I just wanted to post here a little bit on what has been in the works for our Image Processing framework for Xojo.
Basically in the coming versions of PictureEffectsRaw we will start to add asynchronous methods to every single class. This will probably happen gradually, adding few effect classes per release.
So here is what this means for your code: (Time line on left showing old style synchronous mode, time line in the middle showing asynchronous mode with complete hook and time line on right showing asynchronous mode without complete hook)
All three modes will be supported.