What you’re experiencing is a cocktail of confusion on several levels:
- Don’t do this test using raw images. A raw image cannot just be shown, it must first be cooked. It’s like a refrigerator full of raw stuff and a recipe, it’s not a ready meal. Lightroom’s interpretation of a raw image is different to RawTherapee’s interpretation, Lightroom does a bunch of stuff to the image by default including sharpening which RawTherapee does not do by default. That’s why you should perform this test using a non-raw file.
- RawTherapee’s sharpening and noise reduction tools only affect the preview at a zoom level of 100% or more.
- RawTherapee is not HiDPI-ready, i.e. none of us developers have HiDPI screens and so it probably doesn’t perform optimally on such screens. When I simulate a HiDPI screen using scaling, everything in RawTherapee including the thumbnails and main preview are also upscaled.
Scale=1
Scale=2
