Re: Sepia tone image filter for Java

Knute Johnson <>
Tue, 15 Jul 2014 10:11:10 -0700
On 7/15/2014 03:59, Roedy Green wrote:

On Mon, 14 Jul 2014 11:24:10 +0200, Joerg Meier <>
wrote, quoted or indirectly quoted someone who said :

Yes, that is typically what happens when you darken blue. On a computer
screen, "darken" means less of a colour ;)

Of course. I was thinking in terms of paint, where adding more blue
paint would be "darkening" the blue.

A sepia tone filter is trickier than I thought. I need to compare the
results from this code with the sepia filter in JavaFX.

import java.awt.*;
import java.awt.color.*;
import java.awt.image.*;
import javax.imageio.*;
import javax.swing.*;

public class test0 extends JPanel {
     private BufferedImage orig,sepia;

     public test0() {
         try {
             URL url = new URL(
             orig =;

             // convert to grayscale and back to RGB
             ColorSpace imgCS = orig.getColorModel().getColorSpace();
             ColorSpace grayCS = ColorSpace.getInstance(ColorSpace.CS_GRAY);
             ColorConvertOp cop = new ColorConvertOp(imgCS,grayCS,null);
             sepia = cop.filter(orig,null);
             cop = new ColorConvertOp(grayCS,imgCS,null);
             sepia = cop.filter(sepia,null);

             // slightly enhance the red, slightly reduce the green and
             // remove half the blue
             float[] factor = new float[] { 1.1f,.9f,.5f };
             float[] offset = new float[] { 0f,0f,0f };
             RescaleOp rop = new RescaleOp(factor,offset,null);
             sepia = rop.filter(sepia,null);
         } catch (Exception e) {

     public void paintComponent(Graphics g2d) {

     public static void main(String... args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame("test0");
                 f.add(new test0(),BorderLayout.CENTER);


Knute Johnson

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