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Merge pull request #186 from vpisarev:doc_fixes_master
This commit is contained in:
Andrey Kamaev
OpenCV Buildbot
commit
61a40ddff8
@ -31,15 +31,15 @@ Point
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.. code-block:: cpp
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Point pt;
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pt.x = 10;
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pt.y = 8;
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Point pt;
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pt.x = 10;
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pt.y = 8;
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or
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.. code-block:: cpp
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Point pt = Point(10, 8);
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Point pt = Point(10, 8);
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Scalar
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-------
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@ -49,7 +49,7 @@ Scalar
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.. code-block:: cpp
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Scalar( a, b, c )
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Scalar( a, b, c )
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We would be defining a RGB color such as: *Red = c*, *Green = b* and *Blue = a*
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@ -65,51 +65,51 @@ Explanation
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.. code-block:: cpp
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/// Windows names
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char atom_window[] = "Drawing 1: Atom";
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char rook_window[] = "Drawing 2: Rook";
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/// Windows names
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char atom_window[] = "Drawing 1: Atom";
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char rook_window[] = "Drawing 2: Rook";
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/// Create black empty images
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Mat atom_image = Mat::zeros( w, w, CV_8UC3 );
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Mat rook_image = Mat::zeros( w, w, CV_8UC3 );
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/// Create black empty images
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Mat atom_image = Mat::zeros( w, w, CV_8UC3 );
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Mat rook_image = Mat::zeros( w, w, CV_8UC3 );
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#. We created functions to draw different geometric shapes. For instance, to draw the atom we used *MyEllipse* and *MyFilledCircle*:
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.. code-block:: cpp
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/// 1. Draw a simple atom:
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/// 1. Draw a simple atom:
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/// 1.a. Creating ellipses
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MyEllipse( atom_image, 90 );
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MyEllipse( atom_image, 0 );
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MyEllipse( atom_image, 45 );
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MyEllipse( atom_image, -45 );
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/// 1.a. Creating ellipses
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MyEllipse( atom_image, 90 );
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MyEllipse( atom_image, 0 );
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MyEllipse( atom_image, 45 );
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MyEllipse( atom_image, -45 );
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/// 1.b. Creating circles
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MyFilledCircle( atom_image, Point( w/2.0, w/2.0) );
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/// 1.b. Creating circles
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MyFilledCircle( atom_image, Point( w/2.0, w/2.0) );
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#. And to draw the rook we employed *MyLine*, *rectangle* and a *MyPolygon*:
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.. code-block:: cpp
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/// 2. Draw a rook
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/// 2. Draw a rook
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/// 2.a. Create a convex polygon
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MyPolygon( rook_image );
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/// 2.a. Create a convex polygon
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MyPolygon( rook_image );
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/// 2.b. Creating rectangles
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rectangle( rook_image,
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Point( 0, 7*w/8.0 ),
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Point( w, w),
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Scalar( 0, 255, 255 ),
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-1,
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8 );
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/// 2.b. Creating rectangles
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rectangle( rook_image,
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Point( 0, 7*w/8.0 ),
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Point( w, w),
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Scalar( 0, 255, 255 ),
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-1,
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8 );
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/// 2.c. Create a few lines
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MyLine( rook_image, Point( 0, 15*w/16 ), Point( w, 15*w/16 ) );
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MyLine( rook_image, Point( w/4, 7*w/8 ), Point( w/4, w ) );
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MyLine( rook_image, Point( w/2, 7*w/8 ), Point( w/2, w ) );
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MyLine( rook_image, Point( 3*w/4, 7*w/8 ), Point( 3*w/4, w ) );
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/// 2.c. Create a few lines
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MyLine( rook_image, Point( 0, 15*w/16 ), Point( w, 15*w/16 ) );
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MyLine( rook_image, Point( w/4, 7*w/8 ), Point( w/4, w ) );
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MyLine( rook_image, Point( w/2, 7*w/8 ), Point( w/2, w ) );
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MyLine( rook_image, Point( 3*w/4, 7*w/8 ), Point( 3*w/4, w ) );
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#. Let's check what is inside each of these functions:
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@ -117,17 +117,15 @@ Explanation
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.. code-block:: cpp
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void MyLine( Mat img, Point start, Point end )
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{
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int thickness = 2;
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int lineType = 8;
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line( img,
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start,
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end,
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Scalar( 0, 0, 0 ),
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thickness,
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lineType );
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}
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void MyLine( Mat img, Point start, Point end )
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{
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int thickness = 2;
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int lineType = 8;
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line( img, start, end,
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Scalar( 0, 0, 0 ),
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thickness,
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lineType );
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}
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As we can see, *MyLine* just call the function :line:`line <>`, which does the following:
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@ -143,32 +141,32 @@ Explanation
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.. code-block:: cpp
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void MyEllipse( Mat img, double angle )
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{
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int thickness = 2;
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int lineType = 8;
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void MyEllipse( Mat img, double angle )
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{
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int thickness = 2;
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int lineType = 8;
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ellipse( img,
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Point( w/2.0, w/2.0 ),
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Size( w/4.0, w/16.0 ),
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angle,
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0,
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360,
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Scalar( 255, 0, 0 ),
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thickness,
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lineType );
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}
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ellipse( img,
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Point( w/2.0, w/2.0 ),
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Size( w/4.0, w/16.0 ),
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angle,
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0,
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360,
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Scalar( 255, 0, 0 ),
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thickness,
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lineType );
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}
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From the code above, we can observe that the function :ellipse:`ellipse <>` draws an ellipse such that:
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.. container:: enumeratevisibleitemswithsquare
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* The ellipse is displayed in the image **img**
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* The ellipse center is located in the point **(w/2.0, w/2.0)** and is enclosed in a box of size **(w/4.0, w/16.0)**
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* The ellipse is rotated **angle** degrees
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* The ellipse extends an arc between **0** and **360** degrees
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* The color of the figure will be **Scalar( 255, 255, 0)** which means blue in RGB value.
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* The ellipse's **thickness** is 2.
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* The ellipse is displayed in the image **img**
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* The ellipse center is located in the point **(w/2.0, w/2.0)** and is enclosed in a box of size **(w/4.0, w/16.0)**
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* The ellipse is rotated **angle** degrees
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* The ellipse extends an arc between **0** and **360** degrees
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* The color of the figure will be **Scalar( 255, 255, 0)** which means blue in RGB value.
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* The ellipse's **thickness** is 2.
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* *MyFilledCircle*
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@ -176,17 +174,17 @@ Explanation
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.. code-block:: cpp
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void MyFilledCircle( Mat img, Point center )
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{
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int thickness = -1;
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int lineType = 8;
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{
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int thickness = -1;
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int lineType = 8;
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circle( img,
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center,
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w/32.0,
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Scalar( 0, 0, 255 ),
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thickness,
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lineType );
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}
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circle( img,
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center,
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w/32.0,
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Scalar( 0, 0, 255 ),
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thickness,
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lineType );
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}
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Similar to the ellipse function, we can observe that *circle* receives as arguments:
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@ -202,43 +200,43 @@ Explanation
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.. code-block:: cpp
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void MyPolygon( Mat img )
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{
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int lineType = 8;
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void MyPolygon( Mat img )
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{
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int lineType = 8;
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/** Create some points */
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Point rook_points[1][20];
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rook_points[0][0] = Point( w/4.0, 7*w/8.0 );
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rook_points[0][1] = Point( 3*w/4.0, 7*w/8.0 );
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rook_points[0][2] = Point( 3*w/4.0, 13*w/16.0 );
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rook_points[0][3] = Point( 11*w/16.0, 13*w/16.0 );
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rook_points[0][4] = Point( 19*w/32.0, 3*w/8.0 );
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rook_points[0][5] = Point( 3*w/4.0, 3*w/8.0 );
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rook_points[0][6] = Point( 3*w/4.0, w/8.0 );
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rook_points[0][7] = Point( 26*w/40.0, w/8.0 );
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rook_points[0][8] = Point( 26*w/40.0, w/4.0 );
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rook_points[0][9] = Point( 22*w/40.0, w/4.0 );
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rook_points[0][10] = Point( 22*w/40.0, w/8.0 );
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rook_points[0][11] = Point( 18*w/40.0, w/8.0 );
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rook_points[0][12] = Point( 18*w/40.0, w/4.0 );
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rook_points[0][13] = Point( 14*w/40.0, w/4.0 );
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rook_points[0][14] = Point( 14*w/40.0, w/8.0 );
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rook_points[0][15] = Point( w/4.0, w/8.0 );
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rook_points[0][16] = Point( w/4.0, 3*w/8.0 );
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rook_points[0][17] = Point( 13*w/32.0, 3*w/8.0 );
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rook_points[0][18] = Point( 5*w/16.0, 13*w/16.0 );
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rook_points[0][19] = Point( w/4.0, 13*w/16.0) ;
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/** Create some points */
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Point rook_points[1][20];
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rook_points[0][0] = Point( w/4.0, 7*w/8.0 );
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rook_points[0][1] = Point( 3*w/4.0, 7*w/8.0 );
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rook_points[0][2] = Point( 3*w/4.0, 13*w/16.0 );
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rook_points[0][3] = Point( 11*w/16.0, 13*w/16.0 );
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rook_points[0][4] = Point( 19*w/32.0, 3*w/8.0 );
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rook_points[0][5] = Point( 3*w/4.0, 3*w/8.0 );
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rook_points[0][6] = Point( 3*w/4.0, w/8.0 );
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rook_points[0][7] = Point( 26*w/40.0, w/8.0 );
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rook_points[0][8] = Point( 26*w/40.0, w/4.0 );
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rook_points[0][9] = Point( 22*w/40.0, w/4.0 );
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rook_points[0][10] = Point( 22*w/40.0, w/8.0 );
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rook_points[0][11] = Point( 18*w/40.0, w/8.0 );
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rook_points[0][12] = Point( 18*w/40.0, w/4.0 );
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rook_points[0][13] = Point( 14*w/40.0, w/4.0 );
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rook_points[0][14] = Point( 14*w/40.0, w/8.0 );
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rook_points[0][15] = Point( w/4.0, w/8.0 );
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rook_points[0][16] = Point( w/4.0, 3*w/8.0 );
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rook_points[0][17] = Point( 13*w/32.0, 3*w/8.0 );
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rook_points[0][18] = Point( 5*w/16.0, 13*w/16.0 );
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rook_points[0][19] = Point( w/4.0, 13*w/16.0) ;
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const Point* ppt[1] = { rook_points[0] };
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int npt[] = { 20 };
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const Point* ppt[1] = { rook_points[0] };
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int npt[] = { 20 };
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fillPoly( img,
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ppt,
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npt,
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1,
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Scalar( 255, 255, 255 ),
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lineType );
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}
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fillPoly( img,
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ppt,
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npt,
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1,
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Scalar( 255, 255, 255 ),
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lineType );
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}
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To draw a filled polygon we use the function :fill_poly:`fillPoly <>`. We note that:
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@ -254,12 +252,11 @@ Explanation
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.. code-block:: cpp
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rectangle( rook_image,
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Point( 0, 7*w/8.0 ),
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Point( w, w),
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Scalar( 0, 255, 255 ),
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-1,
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8 );
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rectangle( rook_image,
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Point( 0, 7*w/8.0 ),
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Point( w, w),
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Scalar( 0, 255, 255 ),
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-1, 8 );
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Finally we have the :rectangle:`rectangle <>` function (we did not create a special function for this guy). We note that:
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@ -11,17 +11,15 @@ In this tutorial you will learn how to:
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.. container:: enumeratevisibleitemswithsquare
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+ Access pixel values
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+ Initialize a matrix with zeros
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+ Learn what :saturate_cast:`saturate_cast <>` does and why it is useful
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+ Get some cool info about pixel transformations
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Theory
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=======
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.. note::
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The explanation below belongs to the book `Computer Vision: Algorithms and Applications <http://szeliski.org/Book/>`_ by Richard Szeliski
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Image Processing
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@ -38,7 +36,7 @@ Image Processing
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Pixel Transforms
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^^^^^^^^^^^^^^^^^
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-----------------
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.. container:: enumeratevisibleitemswithsquare
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@ -47,7 +45,7 @@ Pixel Transforms
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* Examples of such operators include *brightness and contrast adjustments* as well as color correction and transformations.
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Brightness and contrast adjustments
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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------------------------------------
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.. container:: enumeratevisibleitemswithsquare
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@ -70,9 +68,7 @@ Brightness and contrast adjustments
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Code
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=====
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.. container:: enumeratevisibleitemswithsquare
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* The following code performs the operation :math:`g(i,j) = \alpha \cdot f(i,j) + \beta` :
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* The following code performs the operation :math:`g(i,j) = \alpha \cdot f(i,j) + \beta` :
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.. code-block:: cpp
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@ -87,38 +83,37 @@ Code
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int main( int argc, char** argv )
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{
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/// Read image given by user
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Mat image = imread( argv[1] );
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Mat new_image = Mat::zeros( image.size(), image.type() );
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/// Read image given by user
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Mat image = imread( argv[1] );
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Mat new_image = Mat::zeros( image.size(), image.type() );
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/// Initialize values
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std::cout<<" Basic Linear Transforms "<<std::endl;
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std::cout<<"-------------------------"<<std::endl;
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std::cout<<"* Enter the alpha value [1.0-3.0]: ";std::cin>>alpha;
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std::cout<<"* Enter the beta value [0-100]: "; std::cin>>beta;
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/// Initialize values
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std::cout<<" Basic Linear Transforms "<<std::endl;
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std::cout<<"-------------------------"<<std::endl;
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std::cout<<"* Enter the alpha value [1.0-3.0]: ";std::cin>>alpha;
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std::cout<<"* Enter the beta value [0-100]: "; std::cin>>beta;
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/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
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for( int y = 0; y < image.rows; y++ )
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{ for( int x = 0; x < image.cols; x++ )
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{ for( int c = 0; c < 3; c++ )
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{
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new_image.at<Vec3b>(y,x)[c] =
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saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
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}
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}
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/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
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for( int y = 0; y < image.rows; y++ ) {
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for( int x = 0; x < image.cols; x++ ) {
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for( int c = 0; c < 3; c++ ) {
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new_image.at<Vec3b>(y,x)[c] =
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saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
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}
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}
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}
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/// Create Windows
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namedWindow("Original Image", 1);
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namedWindow("New Image", 1);
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/// Create Windows
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namedWindow("Original Image", 1);
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namedWindow("New Image", 1);
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/// Show stuff
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imshow("Original Image", image);
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imshow("New Image", new_image);
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/// Show stuff
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imshow("Original Image", image);
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imshow("New Image", new_image);
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/// Wait until user press some key
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waitKey();
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return 0;
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/// Wait until user press some key
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waitKey();
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return 0;
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}
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Explanation
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||||
@ -155,13 +150,14 @@ Explanation
|
||||
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||||
.. code-block:: cpp
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||||
|
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for( int y = 0; y < image.rows; y++ )
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{ for( int x = 0; x < image.cols; x++ )
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{ for( int c = 0; c < 3; c++ )
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{ new_image.at<Vec3b>(y,x)[c] =
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saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta ); }
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}
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}
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for( int y = 0; y < image.rows; y++ ) {
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for( int x = 0; x < image.cols; x++ ) {
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for( int c = 0; c < 3; c++ ) {
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new_image.at<Vec3b>(y,x)[c] =
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saturate_cast<uchar>( alpha*( image.at<Vec3b>(y,x)[c] ) + beta );
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||||
}
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||||
}
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}
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Notice the following:
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||||
@ -209,6 +205,6 @@ Result
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||||
|
||||
* We get this:
|
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|
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.. image:: images/Basic_Linear_Transform_Tutorial_Result_0.jpg
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:alt: Basic Linear Transform - Final Result
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:align: center
|
||||
.. image:: images/Basic_Linear_Transform_Tutorial_Result_0.jpg
|
||||
:alt: Basic Linear Transform - Final Result
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:align: center
|
||||
|
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@ -39,7 +39,7 @@ Morphological Operations
|
||||
:align: center
|
||||
|
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Dilation
|
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^^^^^^^^^
|
||||
~~~~~~~~
|
||||
|
||||
* This operations consists of convoluting an image :math:`A` with some kernel (:math:`B`), which can have any shape or size, usually a square or circle.
|
||||
|
||||
@ -54,7 +54,7 @@ Dilation
|
||||
The background (bright) dilates around the black regions of the letter.
|
||||
|
||||
Erosion
|
||||
^^^^^^^^
|
||||
~~~~~~~
|
||||
|
||||
* This operation is the sister of dilation. What this does is to compute a local minimum over the area of the kernel.
|
||||
|
||||
@ -216,17 +216,17 @@ Explanation
|
||||
|
||||
.. code-block:: cpp
|
||||
|
||||
Mat element = getStructuringElement( erosion_type,
|
||||
Size( 2*erosion_size + 1, 2*erosion_size+1 ),
|
||||
Point( erosion_size, erosion_size ) );
|
||||
Mat element = getStructuringElement( erosion_type,
|
||||
Size( 2*erosion_size + 1, 2*erosion_size+1 ),
|
||||
Point( erosion_size, erosion_size ) );
|
||||
|
||||
We can choose any of three shapes for our kernel:
|
||||
|
||||
.. container:: enumeratevisibleitemswithsquare
|
||||
|
||||
+ Rectangular box: MORPH_RECT
|
||||
+ Cross: MORPH_CROSS
|
||||
+ Ellipse: MORPH_ELLIPSE
|
||||
+ Rectangular box: MORPH_RECT
|
||||
+ Cross: MORPH_CROSS
|
||||
+ Ellipse: MORPH_ELLIPSE
|
||||
|
||||
Then, we just have to specify the size of our kernel and the *anchor point*. If not specified, it is assumed to be in the center.
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user