DPX and Kodak Cineon are the two professional raster image formats used in
digital cinema/film post-production facilities to professionally store video
frames, usually using RGB, YUV or XYZ colour-spaces with 10,12,16 or 32 bits
per channel. They have two functions:

   1. They store complete colorimetry information in order to guarantee
   perfect colour reproduction across different media (monitors, projectors,
   paper and film stock). In particular they are used when conversions between
   original negative film to print film (for theatrical releases) require
   colours stored as film density, which is a nonlinear function compared to
   linear colour spaces used for video
   2. They are to cinema like RAW images are to photography: using such high
   color depths it is possible to store even the slightest lightness/colour
   differences in order for post-production to better manage color corrections
   and VFXs

Thanks for the support: it is my first post here. I'll read the patches
section and send a diff file for the original imghdr.py module.

I apologize for mixed tab/space indents: I checked for them (I use \t's) but
apparently missed some. As far as h and f they are pretty useless names for
me too, but was just adapting to the names in the core imghdr.py module
(which also imports modules within the functions).