2008-01-08

Rawtran

A digital photography is really amazing field of a new technology. I discovered another dimension of one during winter's holiday while I'm play with analyzing of pictures by a standard fotometrical way. I get view to a complicated world of a calibration of that devices. My first touch has been of a most lower level: a conversion of RAW images produced by a digital camera to my favorite FITS format.

A great part of known RAW formats should be recognized and decoded by famous utility dcraw. It satisfy most of my requirements but one creates no FITSes. Dave's recommended way how to transform dcraw's output PGM files to FITS is not ideal. The issue is a netpbm toolkit with a "non-astronomer's" conversion.

My response for the frustration is a small utility Rawran. It wraps of the dcraw, get a PGM data file via a pipe and rearrange the data in fashion:
  • a four RGGB pixels to intensity as a weighted sum
  • one to one data pixels
  • a three separate bands in one file

The utility is not too mature and it can be found in rawtran directory along my other projects.

Some examples of converted images by the first method can be found as FITS files (each about 6M): holmes.fits (zoomed parts of the images has been used in examples above), pleiades.fits, deeep_macocha.fits (a png version of the image has been published some time ago).
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