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TIFF and LibTiff Mail List Archive

Thread

2001.02.17 03:00 "new version of TIFF LogLuv (SGILOG) modules", by Greg Ward
2001.02.17 03:11 "Re: new version of TIFF LogLuv (SGILOG) modules", by Frank Warmerdam

2001.02.17 03:11 "Re: new version of TIFF LogLuv (SGILOG) modules", by Frank Warmerdam

  1. I improved the gamut-mapping function in tif_luv.c for imaginary colors, because some images were being super-saturated on the input side and this resulted in some strange color shifts in the output.
  2. I added a psuedotag in tiff.h to control random dithering during LogLuv encoding. This is turned off by default for 32-bit LogLuv and on for 24-bit LogLuv output. Dithering improves the average color accuracy over the image.
  3. I added a #define for LOG_LUV_PUBLIC, which is enabled by default in tiffio.h, to expose internal routines for converting between LogLuv and XYZ coordinates. This is helpful for writing more efficient, specialized conversion routines, especially for reading LogLuv files.

Since I'm not exactly certain what branch I have of the library, you had best do some careful diff's with your current tiff.h and tiffio.h files before you incorporate these changes. Or if you prefer, I can do it for you.

I am attaching the modified files for your examination/approval/rejection.

Greg,

I have applied your patches with minor edits to avoid warnings. I would appreciate it if you could test what's in CVS now to verify correct operation. I really don't have much of a clue when it comes to LogLuv support.

PS. If you have the time, and an interest in LogLuv, perhaps you could skim over an open bug:

http://bugzilla.remotesensing.org/show_bug.cgi?id=22

Best regards,

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