NSBitmapImageRep and colour spaces

  • I am having problems understanding how NSBitmapImageReps and different
    colour spaces interact. In particular, what is the difference between
    passing, say, NSCalibratedRGBColorSpace and NSDeviceRGBColorSpace as
    the colorSpaceName: parameter to [NSBitmapImageRep
    initWithBitmapDataPlanes: ...] ?

    I can understand device RGB, but in the calibrated case, _which_
    calibrated RGB colour space is this? (For the record, I tried both and
    I'm not seeing any obvious differences when wrapping the resulting
    bitmap in an NSImage and drawing it to an NSView).

      -- Ture
  • On Dec 14, 2007, at 3:25 PM, Ture Pålsson wrote:

    > I am having problems understanding how NSBitmapImageReps and different
    > colour spaces interact. In particular, what is the difference between
    > passing, say, NSCalibratedRGBColorSpace and NSDeviceRGBColorSpace as
    > the colorSpaceName: parameter to [NSBitmapImageRep
    > initWithBitmapDataPlanes: ...] ?

    Calibrated color spaces use ColorSync to calibrate the colors; device
    color spaces don't. Generally, you should only use calibrated color
    spaces if color preservation across devices is important.

    Nick Zitzmann
    <http://www.chronosnet.com/>
  • On Dec 15, 2007 12:17 AM, Nick Zitzmann <nick...> wrote:
    >
    > On Dec 14, 2007, at 3:25 PM, Ture Pålsson wrote:
    >
    >> I am having problems understanding how NSBitmapImageReps and different
    >> colour spaces interact. In particular, what is the difference between
    >> passing, say, NSCalibratedRGBColorSpace and NSDeviceRGBColorSpace as
    >> the colorSpaceName: parameter to [NSBitmapImageRep
    >> initWithBitmapDataPlanes: ...] ?
    >
    >
    > Calibrated color spaces use ColorSync to calibrate the colors; device
    > color spaces don't. Generally, you should only use calibrated color
    > spaces if color preservation across devices is important.

    Yes, that much is pretty obvious, but how?

    If I pass NSCalibratedRGBColorSpace, _which_ calibrated colour space
    is assumed? sRGB? Adobe RGB? SomeFancyAppleRGB? And how does this
    interact with the NSImageColorSyncProfileData property?

      -- T
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