Why Does My Java Image Resize Result in Low Quality, and How Can I Improve It?

Low Image Quality after Resize in Java

The issue arises when resizing an image from a large size (e.g., 300x300) to a significantly smaller size (e.g., 60x60) in a single step. This inevitably leads to quality degradation.

Divide and Conquer Method for Resizing

To mitigate this problem, it is recommended to use a divide and conquer approach.

1. Resize the image to an intermediate size (e.g., 150x150).
2. Resize the intermediate image to the final size (e.g., 60x60).

Example Implementation

Here's a Java code snippet that implements the divide and conquer method:

public class ImageResizer {

    public BufferedImage resize(BufferedImage original, Dimension finalSize) {
        // Get intermediate size.
        Dimension intermediateSize = new Dimension(original.getWidth() / 2, original.getHeight() / 2);

        // Resize to intermediate size.
        BufferedImage intermediateImage = resize(original, intermediateSize);

        // Resize to final size.
        BufferedImage resizedImage = resize(intermediateImage, finalSize);
        
        // Return the resized image.
        return resizedImage;
    }

    private BufferedImage resize(BufferedImage image, Dimension size) {
        BufferedImage scaledImage = new BufferedImage(size.width, size.height, image.getType());
        Graphics2D graphics = scaledImage.createGraphics();

        // Set rendering hints for better quality.
        graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        graphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // Draw the original image scaled to the new size.
        graphics.drawImage(image, 0, 0, size.width, size.height, null);
        
        // Dispose of the graphics object.
        graphics.dispose();

        // Return the scaled image.
        return scaledImage;
    }
}

By using this method, you can achieve significantly improved image quality after resizing.

The above is the detailed content of Why Does My Java Image Resize Result in Low Quality, and How Can I Improve It?. For more information, please follow other related articles on the PHP Chinese website!