Doxygen tutorials: cpp done
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@@ -21,6 +21,8 @@ Download the source code from
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Explanation
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-----------
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@dontinclude cpp/tutorial_code/introduction/display_image/display_image.cpp
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In OpenCV 2 we have multiple modules. Each one takes care of a different area or approach towards
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image processing. You could already observe this in the structure of the user guide of these
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tutorials itself. Before you use any of them you first need to include the header files where the
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@@ -31,36 +33,25 @@ You'll almost always end up using the:
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- *core* section, as here are defined the basic building blocks of the library
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- *highgui* module, as this contains the functions for input and output operations
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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1-6
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@until <string>
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We also include the *iostream* to facilitate console line output and input. To avoid data structure
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and function name conflicts with other libraries, OpenCV has its own namespace: *cv*. To avoid the
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need appending prior each of these the *cv::* keyword you can import the namespace in the whole file
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by using the lines:
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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8-9
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@line using namespace cv
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This is true for the STL library too (used for console I/O). Now, let's analyze the *main* function.
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We start up assuring that we acquire a valid image name argument from the command line. Otherwise
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take a picture by default: "HappyFish.jpg".
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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13-17
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@skip string
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@until }
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Then create a *Mat* object that will store the data of the loaded image.
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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19
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@skipline Mat
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Now we call the @ref cv::imread function which loads the image name specified by the first argument
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(*argv[1]*). The second argument specifies the format in what we want the image. This may be:
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@@ -69,10 +60,7 @@ Now we call the @ref cv::imread function which loads the image name specified by
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- IMREAD_GRAYSCALE ( 0) loads the image as an intensity one
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- IMREAD_COLOR (\>0) loads the image in the RGB format
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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20
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@skipline image = imread
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@note
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OpenCV offers support for the image formats Windows bitmap (bmp), portable image formats (pbm,
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@@ -94,30 +82,18 @@ the image it contains from a size point of view. It may be:
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would like the image to keep its aspect ratio (*WINDOW_KEEPRATIO*) or not
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(*WINDOW_FREERATIO*).
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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28
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@skipline namedWindow
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Finally, to update the content of the OpenCV window with a new image use the @ref cv::imshow
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function. Specify the OpenCV window name to update and the image to use during this operation:
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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29
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@skipline imshow
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Because we want our window to be displayed until the user presses a key (otherwise the program would
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end far too quickly), we use the @ref cv::waitKey function whose only parameter is just how long
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should it wait for a user input (measured in milliseconds). Zero means to wait forever.
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@includelineno cpp/tutorial_code/introduction/display_image/display_image.cpp
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lines
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31
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@skipline waitKey
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Result
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------
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@@ -130,11 +106,10 @@ Result
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@endcode
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- You should get a nice window as the one shown below:
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\htmlonly
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<div align="center">
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<iframe title="Introduction - Display an Image" width="560" height="349" src="http://www.youtube.com/embed/1OJEqpuaGc4?rel=0&loop=1" frameborder="0" allowfullscreen align="middle"></iframe>
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</div>
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\endhtmlonly
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