Linked red and blue exponent adjuster to the green adjuster, in order to maintain the ratio between exponents if the user moves the green adjuster (master).

Switched back to vector sort for median calculations: the results of the histogram search function diverge more and more from the simple median calculation as the exponents increase.
At 2.0 the test picture is already impossible to WB as the multipliers are too far off (2.78226e+08 histo vs 9.7927e+11 sort), and the normal WB sliders can't compensate for those huge factors.

rtengine/filmnegativeproc.cc

@@ -104,8 +104,8 @@ bool RawImageSource::getFilmNegativeExponents (Coord2D spotA, Coord2D spotB, int
       std::swap(clearVals, denseVals);
 
     if (settings->verbose) {
-        printf("Clear film values:  R=%f G=%f B=%f\n", clearVals[0], clearVals[1], clearVals[2]);
+        printf("Clear film values:  R=%g G=%g B=%g\n", clearVals[0], clearVals[1], clearVals[2]);
-        printf("Dense film values:  R=%f G=%f B=%f\n", denseVals[0], denseVals[1], denseVals[2]);
+        printf("Dense film values:  R=%g G=%g B=%g\n", denseVals[0], denseVals[1], denseVals[2]);
     }
 
     float denseGreenRatio = clearVals[1] / denseVals[1];
@@ -119,7 +119,7 @@ bool RawImageSource::getFilmNegativeExponents (Coord2D spotA, Coord2D spotB, int
             newExps[ch] = CLAMP(logBase(clearVals[ch] / denseVals[ch], denseGreenRatio), 0.3f, 3.f);
 
     if (settings->verbose)
-        printf("New exponents:  R=%f G=%f B=%f\n", newExps[0], newExps[1], newExps[2]);
+        printf("New exponents:  R=%g G=%g B=%g\n", newExps[0], newExps[1], newExps[2]);
 
     return true;
 }
@@ -230,20 +230,23 @@ void RawImageSource::filmNegativeProcess(const procparams::FilmNegativeParams &p
     float mults[3] = { 1.f };  // Channel normalization multipliers
 
     for (int c=0; c<3; c++) {
-        // Find median values for each channel using a histogram search function
+        // Find median values for each channel
-        findMinMaxPercentile(&cvs[c][0], cvs[c].size(), 0.5f, medians[c], 0.5f, medians[c], true);
+        if(cvs[c].size() > 0) {
-        // Determine the channel multipler so that N times the median becomes 65k. This clips away
+            std::sort(cvs[c].begin(), cvs[c].end());
-        // the values in the dark border surrounding the negative (due to the film holder, for example),
+            medians[c] = cvs[c].at(cvs[c].size() / 2);
-        // the reciprocal of which have blown up to stellar values.
+            // Determine the channel multipler so that N times the median becomes 65k. This clips away
-        mults[c] = MAX_OUT_VALUE / (medians[c] * 24);
+            // the values in the dark border surrounding the negative (due to the film holder, for example),
+            // the reciprocal of which have blown up to stellar values.
+            mults[c] = MAX_OUT_VALUE / (medians[c] * 24);
+        }
     }
 
 
     t4.set();
     if (settings->verbose) {
         printf("Sample count : %lu, %lu, %lu\n", cvs[0].size(), cvs[1].size(), cvs[2].size());
-        printf("Medians : %f %f %f\n", medians[0], medians[1], medians[2] );
+        printf("Medians : %g %g %g\n", medians[0], medians[1], medians[2] );
-        printf("Computed multipliers : %f %f %f\n", mults[0], mults[1], mults[2] );
+        printf("Computed multipliers : %g %g %g\n", mults[0], mults[1], mults[2] );
         printf("Median calc time us: %d\n", t4.etime(t3));
     }
 

rtgui/filmnegative.cc

@@ -34,7 +34,7 @@ FilmNegative::FilmNegative () : FoldableToolPanel(this, "filmnegative", M("TP_FI
 {
 
     auto mkExponentAdjuster = [this](Glib::ustring label, double defaultVal) {
-        Adjuster *adj = Gtk::manage(new Adjuster (label, 0.3, 3, 0.01, defaultVal)); //exponent
+        Adjuster *adj = Gtk::manage(new Adjuster (label, 0.3, 5, 0.001, defaultVal)); //exponent
         adj->setAdjusterListener (this);
     
         if (adj->delay < options.adjusterMaxDelay) {
@@ -49,6 +49,9 @@ FilmNegative::FilmNegative () : FoldableToolPanel(this, "filmnegative", M("TP_FI
     greenExp = mkExponentAdjuster(M("TP_FILMNEGATIVE_GREEN"), 1.0);
     blueExp  = mkExponentAdjuster(M("TP_FILMNEGATIVE_BLUE"), 0.86);
 
+    redRatio = redExp->getValue() / greenExp->getValue();
+    blueRatio = blueExp->getValue() / greenExp->getValue();
+
     auto m = ProcEventMapper::getInstance();
     EvFilmNegativeEnabled = m->newEvent(ALL, "HISTORY_MSG_FILMNEGATIVE_ENABLED");
     EvFilmNegativeExponents = m->newEvent(ALL, "HISTORY_MSG_FILMNEGATIVE_EXPONENTS");
@@ -139,10 +142,23 @@ void FilmNegative::enabledChanged()
 
 void FilmNegative::adjusterChanged(Adjuster* a, double newval)
 {
-    if (listener && getEnabled()) {
+    if (listener) {
         if(a == redExp || a == greenExp || a == blueExp) {
-            listener->panelChanged (EvFilmNegativeExponents, Glib::ustring::compose (
+            disableListener();
-                "R=%1 ; G=%2 ; B=%3", redExp->getTextValue(), greenExp->getTextValue(), blueExp->getTextValue()));
+            if(a == greenExp) {
+                redExp->setValue(a->getValue() * redRatio);
+                blueExp->setValue(a->getValue() * blueRatio);
+            } else if(a == redExp) {
+                redRatio = newval / greenExp->getValue();
+            } else if(a == blueExp) {
+                blueRatio = newval / greenExp->getValue();
+            }
+            enableListener();
+            
+            if(getEnabled()) {
+                listener->panelChanged (EvFilmNegativeExponents, Glib::ustring::compose (
+                    "R=%1 ; G=%2 ; B=%3", redExp->getTextValue(), greenExp->getTextValue(), blueExp->getTextValue()));
+            }
         }
     }
 }

rtgui/filmnegative.h

@@ -54,6 +54,8 @@ private:
     Gtk::ToggleButton* spotbutton;
     sigc::connection spotConn;
 
+    double redRatio, blueRatio;
+
     void editToggled ();
 
 public: