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

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

How to set this options in my script by default? Or is this only for Testcomplete and not for exported mht \ Test execute log ? 

I wanted set lightbackground difference result always. Any idea to have this in mht and testexecute logs?