diff --git a/modules/core/doc/basic_structures.rst b/modules/core/doc/basic_structures.rst
index ca9f5e21a2..acfbb911d2 100644
--- a/modules/core/doc/basic_structures.rst
+++ b/modules/core/doc/basic_structures.rst
@@ -1691,7 +1691,7 @@ Returns the depth of a matrix element.
 
 .. ocv:function:: int Mat::depth() const
 
-The method returns the identifier of the matrix element depth (the type of each individual channel). For example, for a 16-bit signed 3-channel array, the method returns ``CV_16S`` . A complete list of matrix types contains the following values:
+The method returns the identifier of the matrix element depth (the type of each individual channel). For example, for a 16-bit signed element array, the method returns ``CV_16S`` . A complete list of matrix types contains the following values:
 
 * ``CV_8U``     - 8-bit unsigned integers ( ``0..255``     )
 
diff --git a/modules/features2d/doc/common_interfaces_of_descriptor_matchers.rst b/modules/features2d/doc/common_interfaces_of_descriptor_matchers.rst
index 8596ae43db..d7e5eb4c29 100644
--- a/modules/features2d/doc/common_interfaces_of_descriptor_matchers.rst
+++ b/modules/features2d/doc/common_interfaces_of_descriptor_matchers.rst
@@ -217,7 +217,7 @@ For each query descriptor, finds the training descriptors not farther than the s
 
     :param compactResult: Parameter used when the mask (or masks) is not empty. If  ``compactResult``  is false, the  ``matches``  vector has the same size as  ``queryDescriptors``  rows. If  ``compactResult``  is true, the  ``matches``  vector does not contain matches for fully masked-out query descriptors.
 
-    :param maxDistance: Threshold for the distance between matched descriptors.
+    :param maxDistance: Threshold for the distance between matched descriptors. Distance means here metric distance (e.g. Hamming distance), not the distance between coordinates (which is measured in Pixels)!
 
 For each query descriptor, the methods find such training descriptors that the distance between the query descriptor and the training descriptor is equal or smaller than ``maxDistance``. Found matches are returned in the distance increasing order.
 
diff --git a/modules/highgui/src/window.cpp b/modules/highgui/src/window.cpp
index 6d29534643..1e47bf6ee3 100644
--- a/modules/highgui/src/window.cpp
+++ b/modules/highgui/src/window.cpp
@@ -256,12 +256,17 @@ namespace
 
 void cv::imshow( const string& winname, InputArray _img )
 {
+    const Size size = _img.size();
 #ifndef HAVE_OPENGL
-    Mat img = _img.getMat();
-    CvMat c_img = img;
-    cvShowImage(winname.c_str(), &c_img);
+    CV_Assert(size.width>0 && size.height>0);
+    {
+        Mat img = _img.getMat();
+        CvMat c_img = img;
+        cvShowImage(winname.c_str(), &c_img);
+    }
 #else
     const double useGl = getWindowProperty(winname, WND_PROP_OPENGL);
+    CV_Assert(size.width>0 && size.height>0);
 
     if (useGl <= 0)
     {
@@ -275,7 +280,6 @@ void cv::imshow( const string& winname, InputArray _img )
 
         if (autoSize > 0)
         {
-            Size size = _img.size();
             resizeWindow(winname, size.width, size.height);
         }