Re: ImageIO.write - compression

From:
"Rupert Woodman" <NoEmail@com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 8 Apr 2007 16:52:31 +0100
Message-ID:
<46190fdc$0$8729$ed2619ec@ptn-nntp-reader02.plus.net>
Just to ellucidate a little. I originally had code such as this shown
below. Whatever I pass into the setCompressionQuality() method (i.e. any of
0.05, 0.75, 0.95), results in a written file of 811kb, so I assumed this
code was bad. I don't see why tho.

The BufferedImage passed to this method is created with:

BufferedImage bi = ImageIO.read(new File(c.getInputFileName()));

public void myWrite(BufferedImage bi)
{
  Iterator writers = ImageIO.getImageWritersByFormatName("jpg");
  ImageWriter writer = (ImageWriter)writers.next();
  ImageWriteParam param = writer.getDefaultWriteParam();
  param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
  System.err.println("getCompressionType: " + param.getCompressionType());

  System.err.println("1 getCompressionQuality: " +
param.getCompressionQuality());
  param.setCompressionQuality(0.05f);
  System.err.println("2 getCompressionQuality: " +
param.getCompressionQuality());

  try {
    File ff = new File("c:/development/temp/xxx.jpg");
    ImageOutputStream ios = ImageIO.createImageOutputStream(ff);
    writer.setOutput(ios);
    writer.write(bi);
  } catch (IOException e) {
    e.printStackTrace();
  }
}

Many thanks

"Rupert Woodman" <NoEmail@com> wrote in message
news:46190521$0$8736$ed2619ec@ptn-nntp-reader02.plus.net...

Hi,

I have the following code:

String inputFilename = "input.jpg";
String outputFilename = "output.jpg";

BufferedImage bi = ImageIO.read(new File(inputFilename()));
ImageIO.write(bi, "jpg", new File(outputFilename));

The original file is about 1.5 meg in size, the written file is 240kb.
What I don't understand is what changes have been made to the image (I've
not specified any), and how I can control those changes?

Thank you for any thoughts you may have.

rgds

Rupert

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