I was working on scan of this "a little" overexposed analogue photo (cleaning from dust, some colour adjustments and curves). After saving a picture, this check pattern appear. I tried different formats - effect was the same. I only came to the conclusion that the appearance of this pattern is associated with flattening the photo.
Left picture is screenshot from open PS project just before flattening/saving as. Right is after. No actions between.
Here original unedited raw scan:
Scan, after some lightroom adjustments, before i move with it to edit in PS:
My layers in PS:
(working with colors and contrast, no sharpening, scaling etc)
And here are enhanced lines in: 1.before PS 2.after saving as/flattering in PS 3. screenshot from open PS just before saving as/flattering
How to get rid of it?
I work in tiff RGB 16B