rotating JPG's, Windows explorer context menu, ImageMagick, anyone?

Discussion in 'Digital Photography' started by Robert Barr, Dec 7, 2004.

  1. Robert Barr

    Robert Barr Guest

    Try hunting down a utility called "cPicture". I'm pretty sure it's
    freeware, and it states that its rotation function is lossless. I don't
    know about automating the process.

    (I've used it and I don't doubt that it's lossless, but of course I'm
    not enough of an expert to say with certainty.)
     
    Robert Barr, Dec 7, 2004
    #1
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  2. Robert Barr

    Todd H. Guest

    Howdy,

    Windows XP has a context menu Rotate Left and Rotate Right commands in
    the Explorer context menu for jpeg's (the context menu is the you see
    when you right click on a JPG file in Windows explorer).

    That's mighty darned handy. Unfortunately, Microsoft's version of
    that in XP results in smaller files as well as a noticeable loss in
    image quality in the process, likely due to using a default low JPEG
    quality factor in the conversion, and further unfortunately, it does
    me no good in Windows 2000.

    What I'd like to do is create my own Context menu entries RotateLeft
    and RotateRight for the JPG file type, leveraging the ImageMagick
    command line program convert, in this way:

    convert -rotate 90 -quality 95 %1 %1_rot.JPG

    Unfortunately, I'm running into some issues debugging the entry I've
    made in Explorer's Tools>Folder Options>File Types>JPG>Advanced New
    actions dialog box despite having added the appropriate cygwin
    directories to my path.

    I thought I'd throw the question out with the confidence that some has
    had to have done this before.... It seems to do it right, a batch
    file will be involved, and will need some fancier batch file
    constructs than I've used in the past.

    Anyone invented this wheel already? Googling has yielded no fruit for
    me thus far, and I'd appreciate any help to get me into the endzone on
    this one! :-\

    Best Regards,
     
    Todd H., Dec 7, 2004
    #2
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  3. Robert Barr

    cyclone Guest

    This thread indicated xp jpg rotation was lossless with some evidence to
    back it up. Some talk of it only being lossless for resolutions that are
    multiples of 16 though.

    http://groups-beta.google.com/group/rec.photo.digital/browse_thread/thread/8
    4fcba5d56fea8c7?hl=en&rnum=1

    Tony
     
    cyclone, Dec 8, 2004
    #3
  4. Robert Barr

    Todd H. Guest

    Thanks for the interesting link. I strongly question its assertion of
    lossless compression, however because I can generate counter
    datapoints at will on my XP home machine, it seems.

    Trying to figure out then why images from my digital rebel (which is
    x16 in X and Y of all resolutions) go, for example from 1.52MB
    filesize to 1.18Mb for a 2048 x 1360 image.

    I'm no information theory expert, but Windows XP's rotate function is
    certainly tossing away something there, and I don't think there's
    300MB of metadata that can explain the file size reduction.

    Best Regards,
     
    Todd H., Dec 8, 2004
    #4
  5. Robert Barr

    Robert Lynch Guest

    This won't help you add a context menu, but you might want to consider the
    latest beta of BetterJPEG (http://www.betterjpeg.com/). I am currently
    evaluating
    it and it seems to be a good tool for lossless rotation and cropping.

    You also might something of value in one of the programs listed here:

    http://sylvana.net/jpegcrop/losslessapps.html

    All of these programs incorporate lossless JPEG transforms.
     
    Robert Lynch, Dec 8, 2004
    #5
  6. It's easy enough to check whether something was really lost: Take an
    original, make a copy of it, then rotate the copy. Read both into
    Photoshop or other editor. Rotate the copy image back to its original
    orientation. Calculate the difference between the two images (Photoshop
    has a difference operator; other editors probably have something
    similar).

    The rotation in Photoshop is lossless because it's done on a fully
    expanded image. If XP's rotation was lossless too, then the two images
    should match exactly.

    Dave
     
    Dave Martindale, Dec 8, 2004
    #6
  7. Keith Sheppard, Dec 8, 2004
    #7
  8. Guido Vollbeding, Dec 8, 2004
    #8
  9. Robert Barr

    E. Magnuson Guest

    E. Magnuson, Dec 9, 2004
    #9
  10. Robert Barr

    Todd H. Guest

    My god--that's perverse. But that'd sure as heck explain it. Thanks
    for the great links and education on XP's rotation.

    Still looking for any Windows savvy hackers who can answer the
    original question to provide similar functionality for Win2K.

    Best Regards,
     
    Todd H., Dec 10, 2004
    #10
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