I am trying to bring the functionality of the Matlab's imrotate function to Java. In details, as I have stored an image's pixel values in a 2d array, I want to rotate this image around its center with a specified angle. Most of the answers I have found (using AffineTransform and Graphics2D with BufferedImage) were graphics-oriented and I was not able to produce the result I need as I do not need to draw it visually. For example, the following function returned an image whose all pixel values were 0 (I commented out the visualization part)

public static BufferedImage rotateImage(BufferedImage img, double angle) {
        double rads = Math.toRadians(angle);
        double sin = Math.abs(Math.sin(rads)), cos = Math.abs(Math.cos(rads));
        int w = img.getWidth();
        int h = img.getHeight();
        int newWidth = (int) Math.floor(w * cos   h * sin);
        int newHeight = (int) Math.floor(h * cos   w * sin);

        BufferedImage rotated = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = rotated.createGraphics();
        AffineTransform at = new AffineTransform();
        at.translate((newWidth - w) / 2, (newHeight - h) / 2);

        int x = w / 2;
        int y = h / 2;

        at.rotate(rads, x, y);
        g2d.setTransform(at);
//        g2d.drawImage(img, 0, 0, this);
//        g2d.setColor(Color.RED);
//        g2d.drawRect(0, 0, newWidth - 1, newHeight - 1);
//        g2d.dispose();

        return rotated;

Any help or suggestion is much appreciated. Also, please tell me if you need further details.

UPDATE: I think I should clarify my question better. So I have a fingerprint image and I need to extract a sub-image from it. After that, I have to rotate the sub-image based on an angle provided. What I have tried was: First, load the image in as a BufferedImage. Then, I extracted the sub-image as a 2-dimensional array of integers. Finally, I need to apply the rotation. As I did some research, I know it sounds silly and I probably am but I tried to create a BufferedImage with the sub-image's 2d array, then rotate with the method given down there. Yet, I was not successful. I look forward to hearing your comments on what I did wrong conceptually or programmatically. Thank you very much.

CodePudding user response：

As pointed out in comments, the following answer might be useful for this question:

I have a code that shears the image but i would like it to rotate on the x and y axis with forward and backward mapping. Any advice on how to do this?