Are you sure the "Note" field will do more good than harm?  

  "(5) Target mis-identifications"

  "Please be aware that some targets have been found to be mis-
  identified in the index files. We have corrected those that have 
  been brought to our attention, but some mis-identifications are 
  likely to remain. Please report any known errors to the PDS Rings 
  Node."

  I've looked at three Uranus images so far (admittedly all from the 
  same sequence), and they all contained the same egregiously wrong 
  information in the Note field of the .LBL file.

  NOTE                            =
  "1 OF 46 FRAMES IMAGING RING STRUCTURE AND SHEPHERD SATELLITES." 

  Noooo.

  2681942, 2681948, and 2681954 are 3 of 6 frames imaging Uranus at 19 
  deg phase angle.  2682000, 2682006, and 2682012 are the other three, 
  and yes, I just checked, their NOTE field is wrong too.

High-pass-filtered Uranus images  

  I've put two Uranus images with the average of an 11x11 surrounding 
  box subtracted from each pixel in the krages/public directory on 
  files.seti.org.  And if you remember how to get to krages/public 
  without first logging in as krages and giving my password, would you 
  please remind me, because I've forgotten.

  The files are boxc2681948.fits and boxc2681954.fits.  That's right. 
  FITS.  For reasons that pass understanding, xv has decided to stop 
  working for real and halfword VICAR images; I have no intention of 
  actually trying to install VICAR; and don't get me started on 
  Nasaview. If I want to create them and then look at them, they have 
  to be .fits.

  The images show the "instrumental" structure that is not removed by 
  the standard calibration.  (They also show a bright feature at 35deg 
  S  which may have lasted until 2011, but that's another subject.) 
  The part that is relevant here is the noticeable quasi-periodic 
  line-to-line and column-to-column variation.

There are images Nasaview won't open properly 

  C1138739_GEOMED
  C1138746_GEOMED
  C1138755_GEOMED

  These images open with a severely wrong stretch -- essentially all 
  black.  Attempting to obtain a histogram frequently causes Nasaview 
  to crash.

  I've already mentioned my lack of enamoration with Nasaview.  I 
  can't see any significant difference between the .LBL files for 
  these images and 1138727 or 1138733, which it opens fine.  But if 
  you know anybody involved with Nasaview, you might want to try and 
  find out what it's choking on.

What are all the bright specks?  

  Image on the right: your C1139221_GEOMED.IMG
  Image on the left:  my own copy of the same image

  Both have the same stretch (-0.02 to 0.32).

  Same region of both is shown [_FITS_ coordinates 200,625 (upper 
  left) to 400,500 (lower right); also shown by the blue rectangle in 
  the thumbnail at the upper right of the window].

  Your version has a lot of bright speckles in it that don't have to 
  be there.  The region I selected contains three.