Darkroom .... half of image pixelated when zoomed out

Software darktable
1

Hi,

DNG photos downloaded to Windows PC and added to Darktable. They show up fine in Lighttable.
Move over to Darkroom and one half each photo has a pixelated effect on it.
Zoom in, just a little bit and this effect disapears.
Zoom out, effect returns.
Very strange, is this a bug in Darktable or possibly a Windows conflict?
And help much appreciated.

Thanks
Ron

Screenshot 2023-04-29 183646

2

Which version of darktable and windows are you using? Also opencl or not, which graphics card, etc

3

Could you share the file so we can see if we can replicate it. I have never seen this sort of problem before.

4

Hi,

Thanks for your replies.

Darktable: 4.2.1
Windows: Windows 10 Pro, Version 21H2, OS Build 19044.2846.
Processor: AMD A8-6600K APU with Radeon HD Graphics 3.90 GHz
RAM: 8GB.

The effect is only on DNG files, JPEGs are not affected.
It’s a bit random, for example I can open a folder of and select a photo, the effect may not be present for this photo but after scrolling through the other photos in the folder the effect shows up on all photos. Weird!

IMGP0432.DNG (21.5 MB)

Have I got a setting wrong?

Thanks

Ron

5

I’m running dt 4.3.0+1435 on Win 11 and that image you shared seems to behave normally. (edit with OpenCL active)
Are you using OpenCL acceleration?

image
image1110×738 39 KB

And does the image still pixelate once you start making adjustments?
I’m no expert… just trying to think of relevant questions that might help isolate the issue :grinning:

Edit: tried it on my Win 10 laptop with no OpenCL and dt 4.0 - also fine.

6

Hi,

Many thanks. You are far more of an expert than me!

Making adjustments in Darkroom doesn’t make any difference.

Settings before:

Screenshot 2023-04-30 091845

After:

Screenshot 2023-04-30 104656
Screenshot 2023-04-30 104656784×536 53.2 KB

No difference.

Thanks

Ron

7

Try with OpenCL turned off.

grafik

8

Magic…that worked.

Many thanks for all your help, it was becoming quite irritating!!

Cheers

Ron

9

The only issue with OpenCL turned off is that some modules (edit: like diffuse or sharpen) will be much slower, at least if you do have a decent GPU for OpenCL to use.
Mind you, I happily used dt without OpenCL for a good while before splashing out on a GPU - YMMV.
I believe driver problems are often the cause of issues with OpenCL turned on, but my knowledge doesn’t extend much further than suggesting to check for updated drivers for your graphics card…

1 Like
10

maybe run

darktable -d perf -d opencl

from commandline to get a information, what’s happening and where there are limits.
‚Very fast GPU‘ doesn’t seem to be the best setting for this gpu configuration :wink:
Maybe spend some time with darktable 4.2 user manual - memory & performance tuning
Your system is quite limited, so don’t expect a wonder….

11

Hi,

Good program.
Thanks for the tips.

Ron

1 Like