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May 1997

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1997.05.01 10:35 "tiled-pyramidal-LAB-JPEG-TIFF", by John Cupitt
1997.05.01 14:24 "Re: tiled-pyramidal-LAB-JPEG-TIFF", by Tom Lane

1997.05.01 10:35 "tiled-pyramidal-LAB-JPEG-TIFF", by John Cupitt

Dear TIFF-list,
 
I've added tiled-pyramidal-LAB-JPEG-TIFF (there should be an acronym for this)
to our image processing library and image viewer. It all seems to work fine,
thanks very much for all the great free code, but I have a couple of
questions:

- I'm not using SubIFD and FILETYPE_REDUCEDIMAGE at the moment, I just have
  each layer of my pyramid in a top-level TIFF directory, with the biggest
  first. Does anyone have some simple bit of code I could use as a model for
  creating SubIFD files? I tried reading thumbnail.c, but something even
  simpler would be great.

- Does anyone know of a test image which uses this variant of TIFF? I'd like
  to check I've done it correctly. I can offer a 10k by 10k image of a
  painting taken directly from the object with a calibrated digital camera
  free to anyone interested.
 
- I'm using PHOTOMETRIC_CIELAB, and COMPRESSION_JPEG. Does the JPEG layer know
  about LAB, ie. does it replace its RGB->YCC conversion with something more
  appropriate? I'm getting some sightly funny effects ...
  
All help appreciated, thanks very much,
 
John Cupitt
--
John Cupitt, john@giorgio.hart.bbk.ac.uk, +44 (0)171 930 2108
VASARI Lab, The National Gallery, Trafalgar Square, London, WC2N 5DN