Scale.cpp

#include "Scale.h"

namespace DirectGraphicalModels { namespace fex
{
Mat CScale::get(const Mat &img, SqNeighbourhood nbhd)
{
    int width       = img.cols;
    int height      = img.rows;
    int nChannels   = img.channels();

    Mat res(img.size(), img.type());
    vec_mat_t vChannels;
    split(img, vChannels);

    Mat integralImg;                                                
    for (byte c = 0; c < nChannels; c++) {      
        integral(vChannels[c], integralImg);

        for (int y = 0; y < height; y++) {
            int      y0 = MAX(0, y - nbhd.upperGap);
            int      y1 = MIN(y + nbhd.lowerGap, height - 1);
            byte    *pRes = res.ptr<byte>(y);
            int *pI0 = integralImg.ptr<int>(y0);
            int *pI1 = integralImg.ptr<int>(y1 + 1);
            for (int x = 0; x < width; x++) {
                int     x0 = MAX(0, x - nbhd.leftGap);
                int     x1 = MIN(x + nbhd.rightGap, width - 1);
                int     S = (x1 - x0 + 1) * (y1 - y0 + 1);
                float   med = static_cast<float>(pI1[x1 + 1] - pI1[x0] - pI0[x1 + 1] + pI0[x0]) / S;
                pRes[nChannels * x + c] = static_cast<byte>(med + 0.5f);
            } // x
        } // y
    } // c

    return res; 
}
} }