Leon Bottou

Image rendering differs between Qt5 and Qt6 builds.

When the Qt6 reports that the screen implements high dpi scaling ("retina"-style displays), djview , djview generates an image with a higher resolution that matches the true number of pixels and uses this by bypassing the high dpi scaling code. This gives a higher quality image. For me, this works as expected. The QT_ENABLE_HIGHDPI_SCALING=0 variable disables all this behavior, so that Qt6 matches Qt5's lower quality image. This could be useful to save cycles or memory.

DJview4 won't open djvu document online

It's interesting that wget can download it as text/plain without problem You got lucky. According to the standard, content of mimetype text/plain should encode line breaks as CRLF. So a web server running on Unix might very well convert all LFs to CRLF on the fly. On the other hand, a web server running on Windows would not do this. I rather have djview complain in all cases rather than show a mysterious bug later.

Not the same experience here. Things seem to work well under both Sonoma and Sequoia. Short of a reproducible crash, this is hard to debug.

.pc file does not work on MinGW

The mask extracted with ddjvu is not binary, but greyscale

djvm -l cannot handle output from cjb2