Last Februrary, I volunteered to help with the GIMP MMX implemetation that had been languishing and had recently started to cause problems when building the current GIMP code.

This (http://oak.mysterious.org/~helvetix/practicum/gimp-composite.tgz) is release 0.0 of an extensible and customisable image compositing interface for the GIMP. This doesn't really provide any 'user visible' changes, other than the potential (and actual in this case) performance improvements.

I'd like to hear feedback.

What you get is this:

* A general mechanism for incorporating compositing functions based upon the compositing function and the pixel formats of the inputs and the outputs of the function.

* Generic implementations of the supported compositing functions as a foundation for further/future improvements.

* The general mechanism allows any compositing function implementation to be replaced by a different implementation. This is particularly useful in that one can write specialised implementation of some, many, or all of the compositing functions. These specialised implementations can be written to take advantage of special CPU instructions, such as VIS, AltiVec, MMX, and so forth, and special hardware acceleration that might be available.

Currently, I have an incipient set of functions implemented which use the MMX instruction set of the Pentium processor.

Helvetix