获取向量中出现最多的值 <cv::Vec3b> 用C ++

Question

I am now currently storing my RGB values of the image with a vector <cv::Vec3b> .

To avoid confusion, let me try clarify my question more. For instance I have a vector of size 10. And the values stored are as shown:

 Vector address        RGB Values(R,G,B)
    [0][0][0]=         255,255,255
    [1][1][1]=         40,42,40
    [2][2][2]=         40,42,40
    [3][3][3]=         40,42,40
    [4][4][4]=         40,2,60
    [5][5][5]=         9,9,0
    [6][6][6]=         40,2,60
    [7][7][7]=         40,42,40
    [8][8][8]=         255,255,40
    [9][9][9]=         255,255,40

as observed, The most occurring values is (40,42,40). How do I get these values? I wish to find the most occurring RGB values of the vector. Does anybody have any suggestions, code sample on how I can do it? Thanks.

Answer 1

Lets say your 3D array is array[][][] and at some location (x,y) you got R=200, G=100, B=10 then you will increment the value of array[200][100][10] by 1. Lets at some another location also you again get R=200, G=100, B=10 then again you will increment array[200][100][10] by 1 so, now the total value at array[200][100][10] is 2. You will do the same for all pixel location.

Then, at the end you will find the maximum value in your 3D array and lets say that maximum value is 1000 at array[210][15][10] . This represents that the combination of RG and B which occurs maximum number of times is "R=210, G=15, B=10"

So, in short we can say that value at [ ][ ][ ] tells you , how many times the combination [R][G][B] has occurred.

Answer 2

I am not very much acquainted with IP. If its just a matter of getting most numbers of occurring RGB objects then it can be done using sort() and equal_range() algorithms present in algorithm.h header file. In the below snippet I have taken example of vector instead of RGB type. This code snippet can be used for your purpose with some changes to find the count of highest occurring object:

    void main() 
{
    vector<int> vecInt;
    vecInt.push_back(0);
    vecInt.push_back(1);
    vecInt.push_back(2);
    vecInt.push_back(3);
    vecInt.push_back(1);
    vecInt.push_back(1);
    vecInt.push_back(1);
    vecInt.push_back(9);
    vecInt.push_back(1);
    vecInt.push_back(0);
    vecInt.push_back(0);

    sort(vecInt.begin(), vecInt.end());
    vector<int>::iterator it;
    it = vecInt.begin();    

    pair<vector<int>::iterator, vector<int>::iterator> pairIter;

    int count = 0;
    for(; it != vecInt.end(); ++it)
    {
            if(it != vecInt.end() )
            {
                pairIter = equal_range(it, vecInt.end(), *it);
            }

        while(pairIter.first != pairIter.second)
        {
        ++count;
        ++(pairIter.first);
        }


    }

}

equal_count(), works on sorted containers and returns a pair of iterators (a range in the sorted container), which contains the value being searched.

pairIter = equal_range(it, vecInt.end(), *it);

Now, we can get the number of items within that pair of iterator using a loop like:

            while(pairIter.first != pairIter.second)
        {
        ++count;
        ++(pairIter.first);
        }

With some changes in this code, I think will solve your purpose.

Answer 3

I think that you can define a three dimensional array and you can do it as mentioned here: http://www.cplusplus.com/forum/articles/7459/

then extract the values of pixel ( Veb3b pixelValue; )at each location of your image and then based upon the R,G and B values ( rValue = pixelValue[0]; , gValue = pixelValue[1]; , bValue = pixelValue[2]; ) increment the corresponding bin of your 3D array