Introduction
This will guide you through how to rescale images using this library.
A simple rescale
Lets say that you have a BufferedImage instance called tomato that should be rescaled to 100x200. If you want a high quality rescale, you should choose the ResampleOp class:
ResampleOp resampleOp = new ResampleOp (100,200);
BufferedImage rescaledTomato = resampleOp.filter(tomato, null);
Tip: You might need to increase your maximum heap. This can be done using the -Xmx parameter, such as: java -Xmx512m MyJavaClass
Using Unsharpen Filter
Let's improve the quality a bit more adding a unsharpen filter to the final image. This will remove some of blur, that a rescale operation creates.
ResampleOp resampleOp = new ResampleOp (100,200);
resampleOp.setUnsharpenMask(AdvancedResizeOp.UnsharpenMask.Normal);
BufferedImage rescaledTomato = resampleOp.filter(tomato, null);
Adding a listener
If your tomato image was very large, this might take some time. The following code add a change listener so the user can see that the computer is actually is working.
ResampleOp resampleOp = new ResampleOp (100,200);
resampleOp.setUnsharpenMask(AdvancedResizeOp.UnsharpenMask.Normal);
resampleOp.addProgressListener(new ProgressListener() {
public void notifyProgress(float fraction) {
System.out.printf("Still working - %f percent %n",fraction*100);
}
});
BufferedImage rescaledTomato = resampleOp.filter(tomato, null);
Could you please add some more examples. I was particularly interested in using this library for down-sizing images uploaded to my spring mvc web application. Could you perhaps provide a full example for that?
The library looks very interesting though, and the third party Filters are also awesome.
works very well with this sample code:
public class Test { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { File f = new File("C:\\image resizer\\0776171_L.jpg"); BufferedImage src = ImageIO.read(f); ResampleOp resampleOp = new ResampleOp (76,76); resampleOp.setUnsharpenMask(AdvancedResizeOp.UnsharpenMask.VerySharp); BufferedImage rescaled = resampleOp.filter(src, null); ImageIO.write(rescaled, "JPG", new File("C:\\image resizer\\0776171_L76.jpg")); } }If it not works, you can do like this
BufferedImage? rescaled = resampleOp.doFilter(src, null, 76, 76);