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]

OK, I see your problem. The "Center of Projection" longitude has nothing to do with where the image is centered. It has to do with how the image is projected -- sinusoidal projection is a projection where only one line of longitude is vertical, and all other longitude lines are sinusoidal curves that converge toward the pole. Typically you want the center of projection to be the center longitude of the image, which is the mapaplanet default; there's only rare circumstances where you'd want to specify a different longitude (mostly having to do with building large mosaics out of several chunks).

Here's how I find your volcanoes. Go to http://www.mapaplanet.org/explorer/venus.html. Pick Left-Look FMAPs. Click Advanced Options. You want a map centered at about 12 north, 8 east. So I'd put in 22, 2 for north and south and -2, 18 for east and west and click "Submit Changes." Oops, I get an image only 40 pixels square. No problem, I just bump the resolution up from 2 pix/deg to 100 pix/deg. Go away for a few minutes while it thinks. Curse when I come back and it tells me the "connection was reset." Bump the resolution to 50 pix/deg, and in 5 seconds I have a nice picture and I see those pancake volcanoes right in the middle. Use the mouse to draw a bounding box around the area I'm interested in and it automatically zooms, using the pixel extent of my previous map. I ask it for a gaussian stretch and bump the resolution up a bit more, to half the full resolution (704 pix/deg) and attached is what I get (warning, it's 4 MB). There is a link at lower right where you can view it as a JPEG; using the "shopping cart" you can download it in a lossless format. For illustration purposes here's one at 10% the full resolution.

Because the area you picked in this example sits on the equator, mapaplanet defaulted to showing it in simple cylindrical projection rather than sinusoidal, so the "center of projection" thing is completely meaningless, by the way.

The whole process (including writing this post) took me about 7 min.

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[ncc1701d]

Thank you. I found it.
Just out of curiosity did you think the pdsmaps was easier to use or does it make a difference in your mind given your expertise in the business?