Restored function to rescale pixel values before imshow

modules/highgui/src/precomp.hpp

@@ -123,4 +123,39 @@ double cvGetOpenGlProp_QT(const char* name);
 double cvGetPropVisible_QT(const char* name);
 #endif
 
+inline void convertToShow(const cv::Mat &src, cv::Mat &dst, bool toRGB = true)
+{
+    const int src_depth = src.depth();
+    CV_Assert(src_depth != CV_16F && src_depth != CV_32S);
+    cv::Mat tmp;
+    switch(src_depth)
+    {
+    case CV_8U:
+        tmp = src;
+        break;
+    case CV_8S:
+        cv::convertScaleAbs(src, tmp, 1, 127);
+        break;
+    case CV_16S:
+        cv::convertScaleAbs(src, tmp, 1/255., 127);
+        break;
+    case CV_16U:
+        cv::convertScaleAbs(src, tmp, 1/255.);
+        break;
+    case CV_32F:
+    case CV_64F: // assuming image has values in range [0, 1)
+        cv::convertScaleAbs(src, tmp, 256.);
+        break;
+    }
+    cv::cvtColor(tmp, dst, toRGB ? cv::COLOR_BGR2RGB : cv::COLOR_BGRA2BGR, dst.channels());
+}
+
+inline void convertToShow(const cv::Mat &src, const CvMat* arr, bool toRGB = true)
+{
+    cv::Mat dst = cv::cvarrToMat(arr);
+    convertToShow(src, dst, toRGB);
+    CV_Assert(dst.data == arr->data.ptr);
+}
+
+
 #endif /* __HIGHGUI_H_ */

modules/highgui/src/window_QT.cpp

@@ -2556,17 +2556,7 @@ void DefaultViewPort::updateImage(const CvArr* arr)
 
     nbChannelOriginImage = cvGetElemType(mat);
     CV_Assert(origin == 0);
-    cv::Mat src = cv::cvarrToMat(mat), dst = cv::cvarrToMat(image2Draw_mat);
-
-    cv::Mat tmp;
-    int src_depth = src.depth();
-    double scale = src_depth <= CV_8S ? 1 : src_depth <= CV_32S ? 1./256 : 255;
-    double shift = src_depth == CV_8S || src_depth == CV_16S ? 128 : 0;
-    cv::convertScaleAbs(src, tmp, scale, shift);
-
-    cv::cvtColor(tmp, dst, cv::COLOR_BGR2RGB, dst.channels());
-    CV_Assert(dst.data == image2Draw_mat->data.ptr);
-
+    convertToShow(cv::cvarrToMat(mat), image2Draw_mat);
     viewport()->update();
 }
 

modules/highgui/src/window_cocoa.mm

@@ -946,7 +946,7 @@ static NSSize constrainAspectRatio(NSSize base, NSSize constraint) {
 
     if (bitmap) {
         cv::Mat dst(arrMat.rows, arrMat.cols, CV_8UC3, [bitmap bitmapData], [bitmap bytesPerRow]);
-        cv::cvtColor(arrMat, dst, cv::COLOR_BGR2RGB);
+        convertToShow(arrMat, dst);
     }
     else {
         // It's not guaranteed to like the bitsPerPixel:24, but this is a lot slower so we'd rather not do it
@@ -960,8 +960,8 @@ static NSSize constrainAspectRatio(NSSize base, NSSize constraint) {
             colorSpaceName:NSDeviceRGBColorSpace
             bytesPerRow:(arrMat.cols * 4)
             bitsPerPixel:32];
-        cv::Mat dst(arrMat.rows, arrMat.cols, CV_8UC3, [bitmap bitmapData], [bitmap bytesPerRow]);
-        cv::cvtColor(arrMat, dst, cv::COLOR_BGR2RGBA);
+        cv::Mat dst(arrMat.rows, arrMat.cols, CV_8UC4, [bitmap bitmapData], [bitmap bytesPerRow]);
+        convertToShow(arrMat, dst);
     }
 
     if( image ) {

modules/highgui/src/window_gtk.cpp

@@ -141,9 +141,7 @@ void cvImageWidgetSetImage(CvImageWidget * widget, const CvArr *arr){
         gtk_widget_queue_resize( GTK_WIDGET( widget ) );
     }
     CV_Assert(origin == 0);
-    cv::Mat src = cv::cvarrToMat(arr), dst = cv::cvarrToMat(widget->original_image);
-    cv::cvtColor(src, dst, cv::COLOR_BGR2RGB, dst.channels());
-    CV_Assert(dst.data == widget->original_image->data.ptr);
+    convertToShow(cv::cvarrToMat(arr), widget->original_image);
     if(widget->scaled_image){
         cvResize( widget->original_image, widget->scaled_image, CV_INTER_AREA );
     }

modules/highgui/src/window_w32.cpp

@@ -1206,18 +1206,10 @@ cvShowImage( const char* name, const CvArr* arr )
     }
 
     {
-        cv::Mat src = cv::cvarrToMat(image);
         cv::Mat dst(size.cy, size.cx, CV_8UC3, dst_ptr, (size.cx * channels + 3) & -4);
-
-        cv::Mat tmp;
-        int src_depth = src.depth();
-        double scale = src_depth <= CV_8S ? 1 : src_depth <= CV_32S ? 1./256 : 255;
-        double shift = src_depth == CV_8S || src_depth == CV_16S ? 128 : 0;
-        cv::convertScaleAbs(src, tmp, scale, shift);
-        cv::cvtColor(tmp, dst, cv::COLOR_BGRA2BGR, dst.channels());
-        cv::flip(dst, dst, 0);
-
+        convertToShow(cv::cvarrToMat(image), dst, false);
         CV_Assert(dst.data == (uchar*)dst_ptr);
+        cv::flip(dst, dst, 0);
     }
 
     // ony resize window if needed