Menu

Gamma correction

Michal J.
2023-05-14
7 days ago
  • Michal J.

    Michal J. - 2023-05-14

    Hi. I have such an hot request. Would it be possible to create the possibility of modifying the image in terms of gamma correction? In the "Image" section, there is already a "Brightness/Contrast" correction, but "Gamma" would give the possibility of correction, which is hard to do by adjusting the brightness and contrast ... Many thanks in advance :)
    Michael

     
  • Champs

    Champs - 7 days ago

    Bumping this post. My scanner is unsupported in recent MacOS versions but Xsane on arm64 Ubuntu VM seems to do gamma correction

     
  • Ben Olden-Cooligan

    There's no manual gamma option, but you could try "Document Correction" under the "Image" menu, which does an automatic adjustment.

     
  • Champs

    Champs - 7 days ago

    Most frequently, I scan receipts, which have notoriously variable ink density.

    The page on the left is untouched, the page on the right is a rescan. I selected that preview, then ran Image > Document Correction. Unless I'm misunderstanding the feature, Document Correction makes no visible difference to the naked eye.

     
    • Ben Olden-Cooligan

      Oh yeah that's not a color balance issue that can be corrected with post-processing (Document Correction helps when things are grey instead of proper white/black). It's a scan issue, and NAPS2 doesn't yet allow custom SANE options which presumably help here.

       
    • Ben Olden-Cooligan

      You could try scanning "Grayscale" instead of "Black and White" (then follow it up with "Document Correction").

       
  • Champs

    Champs - 7 days ago

    Grayscale is the key. Pure B&W would be ideal but this will do.

    For posterity, I've attached the workflow other visitors might be familiar with and expecting.

     

Log in to post a comment.