Floating point TIFF and other enhancements

GraphicsMagick CVS and the latest development snapshot (available via 
ftp) now support TIFF files in IEEEFP sample format (SampleFormat=3). 
Both 'short' and 'double' types are supported.  Photometric 
interpretations may be MINISWHITE, MINISBLACK, RGB, or SEPARATED 
(CMYK).  Files like this are used by the scientific community, and for 
remote sensing applications.

The SMinSampleValue and SMaxSampleValue TIFF tags are used to record 
the minimum and maximum sample values used.  They will be used when 
reading a file (if present).  There is no prescan support when 
reading, so if the tags are not present, or the data does not span 0.0 
to 1.0, manual intervention (see below) may be required.  Manual 
adjustments may also be used to provide a crude image adjustment 
capability when reading.

In order to support the feature, several defines (-define) are 
extended or added:

   o tiff:sample-format={unsigned|ieeefp} is used to select the output
     sample format.

   o tiff:bits-per-sample is extended to support 32 or 64 bits when the
     sample format is "ieeefp" (1-32 for "unsigned" format).

   o tiff:max-sample-value is used to specify the maximum sample value
     when reading or writing (default is 1.0).

   o tiff:min-sample-value is used to specify the minimum sample value
     when reading or writing (default is 0.0).  Negative values seem to
     work ok.

The ExportImagePixelArea() and ImportImagePixelArea() APIs are 
enhanced to support exporting or importing floating point samples in 
native endian order.

In case anyone missed it, both associated and unassociated alpha are 
now supported.  There is now a versatile tiled TIFF reader/writer.

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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