convert PNG bilevel images with jbig2decode rather than flatedecode #70

By wizard on 2020-04-11T03:57:18.771Z

Bilevel images are widely used for scanned ebooks. Plz do so to explicitly reduce sizes.

By josch on 2020-04-11T06:49:15.782Z

I experimented with choosing the right encoder for bilevel images at around the time when I started writing img2pdf as is evident from the age of the file test_comp.sh from 2012.

But my tests didn't show a great advantage of using jbig2decode over first using png's paeth filter and then a flatedecode.

But maybe the kind of images I had is wrong -- do you have images of a different type where jbig2decode indeed produces significantly smaller images?

By josch on 2020-08-04T07:04:58.094Z

Hi @wizardforcel, I just wanted to ping you about this issue because I'm making a new release soon and was wondering whether you indeed have some input where jbig2decode provides a significant advantage over the current implementation. Otherwise, please close this issue. Thanks!

*By wizard on 2020-04-11T03:57:18.771Z* Bilevel images are widely used for scanned ebooks. Plz do so to explicitly reduce sizes. --- *By josch on 2020-04-11T06:49:15.782Z* --- I experimented with choosing the right encoder for bilevel images at around the time when I started writing img2pdf as is evident from the age of the file `test_comp.sh` from 2012. But my tests didn't show a great advantage of using jbig2decode over first using png's paeth filter and then a flatedecode. But maybe the kind of images I had is wrong -- do you have images of a different type where jbig2decode indeed produces significantly smaller images? --- *By josch on 2020-08-04T07:04:58.094Z* --- Hi @wizardforcel, I just wanted to ping you about this issue because I'm making a new release soon and was wondering whether you indeed have some input where jbig2decode provides a significant advantage over the current implementation. Otherwise, please close this issue. Thanks!

Closing because of inactivity.

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convert PNG bilevel images with jbig2decode rather than flatedecode #70