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Thread: JPG_TRANSFORM "Perfect tranform only" not working with "Auto-rotate"

  1. #1

    Default JPG_TRANSFORM "Perfect tranform only" not working with "Auto-rotate"

    Steps to repeat.

    1. Take a JPEG picture with an EXIF orientation tag. In my case, the file was created by an Android phone held portrait, and downloaded via Google Photos.

    My image is 1836 x 3264, as reported in IrfanView or other EXIF-aware software such as Windows Explorer in Win10. The raw dimensions are 3264 x 1836, as reported by non-EXIF software functions such as PHP getimagesize() or Perl Image::Size:imgsize().

    Note 1836 is not divisible by 16.

    2. Verify in IrfanView: Image / Information / EXIF info / Orientation: "Right top".
    Note, the default Orientation is "Top left".

    3. Make a copy to work with and open it in IrfanView.
    Options / JPG Lossless Transformation.
    Check: Auto-rotate (according to EXIF orientation, if available).
    Check: "Perfect" transformations only (don't cut OFF rows/columns in this case).
    Click Start.

    The image is 1824 x 3264, raw and as reported by EXIF-aware software.
    The EXIF Orientation is default, "Top left."

    IrfanView refuses to cut pixels. 'JPG Transformation error: "Perfect" operation is not possible. Bad image dimensions.'

    To get the expected result, change step 3 to:
    Check: Rotate clockwise: 90 degrees
    Check: "Perfect" transformations only (don't cut OFF rows/columns in this case)

  2. #2


    Tested with IrfanView 4.52 on Win10, in both 32-bit and 64-bit, with all plugins installed.

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