Another update to my histogram match script. Now with a whole bunch of channel options - In addition to Value and RGB, there is now HSV, HS, LAB, AB, YCrCb, and CrCb. If the images are real close, like two exposures of the same scene, try RGB. To transfer the colours, try AB (preserve L) or CrCb (preserve Y).
EDIT: One more change to the uploaded file, the script not decides if rescaling is needed and does it automatically to an optimal size.
A few improvements have been made to my histogram match script. The big new features include histogram interpolation, and adjustments for saturation and contrast. Special thanks to Isomage who helped with some of the scheme subroutines.