CMYK to RGB conversion with icc profile. Output is too dark

Question

Similar question has been asked many times. But I didn't found the answer.
It looks like this code cmykToRgb.filter(r, resultRaster) doesn't convert anything.
But I presume each pixel from the raster "r" should be converted to RGB colorSpace and put into the resultRaster. Am I right?
Any help appreciated.
That profile file got from adobe site.
see
[before image|http://i.stack.imgur.com/HHGes.png]
[after image|http://i.stack.imgur.com/4erZj.png]
Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName("jpeg");
ImageReader reader = null;
while (readers.hasNext()){
      reader = readers.next();
      if (reader.canReadRaster()){
          break;
// read
ImageInputStream ios = ImageIO.createImageInputStream(new FileInputStream(new File(myPic.jpg)));
reader.setInput(ios);
Raster r = reader.readRaster(0, null);
BufferedImage result = new BufferedImage(r.getWidth(), r.getHeight(), bufferedImage.TYPE_INT_RGB);
WritableRaster resultRaster = result.getRaster();
ICC_Profile iccProfile = ICC_Profile.getInstance(new File("profile_name.icc");
ColorSpace cs = new ICC_ColorSpace(iccProfile);
ColorConvertOp cmykToRgb = new ColorConvertOp(cs, result.getColorModel().getColorSpace(), null);
cmykToRgb.filter(r, resultRaster);
// write
ImageIo.write(resul, "jpg", new File("myPic.jpg"));Thanks
Edited by: n0d on Nov 15, 2011 4:59 AM

Answer 1

From the javax_imageio_jpeg_image_1.0 specification:
If an Adobe APP14 marker segment is present, the colorspace is determined by consulting the transform flag. The transform flag takes one of three values:
2 - The image is encoded as YCCK (implicitly converted from CMYK on encoding).
1 - The image is encoded as YCbCr (implicitly converted from RGB on encoding).
0 - Unknown. 3-channel images are assumed to be RGB, 4-channel images are assumed to be CMYK.What it's talking about is the metadata returned from ImageReader#getImageMetadata. For jpeg's, it has the following structure.
javax_imageio_jpeg_imageio_1.0
     JPEGVariety
          app0JFIF
               app2ICC (if present, user object is ICC_Profile)
     markerSequence
          app14Adobe
               transform Value (0, 1, or 2)Basically if the transform value is 2 then it's YCCK->CMYK->RGB. If the transform value is 1, then it's YCC->RGB. If the transform value is 0, then it's CMYK->RGB if the raster has 4 bands, otherwise it's already in RGB if it has 3 bands.
The problem is that the default JPEGImageReader that comes with installing java is buggy. It usually throws an exception if you try to read the metadata of a cmyk jpeg. So the bad news is that you're sort of out of luck on that front.
The good news is that Sun did create a jpeg reader that can read any jpeg, including a cmyk one. It's called the CLibJPEGImageReader and you get it with installing JAI-ImageIO - http://download.java.net/media/jai-imageio/builds/release/1.1/ . It's a 'natively' accelerated ImageReader that doesn't have all the bells and whisles of your standard ImageReader. It can't read rasters, the writer can't write custom metadata, but it's fast and can read essentially all jpegs.