Image resizing and cropping

Original image:

)

End file : 200x200

Crop with .getSubimage()

It's work fine, because he is not lose quality. But you can get incorrect image

For, example:

Source code:

    BufferedImage originalImage = ImageIO.read(new File("img/original.jpg"));
    BufferedImage subImage = originalImage.getSubimage(300, 150, 200, 200);
    File outputFile = new File("img/croppedImage.jpg");
    ImageIO.write(subImage, "jpg", outputFile);

So, we need image resizing

There is two ways to do it:

• Raw Java SE methods
• Use external libraries with Progressive Scaling

Using Graphics 2D

    public static void main(String[] args)  {
        try {
            BufferedImage originalImage = ImageIO.read(new File("img/original.jpg"));

            BufferedImage resizedImage = createResizedCopy(originalImage, 200, 200, true);

            File outputFile = new File("img/resizedImage.jpg");
            ImageIO.write(resizedImage, "jpg", outputFile);

        } catch (IOException e){
            e.printStackTrace();
        }
    }

    static BufferedImage createResizedCopy(Image originalImage, int scaledWidth, int scaledHeight, boolean preserveAlpha)
    {
        int imageType = preserveAlpha ? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
        BufferedImage scaledBI = new BufferedImage(scaledWidth, scaledHeight, imageType);
        Graphics2D g = scaledBI.createGraphics();
        if (preserveAlpha) {
            g.setComposite(AlphaComposite.Src);
        }
        g.drawImage(originalImage, 0, 0, scaledWidth, scaledHeight, null);
        g.dispose();
        return scaledBI;
    }

Result:

Yeah, we have the worst quality.

Using libraries with Progressive Scaling

So, I used fastest library (in my opinion) for this task

Thumbnailator

Uses the progressive bilinear algorithm if the target is at least half of every dimension, otherwise it uses simple Graphics2d bilinear scaling and bicubic for upscaling.

Source code:

    BufferedImage imageToScale = ImageIO.read(new File("img/original.jpg"));
    int dWidth = 200;
    int dHeight = 200;
    Resizer resizer = DefaultResizerFactory.getInstance().getResizer(
            new Dimension(imageToScale.getWidth(), imageToScale.getHeight()),
            new Dimension(dWidth, dHeight));

    BufferedImage scaledImage = new FixedSizeThumbnailMaker(
            dWidth, dHeight, false, true).imageType(BufferedImage.TYPE_INT_RGB).resizer(resizer).make(imageToScale);

    ImageIO.write(scaledImage, "jpg", new File("img/thumbnailatorImage.jpg"));
    System.out.println("Successful!");

Result:

Resizing and cropping

Now, lets combine this methods to get really good scaled avatars for users:

    // we use here all!

    final int WIDTH = 200;
    final int HEIGHT = 200;
    BufferedImage originalImage = ImageIO.read(new File("img/original.jpg"));

    // let's crop first, because we need to save image properties before scaling

    // So, we need to make x == y
    BufferedImage subImage;
    int delta = originalImage.getHeight() - originalImage.getWidth();

    if (delta > 0) {
        subImage = originalImage.getSubimage(0, delta/2 , originalImage.getWidth(), originalImage.getHeight() - delta);
    } else if (delta < 0){
        subImage = originalImage.getSubimage(-delta/2, 0 , originalImage.getWidth() + delta, originalImage.getHeight());
    } else {
        subImage = originalImage;
    }

    // Now we can resize our image to our dimensions

    Resizer resizer = DefaultResizerFactory.getInstance().getResizer(
            new Dimension(subImage.getWidth(), subImage.getHeight()),
            new Dimension(WIDTH, HEIGHT));

    BufferedImage scaledImage =
            new FixedSizeThumbnailMaker(WIDTH, HEIGHT, false, true)
                    .imageType(BufferedImage.TYPE_INT_RGB)
                    .resizer(resizer)
                    .make(subImage);

    ImageIO.write(scaledImage, "jpg", new File("img/resizedAndCropped.jpg"));

Result: