Flipping a BufferedImage horizontally

Question

I'm using the following code to flip an image horizontally. It works, but the image is flipped horizontally and also vertically at the same time. Right facing image, now faces left, but is also vertically flipped. How can I stop the vertical flip? Code:

public static BufferedImage createRotated( BufferedImage image)
    {
        AffineTransform at = AffineTransform.getRotateInstance(
            Math.PI, image.getWidth()/2, image.getHeight()/2 );
        return createTransformed(image, at);
    }

public static BufferedImage createTransformed(   BufferedImage image, AffineTransform at)
    {
        BufferedImage newImage = new BufferedImage(
            image.getWidth(), image.getHeight(),
            BufferedImage.TYPE_INT_ARGB);
        Graphics2D gg = newImage.createGraphics();
        gg.transform(at);
        gg.drawImage(image, 0, 0, null);
        gg.dispose();
        return newImage;
    }

The code is from this answer: http://stackoverflow.com/questions/23457754/how-to-flip-bufferedimage-in-java — Sumit Kumar, Jun 08 '16 at 15:04

score 2 · Accepted Answer · edited May 23 '17 at 12:31

2

Because you are rotating the image of 180 degrees, not flipping it.

Use the AffineTransform.getScaleInstance(-1, 1); instead.

EDIT: From here: https://stackoverflow.com/a/9559043/1542532

// Flip the image horizontally
tx = AffineTransform.getScaleInstance(-1, 1);
tx.translate(-image.getWidth(null), 0);

You must also translate the image because the scale will move the image to the left.

edited May 23 '17 at 12:31

Community

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answered Jun 08 '16 at 15:13

Mauro Valvano

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Hi, Many thanks! This also explained a lot of other things about flipping images. – Sumit Kumar Jun 08 '16 at 15:32

Pino · Answer 2 · 2016-06-08T15:44:33.503

I've made some performance test and this is a bit more efficient than using AffineTransform:

public static BufferedImage flipHoriz(BufferedImage image) {
    BufferedImage newImage = new BufferedImage(image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);
    Graphics2D gg = newImage.createGraphics();
    gg.drawImage(image, image.getHeight(), 0, -image.getWidth(), image.getHeight(), null);
    gg.dispose();
    return newImage;
}

Flipping a BufferedImage horizontally

2 Answers2