Re-sizing an image without losing quality

The best article I have ever read on this topic is The Perils of Image.getScaledInstance() (web archive).

In short: You need to use several resizing steps in order to get a good image. Helper method from the article:

public BufferedImage getScaledInstance(BufferedImage img,
                                       int targetWidth,
                                       int targetHeight,
                                       Object hint,
                                       boolean higherQuality)
{
    int type = (img.getTransparency() == Transparency.OPAQUE) ?
        BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
    BufferedImage ret = (BufferedImage)img;
    int w, h;
    if (higherQuality) {
        // Use multi-step technique: start with original size, then
        // scale down in multiple passes with drawImage()
        // until the target size is reached
        w = img.getWidth();
        h = img.getHeight();
    } else {
        // Use one-step technique: scale directly from original
        // size to target size with a single drawImage() call
        w = targetWidth;
        h = targetHeight;
    }

    do {
        if (higherQuality && w > targetWidth) {
            w /= 2;
            if (w < targetWidth) {
                w = targetWidth;
            }
        }

        if (higherQuality && h > targetHeight) {
            h /= 2;
            if (h < targetHeight) {
                h = targetHeight;
            }
        }

        BufferedImage tmp = new BufferedImage(w, h, type);
        Graphics2D g2 = tmp.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
        g2.drawImage(ret, 0, 0, w, h, null);
        g2.dispose();

        ret = tmp;
    } while (w != targetWidth || h != targetHeight);

    return ret;
}