1.9.5 JPEG-li and Estimated quality
Posted: Sat Nov 01, 2025 11:51 pm
potentially dangerous behavior of 'Estimated quality'
for example:
i have a PNG file and i want to save it as JPEG
i select 'Save as' and in 'Options' I check 'Use JPEG-li' and set 'Quality' to 90
now I have a 185KB file, and 'Info' pane shows that 'Estimated quality' is only 57 (which is baffling)
i close the file
i reopen it
now I select 'Save as' and in 'Options' I uncheck 'Use JPEG-li' and check 'Use estimated quality'
now I have a 114KB file and 'Info' pane shows that 'Estimated quality' is also 57
but the quality of the file is now much worse because '57 quality of JPEG' and '57 quality of JPEG-li' are quite different qualities
i think XnView must somehow distinguish the files by their compression codecs and recalculate 'Estimated quality' accordingly
so that we do not accidentally downgrade our images
for example:
i have a PNG file and i want to save it as JPEG
i select 'Save as' and in 'Options' I check 'Use JPEG-li' and set 'Quality' to 90
now I have a 185KB file, and 'Info' pane shows that 'Estimated quality' is only 57 (which is baffling)
i close the file
i reopen it
now I select 'Save as' and in 'Options' I uncheck 'Use JPEG-li' and check 'Use estimated quality'
now I have a 114KB file and 'Info' pane shows that 'Estimated quality' is also 57
but the quality of the file is now much worse because '57 quality of JPEG' and '57 quality of JPEG-li' are quite different qualities
i think XnView must somehow distinguish the files by their compression codecs and recalculate 'Estimated quality' accordingly
so that we do not accidentally downgrade our images