Merge pull request #7442 from catree:morphology_additional_information

doc/tutorials/imgproc/erosion_dilatation/erosion_dilatation.markdown

@@ -44,6 +44,14 @@ Morphological Operations
 
 The background (bright) dilates around the black regions of the letter.
 
+To better grasp the idea and avoid possible confusion, in this another example we have inverted the original
+image such as the object in white is now the letter. We have performed two dilatations with a rectangular
+structuring element of size `3x3`.
+
+![Left image: original image inverted, right image: resulting dilatation](images/Morphology_1_Tutorial_Theory_Dilatation_2.png)
+
+The dilatation makes the object in white bigger.
+
 ### Erosion
 
 -   This operation is the sister of dilation. What this does is to compute a local minimum over the
@@ -56,6 +64,13 @@ The background (bright) dilates around the black regions of the letter.
 
     ![](images/Morphology_1_Tutorial_Theory_Erosion.png)
 
+In the same manner, the corresponding image resulting of the erosion operation on the inverted original image (two erosions
+with a rectangular structuring element of size `3x3`):
+
+![Left image: original image inverted, right image: resulting erosion](images/Morphology_1_Tutorial_Theory_Erosion_2.png)
+
+The erosion makes the object in white smaller.
+
 Code
 ----
 

doc/tutorials/imgproc/opening_closing_hats/opening_closing_hats.markdown

@@ -24,7 +24,7 @@ In the previous tutorial we covered two basic Morphology operations:
 -   Dilation.
 
 Based on these two we can effectuate more sophisticated transformations to our images. Here we
-discuss briefly 05 operations offered by OpenCV:
+discuss briefly 5 operations offered by OpenCV:
 
 ### Opening
 
@@ -40,6 +40,11 @@ discuss briefly 05 operations offered by OpenCV:
 
     ![](images/Morphology_2_Tutorial_Theory_Opening.png)
 
+For the sake of clarity, we have performed the opening operation (`7x7` rectangular structuring element)
+on the same original image but inverted such as the object in white is now the letter.
+
+![Left image: original image inverted, right image: resulting opening](images/Morphology_2_Tutorial_Theory_Opening_2.png)
+
 ### Closing
 
 -   It is obtained by the dilation of an image followed by an erosion.
@@ -50,6 +55,10 @@ discuss briefly 05 operations offered by OpenCV:
 
     ![](images/Morphology_2_Tutorial_Theory_Closing.png)
 
+On the inverted image, we have performed the closing operation (`7x7` rectangular structuring element):
+
+![Left image: original image inverted, right image: resulting closing](images/Morphology_2_Tutorial_Theory_Closing_2.png)
+
 ### Morphological Gradient
 
 -   It is the difference between the dilation and the erosion of an image.