High-Quality Image Resize with Java

Okay, but why not use a real high quality (and fast) algorithm?
http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html

@Stefan Krause
Hi Stefan, thanks for commenting.
This approach is good because it is simple.
I don't use any fancy algorithm that could impact on performance (like the one you suggested, which seems to be the right direction).
For web servers that handle millions of requests every day, a simple approach like this might fit well.
I am aware that this isn't a perfect solution, but the performance is good and the final image is nice for most cases.
So why not consider it?
Regards,
Hugo Teixeira

nice trick!

This is an interesting approach but unfortunately flawed. First of all you setup a bunch of useless rendering hints (like antialiasing). But the real problem is that a blur requires more operations than a bilinear resize. An easy and fast way to produce good looking thumbnails is to scale the image by half its size, using BILINEAR, until you reach the final size you want.

I won't go further into details but I highly recommend you to read Chris Campbell's article on the matter (that Stefan already posted): http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html

The algorithm proposed in Chris' article is *not* fancy at all. And it's pretty fast. Chet and I timed the various approaches and discussed them at length in our book Filthy Rich Client and in a couple of JavaOne presentations and the progressive bilinear approach is very very fast.

@Romain Guy
Hi Romain, thanks for your nice feedback.
I agree with your comments and your expertise is very important at this moment.
I just want to clarify some points that might have been misunderstood:

1 - The rendering hints in the resize() method aren't that useless. They do produce better results (compared to the same method without them), although not as good as a high-quality resize (the hints in the blur() method might be useless though).

2 - You are right in the sense that a blur requires more operations than a bilinear resize, but I don't run the blur in the original image. First I reduce the size to height/width = 100 and then I run the blur. This is a completely different situation and creates a whole new scenario for performance analysis. So the question is: Is a blur in a small image faster than having a bilinear resize run several times? The fact is, we don't know the answer and it depends on the situation. So "flawed" might be a strong word in this sense.

Anyway, I am not fully concerned about the fate of this approach since we have a correct way of doing things. But I have to admit that it was nice to develop it and funny at the same time due to the unusual implementation.

Best regards,
Hugo Teixeira

Thanks a lot, your code works very well.

the best time i've got is 31ms for an 5k image, it
is pretty good for a dev machine
(pentuim IV 2.4Ghz 1.5G ram Tomcat Eclipse Postgres launched)

Regards
FM

Very nice. I will stop my search here and thank you.......

Thanks for your approach. The resize works fine for me with a .jpg, but not createCompatibleImage(...). When i write the picture, i have a black picture, with the right dimension. i don't understand why. Have you got an idea ?

Hugo,

Thanks a ton for this article. I've been wrestling with image quality for resizing JPEG's in Java for a bit now, and your trick helped a ton.

I documented my results here:

http://www.byfolio.com/roller/blog/entry/hugo_saves_the_day_for

Thanks!

Cory

Try this ;)

http://www.comesolvego.com/2008/04/29/resize-images-with-java-high-quality-and-working-solution/

guys... have been strugling a lot. need to resize the image since the source of image is remote place. i dont know the size of incoming image and sadly i have limited space on my swing app to display it... best solution to resize it is ?? heeeeeeeeeeelp

hey, this is simple and the best. i have been trying to search this for a long time. Finaly I got it. Thanx a lot.

This solution worked pretty well for me.
thx a lot

I test the giving code but it give a bad quality, i founded an other java code can give you a more better quality




package com.diwansoft.resizer;

import com.sun.image.codec.jpeg.JPEGImageEncoder;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import javax.swing.*;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.image.Kernel;
import java.awt.image.ConvolveOp;

public class ImageUtil {

public static void resize(File originalFile, File resizedFile, int newWidth, float quality) throws IOException {

if (quality 1) {
throw new IllegalArgumentException("Quality has to be between 0 and 1");
}

ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());
Image i = ii.getImage();
Image resizedImage = null;

int iWidth = i.getWidth(null);
int iHeight = i.getHeight(null);

if (iWidth > iHeight) {
resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);
} else {
resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight, newWidth, Image.SCALE_SMOOTH);
}

// This code ensures that all the pixels in the image are loaded.
Image temp = new ImageIcon(resizedImage).getImage();

// Create the buffered image.
BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null), temp.getHeight(null),
BufferedImage.TYPE_INT_RGB);

// Copy image to buffered image.
Graphics g = bufferedImage.createGraphics();

// Clear background and paint the image.
g.setColor(Color.white);
g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));
g.drawImage(temp, 0, 0, null);
g.dispose();

// Soften.
float softenFactor = 0.05f;
float[] softenArray = {0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0};
Kernel kernel = new Kernel(3, 3, softenArray);
ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
bufferedImage = cOp.filter(bufferedImage, null);

// Write the jpeg to a file.
FileOutputStream out = new FileOutputStream(resizedFile);

// Encodes image as a JPEG data stream
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bufferedImage);

param.setQuality(quality, true);

encoder.setJPEGEncodeParam(param);
encoder.encode(bufferedImage);
}

// Example usage
public static void main(String[] args) throws IOException {
File originalImage = new File("C:\Documents and Settings\Kamal Haddad\workspace\Flex\WebContent\projects\test\snapshots\fullsize\1.jpeg");
resize(originalImage, new File("C:\Documents and Settings\Kamal Haddad\workspace\Flex\WebContent\projects\test\snapshots\fullsize\1-7.jpeg"), 400, 0.7f);
resize(originalImage, new File("C:\Documents and Settings\Kamal Haddad\workspace\Flex\WebContent\projects\test\snapshots\fullsize\1-1.jpeg"), 400, 1f);
}

}

Hi
Can you not simply use the 'getScaledInstance' method of the Image (extended to BufferedImage) class. You can select different quality levels.. e.g. Image.SCALE_SMOOTH. I don't think it's the fastest but I read somewhere it is high quality output? I'd be interested in what you think about this method.

I have another suggestion for you, use SVG. You can use the batik libraries, or svgSalamander - a very lightweight SVG rendering Java component. What's even cooler is you can also animate the image with the SVG animation tools.

@Michael
Hi Michael,
The Image.getScaledInstance is VERY slow.. I was using that initially and was disappointed. The quality is good, but because it's done all in software it is very slow.

I finally decided upon:
org.jdesktop.swingx.graphics.GraphicUtilities
and the GraphicUtilities.createThumbnail() method.
It is part of the SwingX download from http://swinglabs.org/

It uses multiple intermediate bi-linear resizes from a managed bufferedimage's drawImage to resize in steps to preserve image quality.


See the following bug report with good comments about the getScaledImage() method http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6196792

I have developed a library called ThumbMaster which is specifically targeted at Java programmers who need to resize images with JAI -- and get high quality results. It is implemented as a new JAI interpolation, and so the standard built-in operators (and their native acceleration) can all be used. Image quality and file size are both nearly identical to the results of ImageMagick, as they are both based heavily on the same image processing algorithms.

For more information and a trial download, visit http://www.devella.net/thumbmaster

this solution is very helpful
thank you

Very helpful. Thank you.