[magick-developers] Unsigned 16 bit DICOM

[Shane Blackett]

The current DICOM coder, dcm.c, assumes that 12bit and 8bit dicom images 
are unsigned and 16 bit images are signed.

However a field in that standard is intended to specify whether or not 
it is signed,  0x0028 0x0103 "Pixel representation".

I attach a patch against ImageMagick Development Subversion (or 
ImageMagick-6.3.6-2 as it hasn't been updated) which respects this field 
for 16bit images if it is set.  If it isn't set then it falls back to 
the previous hard coded default of signed.

I could extend this to 8bit and 12bit images.
I am aware that some DICOM images identify themselves as unsigned when 
they are signed, but it seems better to respect the field than just 
ignore it.  If some particular special cases which are identified can be 
distinguished then we could add code for that.

Shane.