Resize an image to a square but keep aspect ratio c++ opencv

Question

Is there a way of resizing images of any shape or size to say [500x500] but have the image\'s aspect ratio be maintained, levaing the empty space be filled with whi

Answer 1

You can create another image of the square size you wish, then put your image in the middle of the square image. Something like this:

#include 
#include 
#include "opencv2/imgproc/imgproc.hpp"

int main(int argc, char *argv[])
{
    // read an image
    cv::Mat image1= cv::imread("/home/hdang/Desktop/colorCode.png");

    //resize it
    cv::Size newSize = cv::Size(image1.cols/2,image1.rows/2);
    cv::resize(image1, image1, newSize, 0, 0, cv::INTER_LINEAR);

    //create the square container
    int dstWidth = 500;
    int dstHeight = 500;
    cv::Mat dst = cv::Mat(dstHeight, dstWidth, CV_8UC3, cv::Scalar(0,0,0));

    //Put the image into the container, roi is the new position
    cv::Rect roi(cv::Rect(0,dst.rows*0.25,image1.cols,image1.rows));
    cv::Mat targetROI = dst(roi);
    image1.copyTo(targetROI);

    //View the result
    cv::namedWindow("OpenCV Window");
    cv::imshow("OpenCV Window", dst);

    // wait key for 5000 ms
    cv::waitKey(5000);

    return 0;
}