Question

I know the default value for norm_type used when calling the function is 4, but what does this correspond to? The options are NORM_INF, NORM_L1 and NORM_L2. Which of these is 4? And while I’m at it, what are the values for the rest of them? I can’t find #defines for these anywhere.

Answer 1

These are defined in modules/core/include/opencv2/core/core.hpp, as an enum:

enum { NORM_INF=1, NORM_L1=2, NORM_L2=4, NORM_TYPE_MASK=7, NORM_RELATIVE=8, NORM_MINMAX=32};

So default is L2 norm (euclidean).

Also, the OpenCV docs say that the default is NORM_L2.