NDVI.cpp

#include "NDVI.h"
#include "LinearMapper.h"
#include "macroses.h"

namespace DirectGraphicalModels { namespace fex
{
Mat CNDVI::get(const Mat &img, byte midPoint)
{
    DGM_ASSERT_MSG(img.channels() == 3, "Input image has %d channel(s), but must have 3.", img.channels());
    Mat res(img.size(), CV_8UC1);
    vec_mat_t vChannels;
    split(img, vChannels);  

    for (int y = 0; y < res.rows; y++) {
        byte *pRes  = res.ptr<byte>(y);
        byte *pR    = vChannels.at(2).ptr<byte>(y);
        byte *pG    = vChannels.at(1).ptr<byte>(y);
        byte *pB    = vChannels.at(0).ptr<byte>(y);
        for (int x = 0; x < res.cols; x++) {
            float nir   = static_cast<float>(pR[x]);
            float vis   = 0.5f * (static_cast<float>(pG[x]) + static_cast<float>(pB[x]));
            float ndvi = (nir + vis > 0) ? (nir - vis) / (nir + vis) : 0;

            pRes[x] = two_linear_mapper<byte>(ndvi, -1.0f, 1.0f, 0.0f, midPoint);
        }
    } // y

    return res;
}
} }