本文实例为大家分享了OpenCV选择图像中矩形区域并保存的具体代码，供大家参考，具体内容如下

根据《Learning OpenCV》中的example4.1改写:

// An example program in which the// user can draw boxes on the screen.////#include <cv.h>//#include <highgui.h>#include "opencv2/imgproc/imgproc.hpp"#include "opencv2/highgui/highgui.hpp"using namespace cv;// Define our callback which we will install for// mouse events.//void my_mouse_callback( int event, int x, int y, int flags, void* param); CvRect box;bool drawing_box = false;bool isRectDrawn = false; // A litte subroutine to draw a box onto an image_copyvoid draw_box( IplImage* img, CvRect rect ) { cvRectangle ( img, cvPoint(box.x,box.y), cvPoint(box.x+box.width,box.y+box.height), cvScalar(0x00,0x00,0xff) );} void draw_box_green( IplImage* img, CvRect rect ) { cvRectangle ( img, cvPoint(box.x,box.y), cvPoint(box.x+box.width,box.y+box.height), cvScalar(0x00,0xff,0x00) );} int main( int argc, char* argv[] ) { box = cvRect(-1,-1,0,0); IplImage* image_input = cvLoadImage(argv[1]); IplImage* image = cvCloneImage( image_input ); IplImage* image_copy = cvCloneImage( image ); IplImage* temp = cvCloneImage( image_copy ); cvNamedWindow( "Box Example" ); // Here is the crucial moment that we actually install // the callback. Note that we set the value ‘param' to // be the image_copy we are working with so that the callback // will have the image_copy to edit. // cvSetMouseCallback( "Box Example", my_mouse_callback, (void*) image_copy ); // The main program loop. Here we copy the working image_copy // to the ‘temp' image_copy, and if the user is drawing, then // put the currently contemplated box onto that temp image_copy. // display the temp image_copy, and wait 15ms for a keystroke, // then repeat… // while( 1 ) { //cvCopyImage( image_copy, temp ); cvCopy( image_copy, temp ); if( drawing_box ) draw_box( temp, box ); cvShowImage( "Box Example", temp ); //if( cvWaitKey( 15 )==27 ) break; int key = cvWaitKey( 15 ); if(key == 27) break; if(isRectDrawn){ if(key == 's' || key == 'S'){ // draw green box draw_box_green( image_copy, box ); cvCopy( image_copy, image ); // save roi image static int index = 0; char save_image_name[128]; sprintf(save_image_name, "rect_%d.jpg", index++); cvSetImageROI(image_input, box); cvSaveImage(save_image_name, image_input); cvResetImageROI(image_input); isRectDrawn = false; } if(key == 'q' || key == 'Q'){ cvCopy( image, image_copy ); isRectDrawn = false; } } } // Be tidy // cvReleaseImage( &image_copy ); cvReleaseImage( &temp ); cvDestroyWindow( "Box Example" );} // This is our mouse callback. If the user// presses the left button, we start a box.// when the user releases that button, then we// add the box to the current image_copy. When the// mouse is dragged (with the button down) we// resize the box.//void my_mouse_callback(int event, int x, int y, int flags, void* param) { IplImage* image_copy = (IplImage*) param; switch( event ) { case CV_EVENT_MOUSEMOVE: { if( drawing_box ) { box.width = x-box.x; box.height = y-box.y; } } break; case CV_EVENT_LBUTTONDOWN: { drawing_box = true; box = cvRect(x, y, 0, 0); } break; case CV_EVENT_LBUTTONUP: { drawing_box = false; isRectDrawn = true; if(box.width<0) { box.x+=box.width; box.width *=-1; } if(box.height<0) { box.y+=box.height; box.height*=-1; } draw_box(image_copy, box); } break; }}

使用方法：

载入图像后，用鼠标在图像上点击确定矩形起始点，拖动鼠标画矩形，抬起鼠标键时会画出一个红色矩形区域。按下s或S键，红色矩形变成绿色，并保存这个ROI区域。如果按下q或Q键，将会取消这次选择，红色矩形框消失。可以连续选取多个区域。按ESC键退出程序。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。