Alternatives for Extracting EXIF and JPEG Data from Images

[Roger]

Does anybody have a pointer to a Python library/utility that will 
extract the chrominance and luminance quantization tables from JPG images? 

I have been using the _getexif method from PIL, which works fine, but 
doesn't extract the quantization data.  I am a bit fuzzy on the 
terminology, but the quantization data  seems to be JPEG data rather 
than EXIF data.  One utility that extracts the quantization tables is 
JPEGsnoop -- there is a link to download the utility here:
   http://www.impulseadventure.com/photo/jpeg-quantization.html

The source code for the above isn't available and may not be callable 
from a Python script even  if it were available.

Roger