Following up: I published an update to this tool that helps make "bad" rips 
more square.  ImageDisk will create an IMD file that faithfully lacks sectors 
that it can find no trace of.  So reading marginal media that has unreadable 
and unlocatable sectors will have a track that is perhaps shorter than tracks 
that came before it because it's lacking unfindable sectors.  Worse than that, 
IMD will decide that's the new norm and stop looking for that sector on later 
tracks as well (unless you have it analyze every sector which is slow, but at 
least it improves fidelity in reading marginal media). That's a different 
problem.  For cases where you're missing a sector here or there and the rest of 
the sectors are fine within tracks, this new option to fill in missing sectors 
will help.

Recall that the function of IMDU and this tool (imd2raw) is to take a rich IMD 
image and linearize it into a raw image.  That image really needs to be square 
in order to have it make any sense because there's no metadata anywhere to 
explain where or why a sector might be missing.  So the only reasonable thing 
to do in this situation is to pad out the missing sector with zeros or xE5s so 
that subsequent tracks and sectors can be located reliably with consistent 
offsets.  The default behavior is still to be exactly like IMDU was, but the 
optional –f or --fill-missing parameter will make this change for the output 
image and indicate missing sectors with a '0' in the graphical display.

https://github.com/RetroFloppy/imd2raw

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