[Bug 1992228] [NEW] Fax/PDF performance regression compared to focal

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Julian Andres Klode (juliank):

I'm regularly using `convert` to turn a line-art PNM file to a PDF with
Fax/Group4 compression.

This used to take a few seconds on focal.

I updated to jammy and it takes almost 5 minutes now!


$ time convert -verbose scan.pnm -compress Fax scan.pdf
scan.pnm PBM 5120x7138 5120x7138+0+0 1-bit Bilevel Gray 4.35672MiB 0.610u 0:00.487
scan.pnm=> GROUP4 5120x7138 5120x7138+0+0 1-bit Gray 124981B 284.590u 4:43.594
scan.pnm=> GROUP4 5120x7138=>76x106 76x106+0+0 1-bit Gray 242B 0.150u 0:00.134
scan.pnm=>scan.pdf PBM 5120x7138 5120x7138+0+0 1-bit Bilevel Gray 127042B 285.280u 4:44.267

real	4m44.795s
user	2m5.962s
sys	2m39.970s


Input image here: https://stephan.walter.name/files/scan.pnm

I tried to reproduce the issue with upstream
https://github.com/ImageMagick/ImageMagick6 , but the PDF file generated
was just noise - I'm probably missing some `configure` options or
libraries.

** Affects: imagemagick (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: imagemagick (Ubuntu Jammy)
     Importance: Undecided
         Status: New

** Affects: imagemagick (Ubuntu Kinetic)
     Importance: Undecided
         Status: New

-- 
Fax/PDF performance regression compared to focal
https://bugs.launchpad.net/bugs/1992228
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