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Tutorial Make Border
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tribta
@@ -1,12 +1,15 @@
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Adding borders to your images {#tutorial_copyMakeBorder}
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=============================
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@prev_tutorial{tutorial_filter_2d}
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@next_tutorial{tutorial_sobel_derivatives}
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Goal
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----
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In this tutorial you will learn how to:
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- Use the OpenCV function @ref cv::copyMakeBorder to set the borders (extra padding to your
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- Use the OpenCV function **copyMakeBorder()** to set the borders (extra padding to your
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image).
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Theory
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@@ -30,10 +33,7 @@ Theory
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This will be seen more clearly in the Code section.
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Code
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----
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-# **What does this program do?**
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- **What does this program do?**
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- Load an image
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- Let the user choose what kind of padding use in the input image. There are two options:
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@@ -45,38 +45,153 @@ Code
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The user chooses either option by pressing 'c' (constant) or 'r' (replicate)
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- The program finishes when the user presses 'ESC'
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-# The tutorial code's is shown lines below. You can also download it from
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[here](https://github.com/opencv/opencv/tree/master/samples/cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp)
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@include samples/cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp
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Code
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----
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The tutorial code's is shown lines below.
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@add_toggle_cpp
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You can also download it from
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[here](https://raw.githubusercontent.com/opencv/opencv/master/samples/cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp)
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@include samples/cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp
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@end_toggle
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@add_toggle_java
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You can also download it from
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[here](https://raw.githubusercontent.com/opencv/opencv/master/samples/java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java)
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@include samples/java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java
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@end_toggle
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@add_toggle_python
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You can also download it from
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[here](https://raw.githubusercontent.com/opencv/opencv/master/samples/python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py)
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@include samples/python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py
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@end_toggle
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Explanation
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-----------
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-# First we declare the variables we are going to use:
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp variables
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#### Declare the variables
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Especial attention deserves the variable *rng* which is a random number generator. We use it to
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generate the random border color, as we will see soon.
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First we declare the variables we are going to use:
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-# As usual we load our source image *src*:
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp load
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp variables
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@end_toggle
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-# After giving a short intro of how to use the program, we create a window:
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp create_window
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-# Now we initialize the argument that defines the size of the borders (*top*, *bottom*, *left* and
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*right*). We give them a value of 5% the size of *src*.
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp init_arguments
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-# The program runs in a **for** loop. If the user presses 'c' or 'r', the *borderType* variable
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takes the value of *BORDER_CONSTANT* or *BORDER_REPLICATE* respectively:
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp check_keypress
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-# In each iteration (after 0.5 seconds), the variable *value* is updated...
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp update_value
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with a random value generated by the **RNG** variable *rng*. This value is a number picked
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randomly in the range \f$[0,255]\f$
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java variables
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@end_toggle
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-# Finally, we call the function @ref cv::copyMakeBorder to apply the respective padding:
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp copymakeborder
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The arguments are:
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py variables
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@end_toggle
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Especial attention deserves the variable *rng* which is a random number generator. We use it to
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generate the random border color, as we will see soon.
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#### Load an image
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As usual we load our source image *src*:
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp load
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java load
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py load
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@end_toggle
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#### Create a window
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After giving a short intro of how to use the program, we create a window:
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp create_window
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java create_window
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py create_window
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@end_toggle
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#### Initialize arguments
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Now we initialize the argument that defines the size of the borders (*top*, *bottom*, *left* and
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*right*). We give them a value of 5% the size of *src*.
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp init_arguments
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java init_arguments
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py init_arguments
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@end_toggle
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#### Loop
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The program runs in an infinite loop while the key **ESC** isn't pressed.
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If the user presses '**c**' or '**r**', the *borderType* variable
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takes the value of *BORDER_CONSTANT* or *BORDER_REPLICATE* respectively:
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp check_keypress
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java check_keypress
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py check_keypress
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@end_toggle
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#### Random color
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In each iteration (after 0.5 seconds), the random border color (*value*) is updated...
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp update_value
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java update_value
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py update_value
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@end_toggle
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This value is a set of three numbers picked randomly in the range \f$[0,255]\f$.
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#### Form a border around the image
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Finally, we call the function **copyMakeBorder()** to apply the respective padding:
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp copymakeborder
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java copymakeborder
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py copymakeborder
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@end_toggle
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- The arguments are:
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-# *src*: Source image
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-# *dst*: Destination image
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@@ -87,8 +202,21 @@ Explanation
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-# *value*: If *borderType* is *BORDER_CONSTANT*, this is the value used to fill the border
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pixels.
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-# We display our output image in the image created previously
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp display
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#### Display the results
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We display our output image in the image created previously
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@add_toggle_cpp
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@snippet cpp/tutorial_code/ImgTrans/copyMakeBorder_demo.cpp display
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@end_toggle
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@add_toggle_java
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@snippet java/tutorial_code/ImgTrans/MakeBorder/CopyMakeBorder.java display
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@end_toggle
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@add_toggle_python
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@snippet python/tutorial_code/ImgTrans/MakeBorder/copy_make_border.py display
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@end_toggle
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Results
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-------
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@@ -87,6 +87,8 @@ In this section you will learn about the image processing (manipulation) functio
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- @subpage tutorial_copyMakeBorder
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*Languages:* C++, Java, Python
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*Compatibility:* \> OpenCV 2.0
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*Author:* Ana Huamán
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