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    Requested Lepton JPEG compression support

    Hi all! First time poster here.

    I'm sure this is already being considered, but I will suggest it anyway.

    Dropbox has just announced the open source release of Lepton, a new way to compress JPEG files. In their own words:

    Lepton achieves a 22% savings reduction for existing JPEG images, by predicting coefficients in JPEG blocks and feeding those predictions as context into an arithmetic coder. Lepton preserves the original file bit-for-bit perfectly. It compresses JPEG files at a rate of 5 megabytes per second and decodes them back to the original bits at 15 megabytes per second, securely, deterministically, and in under 24 megabytes of memory.

    We have used Lepton to encode 16 billion images saved to Dropbox, and are rapidly recoding our older images. Lepton has already saved Dropbox multiple petabytes of space.

    Community participation and improvement to this new compression algorithm is welcome and encouraged!
    Github release

    Dropbox Lepton announcement

    It goes without saying that this would make a great addition to IrfanView. Saving gigabytes of data for everyone while keeping data integrity is a huge step forward, if this method is as golden as they say it is.

    Last but not least, thank you Irfan Skiljan for your amazing software. It's made picture viewing very pleasant over the years
    Last edited by LuisB; 16.07.2016, 09:41 AM.

    #2
    I would not assume that Irfan Skiljan is considering it. He may not even know about it.

    This is a users forum — he does not visit here as far as I know.

    Welcome to the forum. Please fill in your forum profile.
    Last edited by Bhikkhu Pesala; 19.07.2016, 09:51 AM.
    Before you post ... Edit your profile • IrfanView 4.62 • Windows 10 Home 19045.2486

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      #3
      JPEG+Lepton vs WebP vs Jpeg2000 vs BPG

      Original: 2000x3000 (6.00 MPixels) 19602KB [PNG-lossless]

      Save as - JPEG, progressive, quality 60, subsampling 2x2(4:2:0) - 488KB
      Lepton - 388KB (compress 20.5%)

      And picked closest to the compressed size in the lepton.
      With forced subsampling 2x2 (4:2:0) in all formats.

      WebP - 386KB (cwebp 0.5.1)
      Jpeg2000 - 382KB (OpenJPEG 2.1.1)
      BPG - 398KB (0.9.6, x265)

      Original: http://i023.radikal.ru/1607/6f/f2778e49dea4.png
      Jpeg+Lepton http://s002.radikal.ru/i198/1607/7d/5607596e5734.png
      WebP http://s013.radikal.ru/i324/1607/7f/d0e72e4269d9.png
      Jpeg2000 http://s008.radikal.ru/i303/1607/3e/b1c969879ae4.png
      BPG http://s017.radikal.ru/i427/1607/23/178a23eb312d.png

      Full-Size: https://cloud.mail.ru/public/KxdX/6wSPKH9HW

      Result: JPEG+Lepton has one of the best value for the size/quality, and high speed coding & decoding .
      Last edited by zubzero; 19.07.2016, 07:15 PM.

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        #4
        questions - something I think about to discuss

        Then the big questions here is:
        • Is the source code easilly avaiable?
        • Is there any programs that can encode/recode jpg+Lepton locally on a Windows computer?
        • Have anybody tried to compare size of a JPG file that has being loseless transformed, no rotation + progressive?


        The last point I think is interresting because by applying the jpg loseless transformations + progressive does free up some space. How much will there be possible to gain?
        If it hurts not to drint, don't waste the bottle then.

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          #5
          Sprintdriver,
          Lepton is a tool and file format for losslessly compressing JPEGs by an average of 22%. - dropbox/lepton

          Win-binaries build now SSE4.1 CPU
          Last edited by zubzero; 21.07.2016, 02:14 PM.

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            #6
            I suspect I have missing something here. Does Lepton compression produce a JPG file that is smaller, or does it create an image (or file container) that is not actually a JPG file?
            Last edited by Bhikkhu Pesala; 22.07.2016, 05:50 AM. Reason: Corrected typo
            If it hurts not to drint, don't waste the bottle then.

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              #7
              Lepton is a new image type. You can convert .jpg files to .lep files retaining *all* the data (EXIF), pixels and colours. Converting back to .jpg gives the exact same binary file.
              I converted a 71 GB folder of jpegs into a 58 GB folder of lepton files using the free WinLep program. (Note: It did take a long time!)

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