Package: gscan2pdf Version: 2.8.2-1 Threshold function is extremely slow - Unusable - Possible regression
Applying threshold on a scanned image is extremely slow. Doing the same transformation using mogrify/convert is many times faster. This seems to be a regression during the last few months since this did not seem to be a problem before. Example test to reproduce: Scan one page, letter size, greyscale, 600pdi Tools > Threshold > Selected > 50% gscan2pdf process uses one cpu core at 100% for 2 minutes The same processing using "mogrify -threshold 50% %i" takes 2 seconds. Possibly gscan2pdf has a problem that is related to mogrify on the original format. If I remove the gscan2pdf option to automatically convert to png, restart gscan2pdf, scan and use "mogrify -threshold 50% %i", the processing time very long, just like gscan2pdf. Thus, it might be an issue with underlying mogrify libraries (if gscan2pdf uses them). ImageMagick issue #1819 seems might be related. https://github.com/ImageMagick/ImageMagick/issues/1819 Temporary workaround: Tools > Preferences > General Options > User Defined : "mogrify -threshold 50% %i" Tools > User Defined > "mogrify -threshold 50% %i" Version info: apt search gscan2pdf gscan2pdf/testing,now 2.8.2-1 all [installed] uname -rv 5.7.0-2-amd64 #1 SMP Debian 5.7.10-1 (2020-07-26)
