enum cv::HistCompMethods

Overview

Histogram comparison methods More…

#include <imgproc.hpp>

enum HistCompMethods
{
    HISTCMP_CORREL        = 0,
    HISTCMP_CHISQR        = 1,
    HISTCMP_INTERSECT     = 2,
    HISTCMP_BHATTACHARYYA = 3,
    HISTCMP_HELLINGER     = HISTCMP_BHATTACHARYYA,
    HISTCMP_CHISQR_ALT    = 4,
    HISTCMP_KL_DIV        = 5,
};

Detailed Documentation

Histogram comparison methods

Enum Values

HISTCMP_CORREL

Correlation

\[d(H_1,H_2) = \frac{\sum_I (H_1(I) - \bar{H_1}) (H_2(I) - \bar{H_2})}{\sqrt{\sum_I(H_1(I) - \bar{H_1})^2 \sum_I(H_2(I) - \bar{H_2})^2}}\]

where

\[\bar{H_k} = \frac{1}{N} \sum _J H_k(J)\]

and \(N\) is a total number of histogram bins.

HISTCMP_CHISQR

Chi-Square

\[d(H_1,H_2) = \sum _I \frac{\left(H_1(I)-H_2(I)\right)^2}{H_1(I)}\]

HISTCMP_INTERSECT

Intersection

\[d(H_1,H_2) = \sum _I \min (H_1(I), H_2(I))\]

HISTCMP_BHATTACHARYYA

Bhattacharyya distance (In fact, OpenCV computes Hellinger distance, which is related to Bhattacharyya coefficient.)

\[d(H_1,H_2) = \sqrt{1 - \frac{1}{\sqrt{\bar{H_1} \bar{H_2} N^2}} \sum_I \sqrt{H_1(I) \cdot H_2(I)}}\]

HISTCMP_HELLINGER

Synonym for HISTCMP_BHATTACHARYYA.

HISTCMP_CHISQR_ALT

Alternative Chi-Square

\[d(H_1,H_2) = 2 * \sum _I \frac{\left(H_1(I)-H_2(I)\right)^2}{H_1(I)+H_2(I)}\]

This alternative formula is regularly used for texture comparison. See e.g. [67]

HISTCMP_KL_DIV

Kullback-Leibler divergence

\[d(H_1,H_2) = \sum _I H_1(I) \log \left(\frac{H_1(I)}{H_2(I)}\right)\]