Further investigation of my backups shows that I never had a "jpeg-quality" 
setting in GNOME settings on this machine before 
("HOME=/path/to/restored/homedir dconf dump /org/gnome/simple-scan/").
I do have jpeg-quality=75 on the old machine that was connected to the scanner 
until 5 years ago...

So it looks like there is a problem with the default value if the "jpeg-
quality" setting does not exist (i.e. has never been changed and
saved?).

src/app-window.vala:  quality_adjustment.value = settings.get_int
("jpeg-quality");

However, data/org.gnome.SimpleScan.gschema.xml does show a suitable
default:

    <key name="jpeg-quality" type="i">
      <range min="0" max="100"/>
      <default>75</default>
      <summary>Quality value to use for JPEG compression</summary>
      <description>Quality value to use for JPEG compression.</description>
    </key>

-- 
You received this bug notification because you are a member of Desktop
Packages, which is subscribed to simple-scan in Ubuntu.
https://bugs.launchpad.net/bugs/2024887

Title:
  Bad image quality when saving JPEG or PDF scans

Status in simple-scan package in Ubuntu:
  New

Bug description:
  Description:  Ubuntu 22.04.2 LTS
  Release:      22.04
  simple-scan:
    Installed: 42.0-1
    Candidate: 42.0-1
    Version table:
   *** 42.0-1 500
          500 http://be.archive.ubuntu.com/ubuntu jammy/main amd64 Packages
          100 /var/lib/dpkg/status

  When saving a document scanned using "Image" settings to JPEG or PDF format, 
the resulting quality is really bad.
  The image shown in the scan window looks fine, so this is not a scanner issue.
  When saving to (lossless) PNG, the quality is also fine.

  This is also reflected in the file sizes, e.g. for a 600 dpi scan of a 19x13 
cm photo:
    - PNG: 12575069 bytes (OK)
    - JPEG: 227595 bytes (BAD)
    - PDF: 229414 bytes (BAD)
  It looks like the compression rate for (embedded) JPEG files is way too large.

  When scanning using "Text" settings, the resulting quality is fine (I
  rescanned an old document and compared the results). The difference
  with a scan using the "Image" settings is very clear, even for text
  documents.

  Version 3.36.3-0ubuntu0.20.04.0 did not have this problem.
  I downloaded and installed 42.5-1 from kinetic, but that did not fix the 
issue.

  Thanks!

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