Originally posted by GUB Do you get the same result if you set the same settings as I did?
With one browser, I get the same horizontal line in the magenta/pink area as you do, but not the differently coloured areas in the cyan/blue patch.
With another browser (Firefox), I don't get any artefacts at all.
Interestingly, the two different browsers render the noise differently as well. My first guess would have been different scaling approaches, but with these images, there shouldn't be any scaling involved. Perhaps there is (see below). My next guess would be a difference in colour management. The artefacts in the K-1 samples are very weird, though. I very much doubt they have anything to do with the camera.
If you right-click on the K-1 patches with artefacts and select "View Image" you'll probably see an artefact-free version of the patch. The resulting framing doesn't quite make sense to me, but the patches seem clean then.