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V4.27 - Images rotate 180 degrees, not 270 degrees

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    Reported V4.27 - Images rotate 180 degrees, not 270 degrees

    Operating System: Windows XP Pro, SP3
    IrfanView version number: 4.27
    Hardware specification:
    Dell XPS 630
    Intel Core2 Quad CPU
    Q9450 @ 2.66gHz 3.25 GB of RAM

    Steps to reproduce bug:

    Start the Thumbnail window.

    When in Thumbnail view, from the menu bar
    - select File > JPG Lossless Operations > Lossless Rotation with selected files
    - select Rotate clockwise: 270 degrees
    - place checkmarks in the checkboxes for "Optimize JPG file" and "Apply original EXIF date/time to new file"
    - select "Keep all APP markers"
    - click the Start button

    The resulting rotation is 180 degrees, not 270 degrees

    #2
    Always uncheck the Auto rotate image according to EXIF info option in Properties >JPG/PCD/GIF before doing a JPG lossless rotation.
    Otherwise you are permanently rotating an image that has already been temporarily rotated for you to view. Guaranteed to confuse.

    Comment


      #3
      Originally posted by Mij View Post
      Otherwise you are permanently rotating an image that has already been temporarily rotated for you to view. Guaranteed to confuse.
      That was exactly the problem -- and, yes, very confusing.

      But there still seems a programmatic issue: How will I know which photos have incorrect EXIF orientation tags if I turn off the 'auto rotate to EXIF info'? Looks as though I'll have to copy the incorrectly rotated photos to a directory, turn off auto rotate, then fix the photos and copy them back to the original directory. A bit cludgy.

      It seems that IrfanView should be able to read the 'auto rotate' factor, then compensate for that in the rotation operation.

      Thanks for explaining the problem and how to fix it.

      Cheers,

      Charax

      Comment


        #4
        Yes what you have to realize is that Auto-rotate is a Viewing function. It rotates the image according to the Exif tag so that, assuming the tag is correct, the image can be Viewed the right way up. The file containing the image is not changed in any way unless you do some manual editing and then save it.

        JPEG lossless rotation is an Editing function. It rotates the image by the angle you have requested and automatically saves it like that. It changes the Exif tag to Top left to ensure that it is no longer rotated by the Auto-rotate viewing function in future. The issue we are discussing arises because unlike many programs Irfanview tries to be both a universal Viewer and an Editor at the same time.

        There is no issue if you apply the Jpeg lossless Auto rotate (according to Exif orientation) editing function to all images. In this case the Auto-rotate Viewing function accurately previews what the Jpeg lossless Auto-rotate editing function will do to the files. If any of the Exif tags were incorrect then the images can now be individually rotated by the necessary amount using the specific Jpeg lossless function. Because the operations are lossless you do not get any cumulative degradation of the images by doing it in 2 stages.

        Comment


          #5
          transpose please

          I'm here because I got confused during some rotation operations and thought it might be a bug. With XP and IV4.25(autorotate checked) and EXIF-tagged jpgs from a Sony alpha200 I see thumbnails in windows without corrected orientation, thumbnails in IV the same, IV preview corrected and then unpredictable results of rotation. Couldn't find help on "Reset EXIF orientation tag". The tidiest solution for me would be a lossless operation that transposes the jpg according to the EXIF orientation and then strips out the EXIF orientation so that operating system thumbnails and everything downstream would show the picture correctly. Anyone agree?

          Comment

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