How to compare two color histogram

Question

I used a map<CString, vector<double>> structure to store the mapping of file name to its HSV color histogram.And there are 100 elements in this map as a image DB.If now comes a image,and I have get the input image's histogram,how can I do the compare?

I know a method called "quadratic distance", but I do not understand it.

Are you familiar with linear algebra? – Ilmo Euro Jul 04 '12 at 06:00 — Ilmo Euro, Jul 04 '12 at 06:00
Learned in college,but,it is 4 yrs ago...@llmo – zxi Jul 04 '12 at 06:06 — zxi, Jul 04 '12 at 06:06

score 1 · Accepted Answer · answered Jul 04 '12 at 06:10

1

One simple method would be using a distance calculator like this:

double dist(vector<double> *histogram1, vector<double> *histogram2) {
    double result = 0.0;
    for (vector<double>::iterator val1=histogram1->begin(), val2=histogram2->begin();
         val1<histogram1->end();
         val1++, val2++) {
        result += (*val1 - *val2) * (*val1 - *val2);
    }
    result = sqrt(result);
    return result;
}

And then determine which histogram has the smallest distance. Please note that this is for demonstration purposes only, you must add vector size checks etc.

answered Jul 04 '12 at 06:10

Ilmo Euro

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Simple and useful,I will have a try...Thanks.Why the sqrt func is used here ?@llmoEuro – zxi Jul 04 '12 at 06:17
If you treat the two histograms as n-dimensional points (in the mathematical sense), this function gives their Euclidean distance using the generalized Pythagorean theorem, and `sqrt()` is part of it. If you only need to find the one with the smallest distance, you don't need it, because if `sqrt(a) < sqrt(b)` then `a < b`. – Ilmo Euro Jul 04 '12 at 08:10

How to compare two color histogram

1 Answers1