need help. how to uncompress .img files from magellan Options

[ncc1701d]

Hoping someone can help.
I am trying to uncompress the FMAP .img files which are part of magellans images of venus so I can use a converter program to convert them from sinusodal to cylindrical mapping.

Things I do know is that I can just rename .img to .raw and open in photosho however the converter program newmap.exe which is an old dos program that is provided with the FMAP images requires I think the uncompressed .img files in order to convert sinusodal to cylindrical. I know the .raw didnt work. And I get error saying my .img files are compressed so it wont work.
I know .img files are not cd or dvd image file or so I think becuase I could not open them in MagicISO If they were CD images I would think MagicISO would work but I may be wrong though.
Anyone familiar with what I am trying to do. Any image processing guys out their do this with the magellan FMAPS?
I figure the experts would be here.
thanks

[elakdawalla]

I can't remember if the FMAPs are stored the same way as the MIDRs, but the MIDRs were put in sinusoidal projection and then cut into 56 1024-by-1024 tiles per image; you have to open all 56 tiles as raw (which you can do in Photoshop as Phil said, just skip a couple of lines' worth of bytes to get past the header) to get the image before you can reproject and mosaic adjacent images together. This was a huge headache and I actuallly have a set of 27 CDs I made as a grad student containing Photoshop format (PSD) versions of all the C1-MIDRs where I assembled all 56 tiles for each image.

The map interface at the USGS website -- which was redesigned a couple of years ago -- provides clickable interface to the FMAPs. It is a bit slow but very good in that it can generate really enormous images at your choice of projection. http://www.mapaplanet.org/explorer/venus.html That interface is what I used to create the 3 Venus images I used in my Advent Calendar:
http://planetary.org/blog/article/00002801
http://planetary.org/blog/article/00002834
http://planetary.org/blog/article/00002845