[Image-SIG] Comparing images

[Charlie Clark]

Hi,

I need to check lot of images to see if they have the right logo in them.  
Fortunately I know the co-ordinates of where the logo in the image should  
be but I'm not sure on the best way to compare a selection from the image  
with a template. Currently I'm cropping the target image to the right size  
and comparing it with ImageChops.difference() with the template but I'm  
not sure how to interpret the results - I had hoped for either a largely  
black or white image but I'm largely getting the inverse of the logo.

Any tips?

Charlie
-- 
Charlie Clark
Managing Director
Clark Consulting & Research
German Office
Helmholtzstr. 20
Düsseldorf
D- 40215
Tel: +49-211-600-3657
Mobile: +49-178-782-6226