[sane-devel] Scanjet 7650 (hp5590) cannot access readonly values from command line

[hm]

Hi,

There is an issue with the readonly values from the hp5590 backend and 
the Scanjet 7650.

Listing the options specific to the hp5590, some report the scanner's 
status:

--doc-in-adf
--color-led
--button-pressed
--counter-value

Trying to read these values with the command line gives an error:

$ scanimage --device-name hp5590 --color-led
Output format is not set, using pnm as a default.
scanimage: unrecognized option '--color-led'

They are, however, correctly reported when using -A:

$ scanimage -d hp5590 -A | grep color-led
Output format is not set, using pnm as a default.
     --color-led color|black_white [color] [hardware]

<Pressing the button>

$ scanimage -d hp5590 -A | grep color-led
Output format is not set, using pnm as a default.
     --color-led color|black_white [black_white] [hardware]


On Linux Mint 20.3:
$ scanimage --version
scanimage (sane-backends) 1.0.32; backend version 1.0.29


How do I access these readonly values using scanimage? I know I could 
grep and cut for them, but that's not ideal.

Thanks,