Re: color space conversions
This seems interesting, thank you. But it converts to grayscale image,
which is a current use case (I think I have found billions code
samples for that). Converting from rgb to cmyk or from cmyk to rgb
really seems to be a hard question (resulting images are too bright or
too dark depending on the direction in my samples).
Any other suggestion ?
Here is a simple program that reads a color image and converts it to
grayscale using ColorConvertOp. Using this as a sample you should be
able to convert anything. I wrote this for a fellow that wanted to draw
a transparent color image over a grayscale image but the ColorConvertOp
is what you are interested in.
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;
public class test6 extends JPanel {
BufferedImage image;
BufferedImage gray;
BufferedImage color;
public test6() {
setPreferredSize(new Dimension(400,300));
try {
// read an image from the disk
image = ImageIO.read(new File("kittens.jpg"));
// create a grayscale image the same size
gray = new BufferedImage(image.getWidth(),image.getHeight(),
BufferedImage.TYPE_BYTE_GRAY);
// create a color image with alpha for output
color = new BufferedImage(400,300,BufferedImage.TYPE_INT_ARGB);
// convert the original colored image to grayscale
ColorConvertOp op = new ColorConvertOp(
image.getColorModel().getColorSpace(),
gray.getColorModel().getColorSpace(),null);
op.filter(image,gray);
// draw the grayscale image on the output image
Graphics g = color.getGraphics();
g.drawImage(gray,0,0,null);
// draw some transparent blue pixels over the whole image
g.setColor(new Color(0,0,255,80));
g.fillRect(0,0,400,300);
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
public void paintComponent(Graphics g) {
g.drawImage(color,0,0,null);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
test6 t6 = new test6();
f.add(t6,BorderLayout.CENTER);
f.pack();
f.setVisible(true);
}
});
}
}
--
Knute Johnson
email s/nospam/knute2008/
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