118 lines
3.0 KiB
ReStructuredText
118 lines
3.0 KiB
ReStructuredText
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.. _warp_affine:
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Affine Transformations
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**********************
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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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a. Use the OpenCV function :warp_affine:`warpAffine <>` to implement simple remapping routines.
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b. Use the OpenCV function :get_rotation_matrix_2d:`getRotationMatrix2D <>` to obtain a :math:`2 \times 3` rotation matrix
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Theory
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======
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Code
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====
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.. code-block:: cpp
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#include "opencv2/highgui/highgui.hpp"
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#include "opencv2/imgproc/imgproc.hpp"
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#include <iostream>
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#include <stdio.h>
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using namespace cv;
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using namespace std;
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/// Global variables
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char* source_window = "Source image";
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char* warp_window = "Warp";
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char* warp_rotate_window = "Warp + Rotate";
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/** @function main */
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int main( int argc, char** argv )
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{
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Point2f srcTri[3];
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Point2f dstTri[3];
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Mat rot_mat( 2, 3, CV_32FC1 );
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Mat warp_mat( 2, 3, CV_32FC1 );
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Mat src, warp_dst, warp_rotate_dst;
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/// Load the image
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src = imread( argv[1], 1 );
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/// Set the dst image the same type and size as src
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warp_dst = Mat::zeros( src.rows, src.cols, src.type() );
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/// Set your 3 points to calculate the Affine Transform
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srcTri[0] = Point2f( 0,0 );
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srcTri[1] = Point2f( src.cols - 1, 0 );
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srcTri[2] = Point2f( 0, src.rows - 1 );
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dstTri[0] = Point2f( src.cols*0.0, src.rows*0.33 );
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dstTri[1] = Point2f( src.cols*0.85, src.rows*0.25 );
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dstTri[2] = Point2f( src.cols*0.15, src.rows*0.7 );
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/// Get the Affine Transform
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warp_mat = getAffineTransform( srcTri, dstTri );
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/// Apply the Affine Transform just found to the src image
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warpAffine( src, warp_dst, warp_mat, warp_dst.size() );
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/** Rotating the image after Warp */
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/// Compute a rotation matrix with respect to the center of the image
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Point center = Point( warp_dst.cols/2, warp_dst.rows/2 );
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double angle = -50.0;
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double scale = 0.6;
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/// Get the rotation matrix with the specifications above
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rot_mat = getRotationMatrix2D( center, angle, scale );
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/// Rotate the warped image
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warpAffine( warp_dst, warp_rotate_dst, rot_mat, warp_dst.size() );
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/// Show what you got
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namedWindow( source_window, CV_WINDOW_AUTOSIZE );
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imshow( source_window, src );
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namedWindow( warp_window, CV_WINDOW_AUTOSIZE );
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imshow( warp_window, warp_dst );
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namedWindow( warp_rotate_window, CV_WINDOW_AUTOSIZE );
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imshow( warp_rotate_window, warp_rotate_dst );
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/// Wait until user exits the program
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waitKey(0);
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return 0;
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}
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Explanation
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===========
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Result
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======
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.. image:: images/Warp_Affine_Tutorial_Original_Image.jpg
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:alt: Original image
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:width: 250pt
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:align: center
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.. image:: images/Warp_Affine_Tutorial_Result_Warp.jpg
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:alt: Original image
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:width: 250pt
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:align: center
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.. image:: images/Warp_Affine_Tutorial_Result_Warp_Rotate.jpg
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:alt: Original image
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:width: 250pt
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:align: center
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