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Managing Color With ColorSync


Multiprocessor Support

Starting with version 2.5, ColorSync's default CMM can take advantage of multiple processors. Multiprocessor support is transparent to your code--the CMM invokes it automatically if the required conditions are met.

When ColorSync Uses Multiple Processors

The default CMM takes advantage of multiprocessor support only if the following conditions are satisfied:

  1. The MPLibrary was successfully loaded at boot time.
  2. The CMM successfully links against the MPLibrary at runtime.
  3. The number of processors available is greater than one.
  4. The number of rows in the image is greater than the number of processors.
  5. The source and destination buffers have the same number of bytes per row or have different locations in memory.

Unless all of these conditions are met, matching will proceed without acceleration. Multiprocessor support is currently supplied only for the following component request codes:

As a result, the default CMM invokes multiprocessor support only in response to the general purpose CWMatchPixMap and CWMatchBitmap functions, or when those calls are invoked as a result of a call to the QuickDraw-specific matching routines, such as NCMBeginMatching.

Efficiency of ColorSync's Multiprocessor Support

Depending on the image and other factors, ColorSync's matching algorithms take advantage of multiple processors with up to 95% efficiency (your mileage may vary). If you have two processors, for example, ColorSync can complete a matching operation in as little 53% of the time required by one processor. Additional processors should provide proportional improvement.


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