Option Fftwsigma (true) to have substantially the same results FFTW Gaussianblur

rtengine/iplocalcontrast.cc

@@ -33,6 +33,8 @@
 
 namespace rtengine
 {
+    extern const Settings* settings;
+    
     LocallabParams          locallab;        ///< Local lab parameters
 
 void ImProcFunctions::localContrast(LabImage *lab, float **destination, const LocalContrastParams &localContrastParams, bool fftwlc, double scale)
@@ -59,11 +61,15 @@ void ImProcFunctions::localContrast(LabImage *lab, float **destination, const Lo
         //emprical adjustement between FFTW radius and Gaussainblur
         //under 50 ==> 10.f
         //above 400 ==> 1.f
+        if(settings->fftwsigma == false) {//empirical formula
             float ak = -9.f / 350.f;
             float bk = 10.f - 50.f * ak;
             kr = ak * sigma + bk;
             if(sigma < 50.f) kr = 10.f;
             if(sigma > 400.f) kr = 1.f;
+        } else {//sigma *= sigma
+            kr = sigma;
+        }
      //   printf("kr=%f \n", kr);
         ImProcFunctions::fftw_convol_blur2(lab->L, buf, width, height, kr * sigma, 0, 0);
     }

rtengine/iplocallab.cc

@@ -4010,7 +4010,8 @@ void ImProcFunctions::fftw_convol_blur(float *input, float *output, int bfw, int
     ** n_x n_y relative width and high for kernel
     ** Gaussian blur is given by G(x,y) = (1/2*PI*sigma) * exp(-(x2 + y2) / 2* sigma2)
     ** its traduction in Fourier transform is G(x,y) =  exp((-sigma)*(PI * x2 + PI * y2)), for some authors it is not sigma but sigma^2..I have tried...huge diffrences with Gaussianblur
-    ** after several test the only result that works very well is with fftkern = 0 and algo = 0, and as there is big differences with Gaussianblur, I put an empirical correction in Ipretinex and Iplocalcontrast
+    ** after several test the only result that works very well is with fftkern = 0 and algo = 0, and as there is differences with Gaussianblur, I put an empirical correction in Ipretinex and Iplocalcontrast
+    ** you can enabled or disabled this function with rtsettings.fftwsigma in options. By defaut empirical formula is disabled
     ** in fact no importance....if it is this function (for sigma) or another... we are not in research :)
 */
     BENCHFUN
@@ -4100,7 +4101,7 @@ void ImProcFunctions::fftw_convol_blur(float *input, float *output, int bfw, int
             for(int j = 0; j < bfh; j++){
                 int index = j * bfw;
                 for(int i = 0; i < bfw; i++)
-                    out[i + index] *= exp((float)(-radius)*(n_x * i * i + n_y * j * j));//apply Gauss kernel whithout FFT - some authors says radius*radius but huge differences with Gaussianblur
+                    out[i + index] *= exp((float)(-radius)*(n_x * i * i + n_y * j * j));//apply Gauss kernel whithout FFT - some authors says radius*radius but differences with Gaussianblur
             } 
         } else if(algo == 1) {
 #ifdef _OPENMP

rtengine/ipretinex.cc

@@ -969,7 +969,9 @@ void ImProcFunctions::MSRLocal(int sp, bool fftw, int lum, LabImage * bufreti, L
             //emprical adjustement between FFTW radius and Gaussainblur
             //under 50 ==> 10.f
             // 400 ==> 1.f
-            float sigm = RetinexScales[scale];
+            float sigm = 1.f;
+            if(settings->fftwsigma == false) {//empirical formula
+                sigm = RetinexScales[scale];
                 float ak = -9.f / 350.f;
                 float bk = 10.f - 50.f * ak;
                 kr = ak * sigm + bk;
@@ -988,7 +990,10 @@ void ImProcFunctions::MSRLocal(int sp, bool fftw, int lum, LabImage * bufreti, L
                     }
                 
                 }
-           
+            } else {//sigma *= sigma
+                    kg = 1.f;
+                    kr = sigm;
+            }
         if(!fftw) {
 #ifdef _OPENMP
             #pragma omp parallel  //disabled with FFTW

rtengine/settings.h

@@ -84,6 +84,7 @@ public:
     double          reduchigh;
     double          reduclow;
     bool            detectshape;
+    bool            fftwsigma;
     int             previewselection;
     double          cbdlsensi;
 //    bool            showtooltip;

rtgui/options.cc

@@ -596,6 +596,7 @@ void Options::setDefaults()
     rtSettings.detectshape = true;//experimental new detection shape
     rtSettings.previewselection = 5;//betwen 1 to 40
     rtSettings.cbdlsensi = 1.0;//betwen 0.001 to 1
+    rtSettings.fftwsigma = true; //choice between sigma^2 or empirical formula
 
 // end locallab
 
@@ -760,6 +761,10 @@ void Options::readFromFile(Glib::ustring fname)
                     rtSettings.detectshape = keyFile.get_boolean("General", "Detectshape");
                 }
 
+                if (keyFile.has_key("General", "Fftwsigma")) {
+                    rtSettings.fftwsigma = keyFile.get_boolean("General", "Fftwsigma");
+                }
+
                 if (keyFile.has_key("General", "Cropsleep")) {
                     rtSettings.cropsleep          = keyFile.get_integer("General", "Cropsleep");
                 }
@@ -1988,6 +1993,7 @@ void Options::saveToFile(Glib::ustring fname)
         keyFile.set_double("General", "Reduchigh", rtSettings.reduchigh);
         keyFile.set_double("General", "Reduclow", rtSettings.reduclow);
         keyFile.set_boolean("General", "Detectshape", rtSettings.detectshape);
+        keyFile.set_boolean("General", "Fftwsigma", rtSettings.fftwsigma);
 
         keyFile.set_integer("External Editor", "EditorKind", editorToSendTo);
         keyFile.set_string("External Editor", "GimpDir", gimpDir);