Comment 6 for bug 1888238

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!