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#81 JPG lossless mode not lossless!

15.x
closed
Nikkho
None
2022-03-04
2020-08-01
necros
No

in Best Lossless mode jhead changes jpg resolution and decrease colors

Discussion

  • necros

    necros - 2020-08-01

    actually decrease colors

     
  • Devedse

    Devedse - 2020-08-02

    Hi Necros, I've noticed this issue happens for some images that are rotated using the exif rotate flag. If you first unrotate the image, then optimize it and then rerotate it, it should remain lossless.

    I've build this functionality in my own tool that makes use of FileOptimizer: https://github.com/devedse/DeveImageOptimizerWPF

     
  • necros

    necros - 2020-08-03

    OK, thanx for info

     
  • Devedse

    Devedse - 2022-03-04

    @Nikkho, are you still interested in fixing this issue? It can be done by removing the exif rotation flag before optimization and reapplying it after.

     
  • Nikkho

    Nikkho - 2022-03-04

    Unfortunately I am not able to reproduce the issue. Optimized sample.png and colors in original and optimized verions where the same.

    Original.

     
  • Nikkho

    Nikkho - 2022-03-04

    Optimized

     
  • Devedse

    Devedse - 2022-03-04

    So previously this issue happened with for example the Image I've attached. I did just retest this and apparently it doesn't happen anymore. So this issue can be closed :).

     
  • Nikkho

    Nikkho - 2022-03-04
    • status: open --> closed
    • assigned_to: Nikkho
    • Milestone: 14.x --> 15.x
     

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