QuickTime 4 Reference

Specifying the Bit Depth for Paths

QuickTime allows you specify the minimum bit depth for drawing all paths in a vector data stream. If the bit depth of the display device is less than the bit depth specified by the kCurveMinimumDepthAtom atom, the path is rendered into an offscreen buffer with the minimum bit depth and then transferred to the screen. This value must be at least 16 for most transfer modes. If the quality of a dithered image is unsatisfactory, increasing the kCurveMinimumDepthAtom value to 32 may improve the result.

A kCurveMinimumDepthAtom atom is optional. By default, the bit depth of the output is not changed. There can be at most one kCurveMinimumDepthAtom atom in a vector data stream, and if included it must be the first atom in the stream.

You may also specify kCurveDepthAlwaysOffscreenMask to force rendering offscreen of complex curves.