Converting BufferedImage to Mat (OpenCV) in Java [duplicate]

Answer 1

You can try this method, to actually convert the image to TYPE_3BYTE_BGR (your code simply created a blank image of the same size, that is why it was all black).

Usage:

// Convert any type of image to 3BYTE_BGR
im = toBufferedImageOfType(im, BufferedImage.TYPE_3BYTE_BGR);

// Access pixels as in original code

And the conversion method:

public static BufferedImage toBufferedImageOfType(BufferedImage original, int type) {
    if (original == null) {
        throw new IllegalArgumentException("original == null");
    }

    // Don't convert if it already has correct type
    if (original.getType() == type) {
        return original;
    }

    // Create a buffered image
    BufferedImage image = new BufferedImage(original.getWidth(), original.getHeight(), type);

    // Draw the image onto the new buffer
    Graphics2D g = image.createGraphics();
    try {
        g.setComposite(AlphaComposite.Src);
        g.drawImage(original, 0, 0, null);
    }
    finally {
        g.dispose();
    }

    return image;
}