diff --git a/imageviewer-qt4.cpp b/imageviewer-qt4.cpp
index a5c7f25..5f79071 100644
--- a/imageviewer-qt4.cpp
+++ b/imageviewer-qt4.cpp
@@ -715,6 +715,17 @@ void ImageViewer::runCannyEdgeThirdStep(void) {
   canny_edge_machine->doThirdStep();
   updateImageDisplay();  
 }
+
+/**
+ * Apply results of canny edge using unsharp masking.
+ * 
+ * @brief ImageViewer::doUnsharpMasking
+ */
+void ImageViewer::doUnsharpMasking(void) {
+  logFile << "Doing USM ..." << std::endl;
+  renewLogging();
+  updateImageDisplay();
+}
 /**************************************************************************************** 
 *   
 *  GUI elements related to the tasks are set up here.
@@ -1005,6 +1016,9 @@ void ImageViewer::generateControlPanels() {
   t_high_spinbox->setDecimals(5);
   t_high_spinbox->setValue(4.0);
   
+  run_usm = new QPushButton("Apply unsharp masking!");
+  QObject::connect(run_usm, SIGNAL(clicked()), this, SLOT(doUnsharpMasking()));
+ 
   task_tab5_scrolllayout->addWidget(new QLabel("Gauss filter size (NxN)"));
   task_tab5_scrolllayout->addWidget(gauss_filter_size);
   task_tab5_scrolllayout->addWidget(new QLabel("Gauss filter sigma"));
@@ -1017,6 +1031,8 @@ void ImageViewer::generateControlPanels() {
   task_tab5_scrolllayout->addWidget(t_high_spinbox);
   task_tab5_scrolllayout->addWidget(run_canny_edge_third_step);
   task_tab5_scrolllayout->addWidget(run_canny_edge);
+  task_tab5_scrolllayout->addWidget(new QLabel("Unsharp masking"));
+  task_tab5_scrolllayout->addWidget(run_usm);
   
   tabWidget->addTab(task_tab5_widget, "Task #5");
   
diff --git a/imageviewer-qt4.h b/imageviewer-qt4.h
index 921256c..65aa314 100644
--- a/imageviewer-qt4.h
+++ b/imageviewer-qt4.h
@@ -155,6 +155,7 @@ class ImageViewer : public QMainWindow {
     QPushButton* run_canny_edge_first_step;
     QPushButton* run_canny_edge_second_step;
     QPushButton* run_canny_edge_third_step;
+    QPushButton* run_usm;
     
     // "My" space for storing data/results
     LazyImage* original;
@@ -184,6 +185,7 @@ class ImageViewer : public QMainWindow {
     void runCannyEdgeFirstStep(void);
     void runCannyEdgeSecondStep(void);
     void runCannyEdgeThirdStep(void);
+    void doUnsharpMasking(void);
 
     void open();
     void openReference();