diff --git a/imageviewer-qt4.cpp b/imageviewer-qt4.cpp
index 2add697..972da2e 100644
--- a/imageviewer-qt4.cpp
+++ b/imageviewer-qt4.cpp
@@ -286,6 +286,31 @@ void ImageViewer::adjustBrightness(int b) {
   renewLogging();
 }
 
+/**
+ * Fired by the constrast_slider, this one adjusts the contrast on image.
+ * @brief ImageViewer::adjustContrast
+ */
+void ImageViewer::adjustContrast(int c) {
+  int h, s, old_l;
+  int new_l = 0;
+  int delta = c - 255;
+  for(int x=0; x<image->width(); x++) {
+    for(int y=0; y<image->height(); y++) {
+//       QColor color = QColor::fromRgb(original_image->pixel(x, y));
+//       color.getHsl(&h, &s, &old_l);
+//       new_l = old_l + delta;
+//       if(new_l > 255) new_l = 255;
+//       if(new_l < 0) new_l = 0;
+//       color.setHsl(h, s, new_l);
+//       image->setPixel(x, y, color.rgba());
+    }
+  }
+  updateImageDisplay();
+  logFile << "[TODO!] Contrast adjusted to: " << old_l << " + " << delta << " -> (" << h << ", " << s << ", " << new_l << ")" << std::endl;
+  renewLogging();
+}
+
+
 /**************************************************************************************** 
 *   
 *  GUI elements related to the tasks are set up here.
@@ -353,8 +378,9 @@ void ImageViewer::generateControlPanels() {
   
   contrast_slider = new QSlider(Qt::Horizontal);
   contrast_slider->setMinimum(0);
-  contrast_slider->setMaximum(255);
-  contrast_slider->setValue(127);
+  contrast_slider->setMaximum(510);
+  contrast_slider->setValue(255);
+  QObject::connect(contrast_slider, SIGNAL(valueChanged(int)), this, SLOT (adjustContrast(int)));
 
   task_tab2->addWidget(task_tab2_stats);
   task_tab2->addWidget(new QLabel("Histogramm"));
diff --git a/imageviewer-qt4.h b/imageviewer-qt4.h
index e108d64..243758b 100644
--- a/imageviewer-qt4.h
+++ b/imageviewer-qt4.h
@@ -108,6 +108,7 @@ class ImageViewer : public QMainWindow {
     void analyzeImage();
     void updateHistogramm();
     void adjustBrightness(int b);
+    void adjustContrast(int c);
 
     void open();
     void print();