Adjust JPEG image compression quality when saving images in Java

If you’ve been using the imageIO.write method to save JPEG images, you may notice that some image lose quality. This is because you can’t instruct the imagIO.write method to apply a certain compression quality to the images.

Using the imageIO.write method to save JPEG images is simple, but doesn’t give you the control you need to adjust compression quality:

ImageIO.write(bufferedimage, "jpeg", file);

If you’re willing to write a few extra lines of code, the Java Imaging API offers another way.

The following imports will be necessary:

import java.io.File;
import java.util.Iterator;
import javax.imageio.*;
import javax.imageio.stream.*;

You first need to enumerate the image writers that are available to your configuration:

Iterator iter = ImageIO.getImageWritersByFormatName("jpeg");

Then, choose the first image writer available (unless you want to choose a specific writer) and create an ImageWriter instance:

ImageWriter writer = (ImageWriter)iter.next();
// instantiate an ImageWriteParam object with default compression options
ImageWriteParam iwp = writer.getDefaultWriteParam();

Now, we can set the compression quality:

iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(1);   // an integer between 0 and 1
// 1 specifies minimum compression and maximum quality


Output the file:

File file = new File(OUTPUTFILE);
FileImageOutputStream output = new FileImageOutputStream(file);
writer.setOutput(output);
IIOImage image = new IIOImage(BUFFEREDIMAGE, null, null);
writer.write(null, image, iwp);
writer.dispose();