Some CLI operations take single frames only.

[bluescan]

Almost all (all?) CLI operations should be able to specify the frame(s). In some cases it is not an option at all. In other cases (brightness, levels, contrast) you can specify a single frame or all frames. For some operations an interval set may be specified (this is the most generic/powerful).

All operations should allow interval frame sets to be specified... perhaps in a generic way outside of the operation or post operation... but if done like that, then there's no ability to pipeline operations that work on different frames.... so maybe just all ops and post ops allow a shared and consistent parsing of a 'frames' argument.