Mike,

This process is known as image correlation and is an extremely complex area of image processing and analysis.

We use the LeadTools functionality to do this as it is extremely flexible, for example it will return you a vector of all occurances of the source image found in the destination.

short Correlation(ILEADRaster *pRaster, 
                  ILEADRaster *pCorrelationRaster, 
                  short StepX, 
                  short StepY, 
                  short Threshold);

Regards
Neil