Image Comparison Result show only White background in exported mht or in Test excute logs

Image Comparison Result shows only White background in exported mht   but I see 

TestComplete has three comparison modes:

•  
   White background - when selected, TestComplete fills identical pixels with white color.
•  
   Light background - when selected, TestComplete lightens identical pixels
•  
   Dark background - when selected, TestComplete darkens identical pixels

It would be more clear if this option available in mht export format as white background difference is not clear and need to look at actual image to see exact difference.