Lossless rotation in Irfanview

Discussion in 'Digital Photography' started by Terry Orchard, Nov 11, 2003.

  1. Irfanview has a lossless rotation option that lets you rotate a jpg
    image 90 or 180 degrees, without recompressing the data. On the
    lossless rotation dialog, there is a checkbox for "Optimize Jpg File".
    Does anyone know what that does?

    I ran a test on a file, that was originally 907,010 bytes in size.
    When I did a lossless rotation with this checkbox un-checked, the
    result was 906,430 bytes. When I did a lossless rotation with this
    checkbox checked, the result was 895,116 bytes.

    When I opened the two files and saved them as bmp's, and compared
    them, they were identical, so the "optimize" is not converting
    lossless to lossy. And they both appear to have preserved the EXIF
    data.

    Any clues? TIA,

    Terry
     
    Terry Orchard, Nov 11, 2003
    #1
    1. Advertising

  2. Terry Orchard

    Mike S. Guest

    In article <>,
    Terry Orchard <> wrote:
    >Irfanview has a lossless rotation option that lets you rotate a jpg
    >image 90 or 180 degrees, without recompressing the data. On the
    >lossless rotation dialog, there is a checkbox for "Optimize Jpg File".
    >Does anyone know what that does?


    The code is derived from JPEGTRAN, a utility from the JPEG Group which
    offers an "-optimize" option in the command list. From the original
    description I think it optimizes the structure of the Huffman tables to
    provide more efficient coding and smaller file size. The actual content of
    the bitmap image is not changed.


    From the docs:

    -optimize
    Perform optimization of entropy encoding parameters. Without
    this, default encoding parameters are used. -optimize usually
    makes the JPEG file a little smaller, but at the price of
    slower compression. Note that -progressive implies -optimize.
     
    Mike S., Nov 11, 2003
    #2
    1. Advertising

  3. Mike S. wrote:

    >In article <>,
    >Terry Orchard <> wrote:
    >>Irfanview has a lossless rotation option that lets you rotate a jpg
    >>image 90 or 180 degrees, without recompressing the data. On the
    >>lossless rotation dialog, there is a checkbox for "Optimize Jpg File".
    >>Does anyone know what that does?

    >
    >The code is derived from JPEGTRAN, a utility from the JPEG Group which
    >offers an "-optimize" option in the command list. From the original
    >description I think it optimizes the structure of the Huffman tables to
    >provide more efficient coding and smaller file size. The actual content of
    >the bitmap image is not changed.
    >
    >From the docs:
    >
    > -optimize
    > Perform optimization of entropy encoding parameters. Without
    > this, default encoding parameters are used. -optimize usually
    > makes the JPEG file a little smaller, but at the price of
    > slower compression. Note that -progressive implies -optimize.



    Thanks!
     
    Terry Orchard, Nov 11, 2003
    #3
  4. "Mike S." wrote:
    >
    > In article <>,
    > Terry Orchard <> wrote:
    > >Irfanview has a lossless rotation option that lets you rotate a jpg
    > >image 90 or 180 degrees, without recompressing the data. On the
    > >lossless rotation dialog, there is a checkbox for "Optimize Jpg File".
    > >Does anyone know what that does?

    >
    > The code is derived from JPEGTRAN, a utility from the JPEG Group which
    > offers an "-optimize" option in the command list. From the original
    > description I think it optimizes the structure of the Huffman tables to
    > provide more efficient coding and smaller file size. The actual content of
    > the bitmap image is not changed.
    >
    > From the docs:
    >
    > -optimize
    > Perform optimization of entropy encoding parameters. Without
    > this, default encoding parameters are used. -optimize usually
    > makes the JPEG file a little smaller, but at the price of
    > slower compression. Note that -progressive implies -optimize.


    See also http://jpegclub.org/jpegcrop/

    Regards
    Guido
     
    Guido Vollbeding, Nov 12, 2003
    #4
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Rili

    jpg lossless rotation for free with IrfanView

    Rili, Sep 18, 2003, in forum: Digital Photography
    Replies:
    2
    Views:
    2,126
  2. Jim Garrison

    ImageMagick and lossless JPEG rotation?

    Jim Garrison, Sep 30, 2003, in forum: Digital Photography
    Replies:
    8
    Views:
    11,667
    C0mdrData
    Oct 1, 2003
  3. Gary Fritz

    Canon A70 Q's: lossless rotation, JPG quality

    Gary Fritz, Oct 17, 2003, in forum: Digital Photography
    Replies:
    8
    Views:
    2,339
    Gary Fritz
    Oct 20, 2003
  4. Louise

    Why is lossless rotation actually gainful rotation?

    Louise, Jan 28, 2004, in forum: Digital Photography
    Replies:
    19
    Views:
    675
    Guido Vollbeding
    Feb 2, 2004
  5. irfanview lossless jpg rotation

    , Sep 24, 2006, in forum: Digital Photography
    Replies:
    22
    Views:
    1,688
    JC Dill
    Oct 1, 2006
Loading...

Share This Page