Merge pull request #2138 from alekcac:python_tutorial_fix

doc/py_tutorials/py_gui/py_drawing_functions/py_drawing_functions.rst

@@ -33,21 +33,21 @@ To draw a line, you need to pass starting and ending coordinates of line. We wil
     img = np.zeros((512,512,3), np.uint8)
 
     # Draw a diagonal blue line with thickness of 5 px
-    img = cv2.line(img,(0,0),(511,511),(255,0,0),5)
+    cv2.line(img,(0,0),(511,511),(255,0,0),5)
 
 Drawing Rectangle
 -------------------
 To draw a rectangle, you need top-left corner and bottom-right corner of rectangle. This time we will draw a green rectangle at the top-right corner of image.
 ::
 
-    img = cv2.rectangle(img,(384,0),(510,128),(0,255,0),3)
+    cv2.rectangle(img,(384,0),(510,128),(0,255,0),3)
 
 Drawing Circle
 ----------------
 To draw a circle, you need its center coordinates and radius. We will draw a circle inside the rectangle drawn above.
 ::
 
-    img = cv2.circle(img,(447,63), 63, (0,0,255), -1)
+    cv2.circle(img,(447,63), 63, (0,0,255), -1)
 
 Drawing Ellipse
 --------------------
@@ -55,7 +55,7 @@ Drawing Ellipse
 To draw the ellipse, we need to pass several arguments. One argument is the center location (x,y). Next argument is axes lengths (major axis length, minor axis length). ``angle`` is the angle of rotation of ellipse in anti-clockwise direction. ``startAngle`` and ``endAngle`` denotes the starting and ending of ellipse arc measured in clockwise direction from major axis. i.e. giving values 0 and 360 gives the full ellipse. For more details, check the documentation of **cv2.ellipse()**. Below example draws a half ellipse at the center of the image.
 ::
 
-    img = cv2.ellipse(img,(256,256),(100,50),0,0,180,255,-1)
+    cv2.ellipse(img,(256,256),(100,50),0,0,180,255,-1)
 
 
 Drawing Polygon
@@ -65,7 +65,7 @@ To draw a polygon, first you need coordinates of vertices. Make those points int
 
     pts = np.array([[10,5],[20,30],[70,20],[50,10]], np.int32)
     pts = pts.reshape((-1,1,2))
-    img = cv2.polylines(img,[pts],True,(0,255,255))
+    cv2.polylines(img,[pts],True,(0,255,255))
 
 .. Note:: If third argument is ``False``, you will get a polylines joining all the points, not a closed shape.
 
@@ -103,4 +103,4 @@ Additional Resources
 
 Exercises
 ==============
-#. Try to create the logo of OpenCV using drawing functions available in OpenCV
+#. Try to create the logo of OpenCV using drawing functions available in OpenCV.