Hi Martin,
thank you for sharing your exxperience.  Seems you had a more difficult time than Swissz, but found a solution.
I will test on a non prodduction 20.04 and see how it goes.
Regards

    On Thursday, January 6, 2022, 08:16:01 AM CST, Martin Sorgatz <email address hidden> wrote:  
 
 I have an old computer with Ubuntu 18.04 LTS where simple scan works fine with an HP Envy printer/scanner.
Now I got a new computer and installed 20.04 LTS where the simple scan shows this issue with the same scanner.

The downgrade of libsane-genesys.so from 1.0.29 to 1.0.27 (I took it from the old computer) does not help on 20.04.
Maybe there are some more bugs in libsane that are already fixed in Ubuntu 21.04?
So I copied the complete /usr/lib/x86_64-linux-gnu/sane/ directory from 18.04. to the 20.04 installation as "sane-old", including the libsane.so.1.0.27 from the directory level above.
I created a shell script that starts simple-scan with LD_LIBRARY_PATH=/usr/lib/x86_64-linux-gnu/sane-old.
But it did not work. I checked the process which libs are loaded (using sudo pldd <pid>).
It loaded mostly the libs from sane-old, but there were still two of the original libs:
.../sane/libsane-ricoh2.so.1
.../sane/libsane-escl.so.1

Then (in /usr/lib/x86_64-linux-gnu) I renamed the "sane" directory to "sane-hidden".
Now (without LD_LIBRARY_PATH) no more original lib from the original subdirectory is used any more (except the top level libsane.so.1 from 1.0.29).
=> Now brightness and contrast can be applied as expected!

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You received this bug notification because you are subscribed to the bug
report.
https://bugs.launchpad.net/bugs/1888238

Title:
  Ubuntu 20.04 simple-scan brightness and contrast controls have no
  effect

Status in Simple Scan:
  Unknown
Status in simple-scan package in Ubuntu:
  Incomplete

Bug description:
  Ubuntu 20.04 simple-scan.  The Brightness and Contrast controls have
  no effect.  No matter how I position the sliders the scan image
  remains the same, ie, a dark background.  It is as if the controls are
  not 'connected'.

  Ubuntu 20.04 is up to date.  The scanner is a Cannon LiDE60.

  I have 19.10 in another partition. Simple-scan works as expected.
  Ditto for 18.04.

  Regards.

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: simple-scan 3.36.0-0ubuntu1
  ProcVersionSignature: Ubuntu 5.4.0-40.44-generic 5.4.44
  Uname: Linux 5.4.0-40-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.3
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Jul 20 09:47:52 2020
  InstallationDate: Installed on 2020-05-12 (68 days ago)
  InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
  MachineType: Hewlett-Packard HP EliteBook 8570p
  ProcEnviron:
  PATH=(custom, no user)
  XDG_RUNTIME_DIR=<set>
  LANG=en_US.UTF-8
  SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-40-generic root=UUID=dc547d11-1deb-404b-988a-a88d4772e66d ro quiet splash vt.handoff=7
  SimpleScanLog:
  
  SourcePackage: simple-scan
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 12/05/2012
  dmi.bios.vendor: Hewlett-Packard
  dmi.bios.version: 68ICF Ver. F.32
  dmi.board.name: 17A7
  dmi.board.vendor: Hewlett-Packard
  dmi.board.version: KBC Version 42.32
  dmi.chassis.asset.tag: 8022456
  dmi.chassis.type: 10
  dmi.chassis.vendor: Hewlett-Packard
  dmi.modalias: dmi:bvnHewlett-Packard:bvr68ICFVer.F.32:bd12/05/2012:svnHewlett-Packard:pnHPEliteBook8570p:pvrA1029D1102:rvnHewlett-Packard:rn17A7:rvrKBCVersion42.32:cvnHewlett-Packard:ct10:cvr:
  dmi.product.family: 103C_5336AN G=N L=BUS B=HP S=ELI
  dmi.product.name: HP EliteBook 8570p
  dmi.product.sku: D2C13UP#ABA
  dmi.product.version: A1029D1102
  dmi.sys.vendor: Hewlett-Packard

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