Save Image to Specified File using OpenCV

While working with image processing, we might need to save an intermediate image or final resulting image to a specified file.

OpenCV provides the imwrite function that allows to save an image to a file. Image format is determined using filename extension.

import cv2

img = cv2.imread('test.jpg')
grayImg = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

cv2.imwrite('gray.jpg', grayImg)

#include <opencv2/opencv.hpp>

using namespace cv;

int main()
{
    Mat img = imread("test.jpg");
    Mat grayImg;
    cvtColor(img, grayImg, COLOR_BGR2GRAY);

    imwrite("gray.jpg", grayImg);

    return 0;
}

package app;

import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.imgproc.Imgproc;

public class Main
{
    static { System.loadLibrary(Core.NATIVE_LIBRARY_NAME); }

    public static void main(String[] args)
    {
        Mat img = Imgcodecs.imread("test.jpg");
        Mat grayImg = new Mat();
        Imgproc.cvtColor(img, grayImg, Imgproc.COLOR_BGR2GRAY);

        Imgcodecs.imwrite("gray.jpg", grayImg);

        System.exit(0);
    }
}