Broken grayscale scanning

[itsmevjnk]

I'm using AirSane with my Canon MF221d, and it seems that it can do color scanning well but not grayscale. When I tried scanning in grayscale using AirSane's built-in eSCL frontend or other 3rd party software (such as Mopria Scan or VueScan) it would just generate 0-byte/corrupted files. Interestingly, this line can also be seen in the service status log:

May 24 10:22:46 hydra airsaned[5638]: /home/itsmevjnk/AirSane/server/scanjob.cpp, line 656: encoder bytesPerLine (2480) differs from SANE bytes_per_line (7440)
May 24 10:22:47 hydra airsaned[5638]: JpegEncoder: bit depth unsupported, aborting

To make sure that the driver isn't the culprit, I've also tried running scanimage in grayscale mode, and it still gives me proper TIFF file. Have I configured something incorrectly, or is this an actual bug?

[SimulPiscator]

Looks like a bug, but I cannot reproduce it. Can you run AirSane in debug mode (see README.md for details), and post the full output? Thanks!

[itsmevjnk]

Here's the debug log: airscan.txt For reference, lines 32-70 are generated during a (failed) grayscale scan, and lines 78-116 are generated during a color scan. Anyways, a workaround that I've found is to enable synthesize-gray, but considering that the synthesized gray may not exactly match the actual shade, I think this bug should be resolved.

[SimulPiscator]

It seems that your backend resets the Color option when setting the Source option. I've reordered setting those options to make such interference less likely. Could you try the latest git version and report whether it works for you now? Thanks!

[itsmevjnk]

It works flawlessly now. Thanks for the speedy fix!

[SimulPiscator]

Thanks for the report.