Compare Hist function lets users to compare two images histograms

Methods:

HISTCMP_CORREL : Correlation

HISTCMP_CHISQR : Chi-Square

HISTCMP_CHISQR_ALT : Alternative Chi-Square

HISTCMP_BHATTACHARYYA : Bhattacharyya Distance

HISTCMP_HELLINGER : Synonym for HISTCMP_BHATTACHARYYA