A comparison of what is available in these different packages is underway. MR offers the very best in algorithms, and is used with other display environments. Publicly available systems include ImageMagick and xv. For FITS images, SAOimage is an excellent package, and FView and others are available for Windows. It is also very easy to use MR in conjunction with IDL, with the latter serving as display environment.
FITS extensions entail multiple frames.
The first frame only is read and processed. Of course breaking the multiple frame FITS file into single frames allows MR to be used straightforwardly on any one.