From 9d558114b4dc863311ca9005be231cb809455bc5 Mon Sep 17 00:00:00 2001 From: giraffedata Date: Sun, 28 Dec 2008 16:24:42 +0000 Subject: Add comments git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@795 9d0c8265-081b-0410-96cb-a4ca84ce46f8 --- converter/other/pamtofits.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'converter/other/pamtofits.c') diff --git a/converter/other/pamtofits.c b/converter/other/pamtofits.c index 04b43c35..7a71ff56 100644 --- a/converter/other/pamtofits.c +++ b/converter/other/pamtofits.c @@ -20,6 +20,12 @@ ** in the FITS header, but do not cause the data to be rescaled. */ +/* + The official specification of FITS format (which is for more than + just visual images) is at + ftp://legacy.gsfc.nasa.gov/fits_info/fits_office/fits_standard.pdf +*/ + #include #include #include @@ -201,6 +207,14 @@ writeRaster(struct pam * const pamP, unsigned int const bitpix, int const offset) { + /* Note: the FITS specification does not give the association between + file position and image position (i.e. is the first pixel in the + file the top left, bottom left, etc.). We use the common sense, + popular order of row major, top to bottom, left to right. This + has been the case and accepted since 1989, but in 2008, we discovered + that Gimp and ImageMagick do bottom to top. + */ + unsigned int plane; for (plane = 0; plane < pamP->depth; ++plane) { -- cgit 1.4.1