What's New in QuickTime 5
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QuickTime has defined new APIs to handle gamma processing when compressing or decompressing to and from PixMaps using certain codecs.
The Macintosh has defined the standard gamma response of PixMaps as 1.8, while Windows display cards typically have a gamma response of 2.5 for bitmaps. In contrast, standard television based video has a gamma response of 2.2. For further details, refer to <http://www.inforamp.net/~poynton/GammaFAQ.html> .
By default, codecs such as the Apple DV codec convert from gamma 2.2 to 1.8 when decompressing from DV to RGB in order to maintain the apparent gamma of the image when displayed on the Mac display or for processing in Mac RGB space. Similarly, the reverse conversion is done when compressing from RGB to DV.
However, linear processing of effects in Mac-RGB with gamma 1.8 does not create a linear effect when viewed again on a video display at gamma 2.2. To allow for this, the following APIs are designed so that applications can control the gamma conversion during compression and decompression for processing such as rendering video effects.
What's New in QuickTime 5
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