From 8bb3863f529e381bc67e477a84c2f451e5cd1c2d Mon Sep 17 00:00:00 2001 From: Suleyman TURKMEN Date: Sat, 5 Aug 2017 21:55:33 +0300 Subject: [PATCH] New example - warpPerspective_demo.cpp An example program shows using cv::findHomography and cv::warpPerspective for image warping --- modules/imgproc/include/opencv2/imgproc.hpp | 3 + samples/cpp/warpPerspective_demo.cpp | 181 ++++++++++++++++++++ 2 files changed, 184 insertions(+) create mode 100644 samples/cpp/warpPerspective_demo.cpp diff --git a/modules/imgproc/include/opencv2/imgproc.hpp b/modules/imgproc/include/opencv2/imgproc.hpp index 1c86adb17c..b59398e0c6 100644 --- a/modules/imgproc/include/opencv2/imgproc.hpp +++ b/modules/imgproc/include/opencv2/imgproc.hpp @@ -2264,6 +2264,9 @@ CV_EXPORTS_W void warpAffine( InputArray src, OutputArray dst, int borderMode = BORDER_CONSTANT, const Scalar& borderValue = Scalar()); +/** @example warpPerspective_demo.cpp +An example program shows using cv::findHomography and cv::warpPerspective for image warping + */ /** @brief Applies a perspective transformation to an image. The function warpPerspective transforms the source image using the specified matrix: diff --git a/samples/cpp/warpPerspective_demo.cpp b/samples/cpp/warpPerspective_demo.cpp new file mode 100644 index 0000000000..35bf87dfd9 --- /dev/null +++ b/samples/cpp/warpPerspective_demo.cpp @@ -0,0 +1,181 @@ +/** +@file warpPerspective_demo.cpp +@brief a demo program shows how perspective transformation applied on an image +@based on a sample code http://study.marearts.com/2015/03/image-warping-using-opencv.html +@modified by Suleyman TURKMEN +*/ + +#include "opencv2/imgproc.hpp" +#include "opencv2/imgcodecs.hpp" +#include "opencv2/highgui.hpp" +#include "opencv2/calib3d.hpp" +#include + +using namespace std; +using namespace cv; + +static void help(char** argv) +{ + // print a welcome message, and the OpenCV version + cout << "\nThis is a demo program shows how perspective transformation applied on an image, \n" + "Using OpenCV version " << CV_VERSION << endl; + + cout << "\nUsage:\n" << argv[0] << " [image_name -- Default ../data/right.jpg]\n" << endl; + + cout << "\nHot keys: \n" + "\tESC, q - quit the program\n" + "\tr - change order of points to rotate transformation\n" + "\tc - delete selected points\n" + "\ti - change order of points to invers transformation \n" + "\nUse your mouse to select a point and move it to see transformation changes" << endl; +} + +static void onMouse(int event, int x, int y, int, void*); +Mat warping(Mat image, Size warped_image_size, vector< Point2f> srcPoints, vector< Point2f> dstPoints); + +String windowTitle = "Perspective Transformation Demo"; +String labels[4] = { "TL","TR","BR","BL" }; +vector< Point2f> roi_corners; +vector< Point2f> dst_corners(4); +int roiIndex = 0; +bool dragging; +int selected_corner_index = 0; +bool validation_needed = true; + +int main(int argc, char** argv) +{ + help(argv); + CommandLineParser parser(argc, argv, "{@input| ../data/right.jpg |}"); + + string filename = parser.get("@input"); + Mat original_image = imread( filename ); + Mat image; + + float original_image_cols = (float)original_image.cols; + float original_image_rows = (float)original_image.rows; + roi_corners.push_back(Point2f( (float)(original_image_cols / 1.70), (float)(original_image_rows / 4.20) )); + roi_corners.push_back(Point2f( (float)(original_image.cols / 1.15), (float)(original_image.rows / 3.32) )); + roi_corners.push_back(Point2f( (float)(original_image.cols / 1.33), (float)(original_image.rows / 1.10) )); + roi_corners.push_back(Point2f( (float)(original_image.cols / 1.93), (float)(original_image.rows / 1.36) )); + + namedWindow(windowTitle, WINDOW_NORMAL); + namedWindow("Warped Image", WINDOW_AUTOSIZE); + moveWindow("Warped Image", 20, 20); + moveWindow(windowTitle, 330, 20); + + setMouseCallback(windowTitle, onMouse, 0); + + bool endProgram = false; + while (!endProgram) + { + if ( validation_needed & (roi_corners.size() < 4) ) + { + validation_needed = false; + image = original_image.clone(); + + for (size_t i = 0; i < roi_corners.size(); ++i) + { + circle( image, roi_corners[i], 5, Scalar(0, 255, 0), 3 ); + + if( i > 0 ) + { + line(image, roi_corners[i-1], roi_corners[(i)], Scalar(0, 0, 255), 2); + circle(image, roi_corners[i], 5, Scalar(0, 255, 0), 3); + putText(image, labels[i].c_str(), roi_corners[i], QT_FONT_NORMAL, 0.8, Scalar(255, 0, 0), 2); + } + } + imshow( windowTitle, image ); + } + + if ( validation_needed & ( roi_corners.size() == 4 )) + { + image = original_image.clone(); + for ( int i = 0; i < 4; ++i ) + { + line(image, roi_corners[i], roi_corners[(i + 1) % 4], Scalar(0, 0, 255), 2); + circle(image, roi_corners[i], 5, Scalar(0, 255, 0), 3); + putText(image, labels[i].c_str(), roi_corners[i], QT_FONT_NORMAL, 0.8, Scalar(255, 0, 0), 2); + } + + imshow( windowTitle, image ); + + dst_corners[0].x = 0; + dst_corners[0].y = 0; + dst_corners[1].x = (float)std::max(norm(roi_corners[0] - roi_corners[1]), norm(roi_corners[2] - roi_corners[3])); + dst_corners[1].y = 0; + dst_corners[2].x = (float)std::max(norm(roi_corners[0] - roi_corners[1]), norm(roi_corners[2] - roi_corners[3])); + dst_corners[2].y = (float)std::max(norm(roi_corners[1] - roi_corners[2]), norm(roi_corners[3] - roi_corners[0])); + dst_corners[3].x = 0; + dst_corners[3].y = (float)std::max(norm(roi_corners[1] - roi_corners[2]), norm(roi_corners[3] - roi_corners[0])); + + Size warped_image_size = Size(cvRound(dst_corners[2].x), cvRound(dst_corners[2].y)); + + Mat H = findHomography(roi_corners, dst_corners); //get homography + + Mat warped_image; + warpPerspective(original_image, warped_image, H, warped_image_size); // do perspective transformation + + imshow("Warped Image", warped_image); + } + + char c = (char)waitKey( 10 ); + + if ((c == 'q') | (c == 'Q') | (c == 27)) + { + endProgram = true; + } + + if ((c == 'c') | (c == 'C')) + { + roi_corners.clear(); + } + + if ((c == 'r') | (c == 'R')) + { + roi_corners.push_back(roi_corners[0]); + roi_corners.erase(roi_corners.begin()); + } + + if ((c == 'i') | (c == 'I')) + { + swap(roi_corners[0], roi_corners[1]); + swap(roi_corners[2], roi_corners[3]); + } + } + return 0; +} + +static void onMouse(int event, int x, int y, int, void*) +{ + // Action when left button is pressed + if (roi_corners.size() == 4) + { + for (int i = 0; i < 4; ++i) + { + if ((event == EVENT_LBUTTONDOWN) & ((abs(roi_corners[i].x - x) < 10)) & (abs(roi_corners[i].y - y) < 10)) + { + selected_corner_index = i; + dragging = true; + } + } + } + else if ( event == EVENT_LBUTTONDOWN ) + { + roi_corners.push_back( Point2f( (float) x, (float) y ) ); + validation_needed = true; + } + + // Action when left button is released + if (event == EVENT_LBUTTONUP) + { + dragging = false; + } + + // Action when left button is pressed and mouse has moved over the window + if ((event == EVENT_MOUSEMOVE) && dragging) + { + roi_corners[selected_corner_index].x = (float) x; + roi_corners[selected_corner_index].y = (float) y; + validation_needed = true; + } +}