This is an approach to scaling an image in Java without the distortion that come from changing the aspect ratio. The source code is HERE

 



import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;


public class ImageScaler {
/**
* Scale an image while preserving aspect ratio
*
* @param args Name of image file to be scaled (testing only)
*
*/
public static void main(String[] args) throws Exception {
BufferedImage in = javax.imageio.ImageIO.read(new java.io.File(args[0]));
BufferedImage out = ImageScaler.scaleImage(in,
BufferedImage.TYPE_INT_RGB, 100, 200);
javax.imageio.ImageIO.write(out, "JPG", new java.io.File("scaled.jpg"));
}

/**
*
* @param image The image to be scaled
* @param imageType Target image type, e.g. TYPE_INT_RGB
* @param newWidth The required width
* @param newHeight The required width
*
* @return The scaled image
*/
public static BufferedImage scaleImage(BufferedImage image, int imageType,
int newWidth, int newHeight) {
// Make sure the aspect ratio is maintained, so the image is not distorted
double thumbRatio = (double) newWidth / (double) newHeight;
int imageWidth = image.getWidth(null);
int imageHeight = image.getHeight(null);
double aspectRatio = (double) imageWidth / (double) imageHeight;

if (thumbRatio < aspectRatio) {
newHeight = (int) (newWidth / aspectRatio);
} else {
newWidth = (int) (newHeight * aspectRatio);
}

// Draw the scaled image
BufferedImage newImage = new BufferedImage(newWidth, newHeight,
imageType);
Graphics2D graphics2D = newImage.createGraphics();
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.drawImage(image, 0, 0, newWidth, newHeight, null);

return newImage;
}
}