Hi libtiff developers!

   We're now building libtiff v4.6.0 with libjpeg-turbo (instead of libjpeg 
v6b).

   Many thanks to Bob F. for his previous help with modifying libtiff/configure 
to allow us to build with our modified libjpeg-turbo shared library prefix!

   But with our libtiff v4.6.0 built with libjpeg-turbo, I'm now getting an 
error in our MATLAB imread function when reading a "linearRaw" subImage from 
one of our TIFF test files which is a linear DNG file.  This does not error 
with libtiff 4.6.0 built with libjpeg v6b.

  I'm not a linearDNG expert, but here's the overview of the file:

  *   The TIFF file has a main image of type TIFF, and two sub images.
  *
The main image is an 8-bit TIFF image with colortype/photometric interpretation 
RGB, and is uncompressed.
  *   The first subIFD is a Tiled 16-bit TIFF image with colortype/photometric 
interpretation "linearRaw", and is JPEG compressed.
  *   The second subIFD is an 8-bit TIFF image bit with colortype/photometric 
interpretration YCbCr and is JPEG compressed.

  Our imread function successfully reads the main image and the second subIFD.  
But when reading the first subIFD, something goes awry – it ends up calling 
libtiff's TIFFReadTile function in tif_read.c, which then calls 
TIFFReadEncodedTile (also in tif_read.c).  I haven't debugged further yet, but 
something fails during TIFFReadEncodedTile which results in our imread function 
give error that the file has no readable tiles.

  I'm wondering if you know what may be going wrong here, and/or if there are 
any limitations with libtiff built with libjpeg-turbo that would cause problems 
reading a 16-bit linearRaw subIFD that is JPEG compressed.

  Any help would be appreciated.

  Thank you!

     ellen


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