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  1. #1
    Join Date
    Jun 2021

    Picture Comparison Code Not Working Properly

    I am still very much a beginner in programming and am facing a problem with a Java code. I would be very thankful for suggestions and comments. The problem is as following:

    I found a Java code online that is designed to compare two pictures and highlight the differences between them. However, the way the code works is by using a loop that compares the RGB value of each pixel of the two pictures and highlights it in a certain color if the value is equal. This however results in a problem that even the slightest shift in camera angle or lighting conditions between the two pictures leads to a different RGB value of the pixels making the code highlight them as a difference even though the pictures are mostly identical. The code is written below and i have added the link to photos showing examples of the outcome of the code. What would you suggest i change in the code? Thank you for your help in advance.

    The code:

    import java.awt.image.BufferedImage;
        import javax.imageio.ImageIO; 
    public class PictureOverlayTest {
         * Four variables, three for the wanted BufferedImages, one String for the
         * Path of the third Image, which does not already exist.
        private BufferedImage image1;
        private BufferedImage image2;
        private BufferedImage image3;
        private String pathImage3;
        public PictureOverlayTest(String filePathAndName1, String filePathAndName2,
                String filePathAndName3) throws IOException {
             * Constructor in order to keep this method reusable and clean. Needs
             * three Strings. The paths and Filenames of all three images. Image 1
             * and 2 should exist already, Image 3 will be created if all
             * requirements are met. Constructor creates the first two buffered
             * images, sets all needed variables and starts the checkAndCompare()
             * method
            File file = new File(filePathAndName1);
            this.image1 =;
            file = new File(filePathAndName2);
            this.image2 =;
            this.pathImage3 = filePathAndName3;
        private void checkAndCompare() throws IOException {
             * This function creates the Color blue, compares the sizes of both
             * pictures and if they are the same, creates a third image. Then it
             * loops through the two images and compares each pixel. If the pixels
             * are the same, the third image gets a blue pixel at that point
            Color blue =;
            Color yellow = Color.yellow;
            if (image1.getHeight() == image2.getHeight()
                    && image1.getWidth() == image2.getWidth()) {
                image3 = new BufferedImage(image1.getWidth(), image1.getHeight(),
                for (int y = 0; y < image1.getHeight(); y++) {
                    for (int x = 0; x < image1.getWidth(); x++) {
                        int colorImage1 = image1.getRGB(x, y);
                        int colorImage2 = image2.getRGB(x, y);
                        if (colorImage1 == colorImage2) {
                            image3.setRGB(x, y, blue.getRGB());
                        } else {
                                  image3.setRGB(x, y, yellow.getRGB()); 
                            // Whatever Color you want. By default it is black.
                System.out.println("Message: Image comparison is done");
            } else {
                System.out.println("Error: Image dimensions do not match");
        private void savePicture3() throws IOException {
             * This method saves the created Image into a file onto your computer.
             * The if() statement is used to check if the file was successfully
             * created, in order to avoid unwanted errors. Keep in mind, that you
             * have to change the "bmp" in ImageIO.write() to whatever format you
             * actually want
            File file = new File(pathImage3);
            if (file.createNewFile()) {
                ImageIO.write(image3, "bmp", file);
    public class Main {
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            try {
                PictureOverlayTest test = new PictureOverlayTest(
                        "C:\\Users\\Rabee Taha\\Desktop\\Java Test Pics\\test1.png",
                        "C:\\Users\\Rabee Taha\\Desktop\\Java Test Pics\\test2.png",
                        "C:\\Users\\Rabee Taha\\Desktop\\Java Test Pics\\test3.png");
            } catch (IOException e) {
                // TODO Auto-generated catch block
    Here is the link to example images of the outcome ( )

  2. #2
    Join Date
    Jun 1999
    Eastern Florida

    Re: Picture Comparison Code Not Working Properly

    Also posted here:

    Note: Posted code is missing an import statement and will not compile.

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