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Lossless Rotation Of 2272x1704 Images...Query!

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    Lossless Rotation Of 2272x1704 Images...Query!

    Hi All

    I've come accross Irfranview's Lossless Rotation feature and have rotated a few photos with it to great delight as the file size was close to the original unlike in Windows XP Picture Viewer were it would lose 0.1mb or something.

    Anywho I also have some other photos taken by my previous 4 megapixel Canon IXUS 430 camera. These 4 megapixel photos have the dimension of 2272x1074. Now 2272 is divisible by 16 but 1074 is not. Well it is divisible by 16 but it results in 106.5 so its not a full integer.

    Anywho i rotated a file with the Lossless Rotation Plugin and it worked automatically. No prompt came up nor was the resulting image cropped by 8 pixels to get within a multiple of 16.

    So i'm wondering, was that a loseless rotation (Since it is a multiple of 8 although not 16). Or did it rotate with some loss although a prompt didn't come up???

    Additonally could someone tell me what the Optimize JPEG option is for? If u want to do a loseless rotation why would you optimize the JPEG?

    Thanks for your help! Much appreciated!
    Cheers

    #2
    This thread discusses these concerns:

    Reorient Image Using JPG Lossless Operation

    Here is some info on optimization:

    Optimize

    Comment


      #3
      Hi....

      So from reading that link about Optimisation, what i understand is that the process is lossless and image quality isn't affected although the resulting file size is smaller. It's just that with optimisation, different encoding parameters are used but the resulting files are the same if optimisation was turn off?

      Is that a correct understanding???

      How do you tell if a photo uses subsampling??? So from that thread you pointed me to, i can rotate loseless 16 px multiple photos with subsampling and 8 px photos without subsampling?

      Cheers

      Comment


        #4
        Bump...How do i find out if my photo has sub sampling?

        Thanks heaps!

        Comment


          #5
          What is an Optimized JPEG?
          JPEG Minimum Coded Unit (MCU) and Partial MCU

          Comment


            #6
            Originally posted by Benmc View Post
            How do i find out if my photo has sub sampling?
            Try ExifToolGUI:

            Click image for larger version

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