How to convert from CMYK to RGB in Java correctly?

My Java code to convert a CMYK jpeg to RGB results in the output image being far too light - see code below. Can anyone suggest the correct way to do the conversion?

The following code requires Java Advanced Image IO to read the jpeg and example-cmyk.jpg

import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.io.File;

import javax.imageio.ImageIO;

public class TestCmykToRgb {

    public static void main(String[] args) throws Exception {
        BufferedImage cmykImage = ImageIO.read(new File(
                "j:\\temp\\example-cmyk.jpg"));


        BufferedImage rgbImage = new BufferedImage(cmykImage.getWidth(),
                cmykImage.getHeight(), BufferedImage.TYPE_INT_RGB);

        ColorConvertOp op = new ColorConvertOp(null);
        op.filter(cmykImage, rgbImage);

        ImageIO.write(rgbImage, "JPEG", new File("j:\\temp\\example-rgb.jpg"));

    }
}

java cmyk

Edit Report

There is a lot of good stuff in the existing answers already. But none of them is a complete solution that handles the different kinds of CMYK JPEG images.

For CMYK JPEG images, you need to distinguish between regular CMYK, Adobe CMYK (with inverted values, i.e. 255 for no ink and 0 for maximum ink) and Adobe CYYK (some variant with inverted colors as well).

This solution here requires Sanselan (or Apache Commons Imaging as it's called now) and it requires a reasonable CMYK color profile (.icc file). You can get the later one from Adobe or from eci.org.

public class JpegReader {

    public static final int COLOR_TYPE_RGB = 1;
    public static final int COLOR_TYPE_CMYK = 2;
    public static final int COLOR_TYPE_YCCK = 3;

    private int colorType = COLOR_TYPE_RGB;
    private boolean hasAdobeMarker = false;

    public BufferedImage readImage(File file) throws IOException, ImageReadException {
        colorType = COLOR_TYPE_RGB;
        hasAdobeMarker = false;

        ImageInputStream stream = ImageIO.createImageInputStream(file);
        Iterator<ImageReader> iter = ImageIO.getImageReaders(stream);
        while (iter.hasNext()) {
            ImageReader reader = iter.next();
            reader.setInput(stream);

            BufferedImage image;
            ICC_Profile profile = null;
            try {
                image = reader.read(0);
            } catch (IIOException e) {
                colorType = COLOR_TYPE_CMYK;
                checkAdobeMarker(file);
                profile = Sanselan.getICCProfile(file);
                WritableRaster raster = (WritableRaster) reader.readRaster(0, null);
                if (colorType == COLOR_TYPE_YCCK)
                    convertYcckToCmyk(raster);
                if (hasAdobeMarker)
                    convertInvertedColors(raster);
                image = convertCmykToRgb(raster, profile);
            }

            return image;
        }

        return null;
    }


                        
                        
                            answered 2012-08-26T18:09:48.607

How to convert from CMYK to RGB in Java correctly?

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