Open CL - What happens when disabling it?

[Allan]

@Stenis

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:

• DeepPRIME and DeepPRIME XD noise reduction
• Lens corrections (distortion, vignetting, chromatic aberration)
• 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.

---

This is what DXO says

# 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.

---

---

@Stenis

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.

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

PL9 on older computers

I have two Computers - my 6 year old “Office” computer and my 5 year old “Graphics” computer. The Graphics was just updated to Win11. Office = 28gb i5-8400 CPU GTX 1060 WINDFORCE OC 6GB, Driver 560.94 Graphics = 32gb i5-10400F CPU GTX1660 Super, Driver 511.09 As you can see, neither meet the min requirements for GPU and have old drivers, however… I processed 28 photos each with several AI masks and sub-masks with Deep Prime 3. I find AI “add an area” to be almost instantaneous and very accu…

"As I mentioned previously, PL9.02 did not work on my Office computer whereas, PL9.01 did.

Office = 28gb i5-8400 CPU GTX 1060 WINDFORCE OC 6GB, Driver 560.94

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.

Allan