Created attachment 136666 [details] a sample original file SUMMARY Opening and editing a jpg image file in Krita results in a slightly blurred image. STEPS TO REPRODUCE 1. Open a jpg image file and make some minor edits on it (except blurring). 2. Save the file with a different name. 3. Compare the original and edited files in any image viewer. OBSERVED RESULT The image file edited and saved in Krita is slightly blurred in comparison to the original. EXPECTED RESULT Krita should not make any changes in the image other than those made by the user. SOFTWARE/OS VERSIONS Operating System: Kubuntu 20.10 KDE Plasma Version: 5.19.5 KDE Frameworks Version: 5.74.0 Qt Version: 5.14.2 ADDITIONAL INFORMATION
Created attachment 136667 [details] a sample edited file, slightly blurred
Hi, Resaving jpegs always blurs them, it's part of the lossy compression that is inherit to jpeg (You can find others confirming this if you do an internet search for 'resaving jpeg'). You need to either save as PNG, or if you must use jpeg, turn up the quality to the highest setting.
(In reply to wolthera from comment #2) Oh, sorry! I haven't noticed this for years probably because I've never bothered to edit my digital photos before. Thanks for the tip.
(In reply to wolthera from comment #2) Hi again, I've confirmed what you've said, but still curious as to how come I haven't noticed this in years although I've rarely edited digital photos, I've checked what happens in GIMP, and just saw that the said degradation in re-saved jpg files is not noticeable in GIMP as in Krita, even with a compression level lower than 100% (my default setting is "use quality settings from original file" which was 85% in this case) as you can also see in the third sample I'm attaching now. So, I think Krita needs to improve on this matter (as well as a couple of other features) in order to be on a par with GIMP.
Created attachment 136690 [details] a sample edited file, not so blurred in GIMP
Can you take the same original jpg (it would be best to use the file you already attached here) and save it in both Krita and Gimp with the exact same quality (I guess 85% will be good) without any changes and compare and attach the results here?
Ahh and note that in Krita there is the Advanced Quality tab. You might want to check that one too. It might be that Gimp by default uses the best quality subsampling and Krita uses the smallest file/lowest quality one...
(In reply to Tiar from comment #7) It seems you're right. Default advanced options are different. Subsampling GIMP: 4:2:0 (chroma quarted) vs Krita: 2x2, 1x1, 1x1 (smallest file) Although both are the lowest and not the best quality options, they look different to me, and I suspect this might affect the result. Smoothing GIMP: 0% vs Krita: 100% Perhaps this might affect the result. I did save an image without making any changes in both apps after selecting the same settings (100% quality, best quality subsampling, and 0% smoothing) and the result was that all three files looked exactly the same. So my conclusion is that yes, this is not a bug. However, it seems Krita should have better default configuration (especially advanced options) so that an average user gets a result similar to GIMP: more or less the same file size, but without any noticeable degradation in jpg files.