From 839308fe335645b71d617ed075a0434adfd724ca Mon Sep 17 00:00:00 2001
From: Jan Philipp Timme <jan.philipp@timme.it>
Date: Fri, 4 Dec 2015 14:01:13 +0100
Subject: [PATCH] [TASK] Not quite sure, but partial linear histogramm adaption
 seems to be done.

---
 imageviewer-qt4.cpp | 45 +++++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/imageviewer-qt4.cpp b/imageviewer-qt4.cpp
index e4139a3..7f56a9c 100644
--- a/imageviewer-qt4.cpp
+++ b/imageviewer-qt4.cpp
@@ -375,17 +375,19 @@ void ImageViewer::partialLinearHistogrammAdaption() {
   double* reference_histogramm = histogramm_reference->getRelativeCumulativeIntensityHistogramm();
   
   // Split [0,255] into n parts (slider)
+  // This produces a list of brightness indexes to interpolate in between.
   int number_parts = partial_adaption_pieces_slider->value();
-  int* parts = (int*) malloc(number_parts*sizeof(int));
-  for(int i=0; i<number_parts; i++) {
+  int* parts = (int*) malloc((number_parts+1)*sizeof(int));
+  for(int i=0; i<=number_parts; i++) {
     parts[i] = qRound((255.0/number_parts)*i);
     logFile << "I: " << i << ", intensity: " << parts[i] << std::endl;
   }
   
-  // Create
-  // TODO TODO TODO
+  // Create histogramm map
+  // This will point every new brightness index to the old double value
+  // from the reference histogramm. (array with double index, but the other way around :/ )
   double* histogramm_map = (double*) malloc(256*sizeof(double));
-  for(int i=0; i<number_parts; i++) {
+  for(int i=0; i<=number_parts; i++) {
     int current_n = parts[i];
     if(current_n == 0) continue; // First part is always at zero!
     int last_n = parts[i-1];
@@ -393,7 +395,7 @@ void ImageViewer::partialLinearHistogrammAdaption() {
     double delta_i = reference_histogramm[current_n] - reference_histogramm[last_n];
     double m = delta_i / delta_n;
     double offset = histogramm_map[last_n];
-    // Fill in the blanks
+    // Calculate the mapping values
     for(int j=last_n; j<=current_n; j++) {
       int delta_n = j - last_n;
       histogramm_map[j] = (offset + delta_n*m);
@@ -401,20 +403,39 @@ void ImageViewer::partialLinearHistogrammAdaption() {
     }
   }
   
-  // Apply the histogramm map (see succeeding Histogramm Adaption)
-  /*
+  // Build up the brightness map to apply on the image
+  // (basically reversing and applying the histogramm map)
+  int* brightness_map = (int*) malloc(256*sizeof(int));
+  for(int i=0; i<256; i++) {
+    double old_brightness_occurrence = reference_histogramm[i];
+    int j = 0;
+    for(j=0; j<256; j++) {
+      if(old_brightness_occurrence < histogramm_map[j]) break;
+    }
+    if(j > 255) j = 255;
+    brightness_map[i] = j;
+  }
+  
+  for(int i=0; i<256; i++) {
+    logFile << i << " -> " << brightness_map[i] << std::endl;
+  }
+  renewLogging();
+
+  // Apply the brightness map
   int h, s, l;
-  int pixels = working_copy->getImage()->width() * working_copy->getImage()->height();
   for(int x=0; x<working_copy->getImage()->width(); x++) {
     for(int y=0; y<working_copy->getImage()->height(); y++) {
       QColor color = QColor::fromRgb(original->getImage()->pixel(x, y));
       color.getHsl(&h, &s, &l);
-      l = qRound(histogramm_map[l] * (255/pixels));
+      l = brightness_map[l];
       color.setHsl(h, s, l);
       working_copy->getImage()->setPixel(x, y, color.rgb());
     }
-  }*/
+  }
+
+  
   // Done.
+  free(brightness_map);
   free(histogramm_map);
   free(parts);
   logFile << "done." << std::endl;
@@ -788,7 +809,7 @@ void ImageViewer::generateControlPanels() {
   
   partial_adaption_pieces_slider = new QSlider(Qt::Horizontal);
   partial_adaption_pieces_slider->setMinimum(2);
-  partial_adaption_pieces_slider->setMaximum(10);
+  partial_adaption_pieces_slider->setMaximum(20);
   partial_adaption_pieces_slider->setValue(5);
   //QObject::connect(partial_adaption_pieces_slider, SIGNAL(valueChanged(int)), this, SLOT(robustAutomaticContrastAdaption(int)));