diff --git a/src/Frame.cpp b/src/Frame.cpp
index e25aa5ad6..24acdc40e 100644
--- a/src/Frame.cpp
+++ b/src/Frame.cpp
@@ -943,7 +943,7 @@ std::shared_ptr<QImage> Frame::GetImage()
 // Convert Qimage to Mat
 cv::Mat Frame::Qimage2mat( std::shared_ptr<QImage>& qimage) {
 
-    cv::Mat mat = cv::Mat(qimage->height(), qimage->width(), CV_8UC4, (uchar*)qimage->bits(), qimage->bytesPerLine()).clone();
+    cv::Mat mat = cv::Mat(qimage->height(), qimage->width(), CV_8UC4, (const uchar*)qimage->constbits(), qimage->bytesPerLine()).clone();
     cv::Mat mat2 = cv::Mat(mat.rows, mat.cols, CV_8UC3 );
     int from_to[] = { 0,0,  1,1,  2,2 };
     cv::mixChannels( &mat, 1, &mat2, 1, from_to, 3 );
diff --git a/src/Frame.h b/src/Frame.h
index e241555ec..75976f17b 100644
--- a/src/Frame.h
+++ b/src/Frame.h
@@ -124,7 +124,7 @@ namespace openshot
 		int64_t max_audio_sample; ///< The max audio sample count added to this frame
 
 #ifdef USE_OPENCV
-		cv::Mat imagecv; ///< OpenCV image. It will be always on BGR format
+		cv::Mat imagecv; ///< OpenCV image. It will always be in BGR format
 #endif
 
 		/// Constrain a color value from 0 to 255
@@ -295,6 +295,8 @@ namespace openshot
 #ifdef USE_OPENCV
 		/// Convert Qimage to Mat
 		cv::Mat Qimage2mat( std::shared_ptr<QImage>& qimage);
+
+		/// Convert OpenCV Mat to QImage
 		std::shared_ptr<QImage> Mat2Qimage(cv::Mat img);
 
 		/// Get pointer to OpenCV Mat image object
diff --git a/src/effects/ObjectDetection.cpp b/src/effects/ObjectDetection.cpp
index d4e1e0778..e21a9a847 100644
--- a/src/effects/ObjectDetection.cpp
+++ b/src/effects/ObjectDetection.cpp
@@ -74,23 +74,24 @@ std::shared_ptr<Frame> ObjectDetection::GetFrame(std::shared_ptr<Frame> frame, i
 	cv::Mat cv_image = frame->GetImageCV();
     std::cout<<"Frame number: "<<frame_number<<"\n\n";
     // Check if frame isn't NULL
-    if(!cv_image.empty()){
-
-        // Check if track data exists for the requested frame
-        if (detectionsData.find(frame_number) != detectionsData.end()) {
-            float fw = cv_image.size().width;
-            float fh = cv_image.size().height;
-
-            DetectionData detections = detectionsData[frame_number];
-            for(int i = 0; i<detections.boxes.size(); i++){
-                cv::Rect_<float> bb_nrml = detections.boxes.at(i);
-                cv::Rect2d box((int)(bb_nrml.x*fw),
-                               (int)(bb_nrml.y*fh),
-                               (int)(bb_nrml.width*fw),
-                               (int)(bb_nrml.height*fh));
-                drawPred(detections.classIds.at(i), detections.confidences.at(i),
-                         box, cv_image);
-            }
+    if(cv_image.empty()){
+        return frame;
+    }
+
+    // Check if track data exists for the requested frame
+    if (detectionsData.find(frame_number) != detectionsData.end()) {
+        float fw = cv_image.size().width;
+        float fh = cv_image.size().height;
+
+        DetectionData detections = detectionsData[frame_number];
+        for(int i = 0; i<detections.boxes.size(); i++){
+            cv::Rect_<float> bb_nrml = detections.boxes.at(i);
+            cv::Rect2d box((int)(bb_nrml.x*fw),
+                           (int)(bb_nrml.y*fh),
+                           (int)(bb_nrml.width*fw),
+                           (int)(bb_nrml.height*fh));
+            drawPred(detections.classIds.at(i), detections.confidences.at(i),
+                     box, cv_image);
         }
     }