CMYK JPEGs showing up as inverted?

Discussion in 'Mac Basics and Help' started by Makosuke, Feb 19, 2013.

  1. macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #1
    I was looking at this article about some classic Apple fantasy designs (which already made the rounds a few weeks ago), but for some reason the image gallery was showing up as inverted in Safari (10.6 version) for me.

    I tried extracting and saving one of the JPEGs from it, and it's a CMYK image. If I open it in Preview (again, in 10.6) it also shows inverted. Opened in Firefox or Chrome, however, and it's normal. Same for Photoshop--normal.

    Is this an OS-level bug, or is something wonky with my system? And do ALL CMYK JPEGs do this, or is it something weird with the ones in this article? (Obviously they're fine for most people, since the comments are the expected Google/Apple fanboy bickering, with no comments about the images.)
     
  2. macrumors 601

    Mr. Retrofire

    Joined:
    Mar 2, 2010
    Location:
    www.emiliana.cl
    #2
    This is a OS X level bug. Probably in the Core Graphics or Image IO frameworks. Report the bug here:
    http://www.apple.com/feedback/macosx.html

    Thanks!

    Btw, i see the same bug here (Mac OS X 10.6.8/Safari 5.1.7).
     
  3. macrumors newbie

    Joined:
    Jul 22, 2012
    #3
    Not a bug!

    I ran into this myself when looking at some .cbr files (compressed comics)

    This isn't a bug per se... the images most likely don't have a color profile defined in the header. This has been true in OSX as far back as 10.4


    http://support.apple.com/kb/TS1252
     
  4. macrumors 601

    Mr. Retrofire

    Joined:
    Mar 2, 2010
    Location:
    www.emiliana.cl
    #4
    Images without color profiles are perfectly normal. You should find another excuse! And as you know, third party applications (Photoshop, for example) do not have this problem.
     
  5. thread starter macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #5
    A follow-up note, having tested, the issue is fixed in 10.8.

    My guess is it was fixed in 10.7, but I no longer have an install of it to test with.

    And honestly, it is a bug in the practical sense. I'm not familiar enough with the JPEG spec to know exactly what interpretation of it results in older versions of Apple's renderer interpreting CMYK JPEGs with no explicit color profile as inverted. It's possible that it's not technically incorrect in the strictest sense, but given that the most major producer of JPEGs (Photoshop) doesn't generate files expecting that behavior, and all major JPEG renderers in use that I'm aware of (Photoshop, Graphic Converter, whatever engines Firefox and Chrome use) don't display them expecting that behavior, it's pretty clear that "standard practice" dictates that QT was doing it wrong.

    Validated, of course, by the fact that they changed/fixed the behavior in the current OS. In some situations, "standard" equals "correct" if the spec isn't specific enough.
     

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