Java image resize, maintain aspect ratio

Question

I have an image which I resize:

if((width != null) || (height != null)) {     try{         // scale image on disk         BufferedImage originalImage = ImageIO.read(file);         int type = originalImage.getType() == 0? BufferedImage.TYPE_INT_ARGB                                                : originalImage.getType();          BufferedImage resizeImageJpg = resizeImage(originalImage, type, 200, 200);         ImageIO.write(resizeImageJpg, "jpg", file);          } catch(IOException e) {            System.out.println(e.getMessage());        } } 

This is how I resize the image:

private static BufferedImage resizeImage(BufferedImage originalImage, int type,                                          Integer img_width, Integer img_height) {     BufferedImage resizedImage = new BufferedImage(img_width, img_height, type);     Graphics2D g = resizedImage.createGraphics();     g.drawImage(originalImage, 0, 0, img_width, img_height, null);     g.dispose();      return resizedImage; } 

Now the problem is, I also need to maintain aspect ratio. That is, I need the new 200/200 image to contain the new image scaled. Something like this:

I tried some things but they didn't work out as expected. Any help is appreciated. Thanks alot.

Answer 1

Here we go:

Dimension imgSize = new Dimension(500, 100); Dimension boundary = new Dimension(200, 200); 

Function to return the new size depending on the boundary:

public static Dimension getScaledDimension(Dimension imgSize, Dimension boundary) {      int original_width = imgSize.width;     int original_height = imgSize.height;     int bound_width = boundary.width;     int bound_height = boundary.height;     int new_width = original_width;     int new_height = original_height;      // first check if we need to scale width     if (original_width > bound_width) {         //scale width to fit         new_width = bound_width;         //scale height to maintain aspect ratio         new_height = (new_width * original_height) / original_width;     }      // then check if we need to scale even with the new height     if (new_height > bound_height) {         //scale height to fit instead         new_height = bound_height;         //scale width to maintain aspect ratio         new_width = (new_height * original_width) / original_height;     }      return new Dimension(new_width, new_height); } 

In case anyone also needs the image resizing code, here is a decent solution.

If you're unsure about the above solution, there are different ways to achieve the same result.

Answer 2

Translated from here:

Dimension getScaledDimension(Dimension imageSize, Dimension boundary) {      double widthRatio = boundary.getWidth() / imageSize.getWidth();     double heightRatio = boundary.getHeight() / imageSize.getHeight();     double ratio = Math.min(widthRatio, heightRatio);      return new Dimension((int) (imageSize.width  * ratio),                          (int) (imageSize.height * ratio)); } 

You can also use imgscalr to resize images while maintaining aspect ratio:

BufferedImage resizeMe = ImageIO.read(new File("orig.jpg")); Dimension newMaxSize = new Dimension(255, 255); BufferedImage resizedImg = Scalr.resize(resizeMe, Method.QUALITY,                                         newMaxSize.width, newMaxSize.height);