in order to try to avoid system crashes.
Here is the detailed answer:
What OpenCL does in PhotoLab
OpenCL (Open Computing Language) is a framework that lets software run certain tasks on the GPU instead of the CPU. GPUs are great at parallel processing — doing thousands of small operations simultaneously — which is perfect for:
Local adjustments and previews (masking, tone equalization)
Image exports and rendering
When OpenCL is enabled, PhotoLab sends these heavy calculations to your graphics card — usually much faster than your CPU could manage.
When you disable OpenCL
You’re essentially telling PhotoLab, “Don’t use the GPU — run everything on the CPU instead.”
What that means in practice:
Noise reduction (DeepPRIME/XD): The biggest hit. Rendering/export times can go from seconds to minutes per image, depending on your CPU.
Mask previews and brush lag: You might notice slower or stuttery updates when painting masks or zooming/panning high-res files.
Overall performance: Exporting batches of RAW files or viewing corrections in real time will feel more sluggish.
The only real benefit is stability: if your GPU driver is buggy (and recent NVIDIA–DxO issues have proven that’s possible), disabling OpenCL can stop random crashes, black previews, or export errors.
When disabling OpenCL might make sense
You’re troubleshooting driver instability or AI masking crashes (especially with older RTX cards or mismatched drivers).
You’re working on light edits or JPEGs where GPU acceleration gives little benefit.
You’re testing CPU-only performance to benchmark export speed.
# How is the OpenCL function utilised with DxO PhotoLab?
This information applies to all versions
When activated in the preferences, OpenCL is used for rendering export images, as well as for displaying RAW previews when the zoom level is above 75%. This is only the case if our benchmark has determined that OpenCL performance is superior to CPU processing.
So, not quite the same as the AI that you used.
My experience is that, in this regard, OpenCL does not make a difference in the actual processing as mentioned above. Rather, turned OFF seems to allow PL9 to function with less than optimal GPUs. However, the GPU is still used. It is Not disabled.
This is what I said in this thread
"As I mentioned previously, PL9.02 did not work on my Office computer whereas, PL9.01 did.
I installed PL9.1 and unchecked OpenCL and it works. No crashes.
I think OpenCL is part of the problem as it was enabled when I did the test with 9.02."
.
So, it appears that with OpenCL OFF, my Office computer is working properly even with the preset AI masks.
With images that have masking but not AI masking, the export times are the same as PL7 where OpenCL was ON.