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by Robin Rowe (for Daren Wilson) Dec 21, 2005

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In 2003 Bob Dean of JPL and I (Robin Rowe) discussed support for the VICAR file format in CinePaint. Unfortunately, it was too hard to get an OSS compatible license for the existing C library from JPL.

http://www.openchannelfoundation.org/project/print_license.php?group_id=294&license_id=40

Somebody would have to write the code from scratch. Daren Wilson volunteered in 2005.

VICAR FAQ (thanks to Bob Dean)

  1. How many color channels may VICAR content have?
    • Any number of bands for multispectral data. Color images would typically have 3 bands (in R,G,B order). These are often in separate files but can be combined into the same file in one of three organizations (band sequential, band interleaved by line, band interleaved by pixel - see the file format docs).
  2. What bandwidths?
    • There's no standard on bandwidths or any such for the format per se. Individual missions of course have their own standards. Usually the wavelengths and sometimes bandwidths are listed in the image label (metadata about the image) but that also depends on the mission.
  3. What color depths per channel?
    • For MER we produce float (32-bit float) XYZ products, which contain the XYZ coordinate of every pixel in the image. Very useful for certain things. Double-precision images are even rarer. Floating-point images in general (float, double, complex) are usually used for more science-oriented data. Things like Fourier transforms, temperature fields, coordinate maps, that kind of thing. Of course, you could always do a prescaling to float of some sort, if you really wanted to support doubles. Most such products only bother with byte, and increasingly 16-bit integers (that's really important for current missions like MER). It's somewhat rare to find an ad-hoc vicar implementation that does more.
  4. Is VICAR a still format only or are there VICAR movies, too?
    • Still frame. We have some sets of files which represent a movie, but it's just a collection of still frames.
  5. How is VICAR used today (2003) by NASA? Is it the primary image format?
    • PDS is starting to take over a bit. MER is sort of a transition mission; most of the data is in a "dual-label" PDS/VICAR format (readable by either PDS or VICAR... PDS label first followed by the VICAR label). But the processing programs here at MIPL still use the format (the dual thing is read-only; we write pure VICAR then convert). Most of the data has to be in PDS format eventually for archive.
  6. What other unique image formats does NASA offer?
    • PDS, and for astronomy data (such as Hubble) there's FITS. You can look at pds.jpl.nasa.gov to get started on that... it can be a very complex format in its entirety but the image subset is not all that complicated and is actually very similar to VICAR (that's why the dual-label thing works).
  7. What file extensions do VICAR files use? Is that .img?
    • Unfortunately there really isn't a standard. We use all sorts of things. ".img" is moderately common but that just generically means "image"... it's also used for PDS and several other formats. We often have ".red", ".grn", and ".blu" files for different color bands (they tend to be in separate files, although they can be combined)... but again, no real standard or even much of a convention. Basically, if the first characters in the file are "LBLSIZE", it's a VICAR file. ".vic" is a pretty good indication it might be VICAR, but that's not used all that often (at least not yet).
  8. What content is available to the public in VICAR format?
  9. Are there public files on the Internet that would be good test images for our plug-in?
    • Did you talk to John Wright about that? Because he asked me the same thing, and he said he was in contact with you. (Robin: I haven't kept in touch.)

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