Camera response function(Gamma function) remover.

Author: nynyg

modules/photometric_calib/include/opencv2/photometric_calib/GammaRemover.hpp

@@ -0,0 +1,41 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef _OPENCV_GAMMAREMOVER_HPP
+#define _OPENCV_GAMMAREMOVER_HPP
+
+#include "opencv2/photometric_calib.hpp"
+
+namespace cv { namespace photometric_calib {
+
+class CV_EXPORTS GammaRemover
+{
+public:
+    GammaRemover(const std::string &gammaPath, int w_, int h_);
+
+    Mat getUnGammaImageMat(Mat inputIm);
+    void getUnGammaImageArr(Mat inputIm, std::vector<float> &outImVec);
+
+    inline float* getG()
+    {
+        if(!validGamma) return nullptr;
+        else return G;
+    };
+    inline float* getGInv()
+    {
+        if(!validGamma) return nullptr;
+        else return GInv;
+    };
+
+private:
+    float G[256];
+    float GInv[256];
+    int w,h;
+    bool validGamma;
+};
+
+
+}}
+
+#endif //_OPENCV__GAMMAREMOVER_HPP

modules/photometric_calib/src/GammaRemover.cpp

@@ -0,0 +1,78 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#include "precomp.hpp"
+#include "opencv2/photometric_calib/GammaRemover.hpp"
+
+namespace cv { namespace photometric_calib {
+
+GammaRemover::GammaRemover(const std::string &gammaPath, int w_, int h_)
+{
+    validGamma = false;
+    w = w_;
+    h = h_;
+
+    // check the extension of the time file.
+    CV_Assert(gammaPath.substr(gammaPath.find_last_of(".") + 1) == "yaml" || gammaPath.substr(gammaPath.find_last_of(".") + 1) == "yml");
+
+    FileStorage gammaFile;
+    gammaFile.open(gammaPath, FileStorage::READ);
+    CV_Assert(gammaFile.isOpened());
+
+    FileNode gammaNode = gammaFile["gamma"];
+    CV_Assert(gammaNode.type() == FileNode::SEQ);
+    FileNodeIterator itS = gammaNode.begin(), itE = gammaNode.end();
+    std::vector<float> GInvVec;
+    for (; itS != itE; ++itS)
+        GInvVec.push_back((float)*itS);
+    CV_Assert(GInvVec.size() == 256);
+
+    for(int i=0;i<256;i++) GInv[i] = GInvVec[i];
+    for(int i=0;i<255;i++)
+    {
+        CV_Assert(GInv[i+1] > GInv[i]);
+    }
+    float min = GInv[0];
+    float max = GInv[255];
+    for(int i=0;i<256;i++) GInv[i] = 255.0 * (GInv[i] - min) / (max-min);
+    for(int i=1;i<255;i++)
+    {
+        for(int s=1;s<255;s++)
+        {
+            if(GInv[s] <= i && GInv[s+1] >= i)
+            {
+                G[i] = s+(i - GInv[s]) / (GInv[s+1]-GInv[s]);
+                break;
+            }
+        }
+    }
+    G[0] = 0;
+    G[255] = 255;
+    gammaFile.release();
+    validGamma=true;
+}
+
+Mat GammaRemover::getUnGammaImageMat(Mat inputIm)
+{
+    CV_Assert(validGamma);
+    uchar *inputImArr = inputIm.data;
+    float outImArr[w*h];
+    for (int i = 0; i < w * h; ++i)
+    {
+        outImArr[i] = GInv[inputImArr[i]];
+    }
+    Mat _outIm(h, w, CV_32F, outImArr);
+    Mat outIm = _outIm * (1/255.0f);
+    return outIm;
+}
+
+void GammaRemover::getUnGammaImageArr(Mat inputIm, std::vector<float> &outImVec)
+{
+    CV_Assert(validGamma);
+    uchar *inputImArr = inputIm.data;
+    CV_Assert(outImVec.size() == (unsigned long)w * h);
+    for(int i = 0; i < w * h; i++) outImVec[i] = GInv[inputImArr[i]];
+}
+
+}}