Re: [JAI-ImageIO] color space conversions

Knute Johnson <>
Thu, 12 Jun 2008 08:06:46 -0700
patriarch24 wrote:

 Hello all,
I'm new to image processing (not to Java), and I try hard to do a
thing that seems simple to me : convert images' color space to another
color space.
As input, I can get many formats (mainly jpeg, then png and tiff) in
different color spaces (mainly RGB, then CMYK) and I want to transform
all inputs in tiff/sRGB.
Converting the encoding in tiff is pretty simple using JAI (operator
encode does the stuff), but I can't figure out the use of the
"ColorConvert" operator (that seems simple, but by the way it's not).
I tried many code samples from all the web, mixing JAI and the
standard API, but never got a good result.

Thanks in advance.
The two main problems are :
- the ColorModel and image SampleModel are not compatible
- the convertion is done but the resulting image is negative.

So my question is : how can I convert from a color space to another
the simplest (and the right) way ?


I managed to write a code creating an output, but this output is
really darker than the initial one. This is the code (got it from the
web) :


private static void convertToCmykColorSpace(String fileName) {
PlanarImage planarImage = JAI.create("fileload", fileName);
ColorModel colorModelInput = planarImage.getColorModel();
ColorSpace colorSpaceInput = colorModelInput.getColorSpace();
ICC_Profile profileOutput = null;
try {
profileOutput = ICC_Profile.getInstance("C:/java/libs/JAI/");
} catch (IOException e) {
ColorSpace colorspaceOutput = new ICC_ColorSpace(profileOutput);
PlanarImage planarImageProfile = convertColorSpace(planarImage,
colorSpaceInput, colorspaceOutput);

File imageFile = new File(fileName);
String newFilename = FilenameUtils.getFullPath(fileName)
+ FilenameUtils.getBaseName(fileName) + "_convertedtocmyk."
+ FilenameUtils.getExtension(fileName);

JAI.create("filestore", planarImageProfile, newFilename);

private static PlanarImage convertColorSpace(PlanarImage
ColorSpace colorSpaceInput, ColorSpace colorSpaceOutput) {

ColorModel colorModelInput = RasterFactory.createComponentColorModel(
colorSpaceInput, false, false, Transparency.OPAQUE);

ImageLayout imageLayoutInput = new ImageLayout();
RenderingHints RenderingHintsInput = new RenderingHints(
JAI.KEY_IMAGE_LAYOUT, imageLayoutInput);
ParameterBlock parameterBlockInput = new ParameterBlock();
PlanarImage planarInputImageInputWithProfile = JAI.create("format",
parameterBlockInput, RenderingHintsInput);

ColorModel colorModelOutput = RasterFactory
.getSampleModel().getDataType(), colorSpaceOutput,
false, false, Transparency.OPAQUE);

ImageLayout imageLayoutOutput = new ImageLayout();
.getWidth(), planarInputImageInputWithProfile
RenderingHints renderingHintsOutput = new RenderingHints(
JAI.KEY_IMAGE_LAYOUT, imageLayoutOutput);
ParameterBlock parameterBlockOutput = new ParameterBlock();

return JAI.create("ColorConvert", parameterBlockOutput,


Can anyone help me ?

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 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 = File("kittens.jpg"));

             // create a grayscale image the same size
             gray = new BufferedImage(image.getWidth(),image.getHeight(),

             // 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(

             // draw the grayscale image on the output image
             Graphics g = color.getGraphics();

             // draw some transparent blue pixels over the whole image
             g.setColor(new Color(0,0,255,80));
         } catch (IOException ioe) {

     public void paintComponent(Graphics g) {

     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame();

                 test6 t6 = new test6();


Knute Johnson
email s/nospam/knute2008/

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