Solar physicists are often interested in only a subfield of the Sun. Since the Sun rotates, features can move across the disc of the Sun. It would be good to have a feature tracking capability on HV/JHV. Perhaps it work like this - the user picks a point on the disc. As the user steps forward and backwards in time, that point remains in the same location relative to the viewer window. The Sun will appear to rotate underneath that point (which is a feature the user is interested in). HV will have to work out which tiles will have to returned in order to keep the selected feature at the same location in the user window. JHV will have to work out which parts (wavelet coefficients of the sub-region) of the JPEG2000 files will have to returned in order to keep the selected feature at the same location in the user window. Thanks!
Now that hv.org has movie capability I have changed the criticality of this feature request.