Java实现把cmyk格式图片转换为RGB格式图片

package com.pb.util;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
import java.awt.Transparency;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.ComponentColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferByte;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import javax.imageio.IIOException;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
/**
 * 把cmyk格式图片转换为RGB格式
 * @author Administrator
 *
 */
public class CMYK {
      public void readImage(String filename) throws IOException {        
           File file = new File(filename);
            ImageInputStream input = ImageIO.createImageInputStream(file);
            Iterator readers = ImageIO.getImageReaders(input);
            if(readers == null || !readers.hasNext()) {
                throw new RuntimeException("1 No ImageReaders found");
            }
            ImageReader reader = (ImageReader) readers.next();
            reader.setInput(input);
            String format = reader.getFormatName() ;
            BufferedImage image; 
           
          if ( "JPEG".equalsIgnoreCase(format) ||"JPG".equalsIgnoreCase(format) )   {            
            try {  
                // 尝试读取图片 (包括颜色的转换).   
                image = reader.read(0); //RGB
            } catch (IIOException e) {  
                // 读取Raster (没有颜色的转换).   
                Raster raster = reader.readRaster(0, null);//CMYK  
                image = createJPEG4(raster);
            } 
               image.getGraphics().drawImage(image, 0, 0, null);
               //String newfilename = filename.substring(0,filename.lastIndexOf("."))+"_rgb"+filename.substring(filename.lastIndexOf("."));
               String newfilename = filename;
               File newFile = new File(newfilename);
               FileOutputStream out = new FileOutputStream(newFile);
               JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
               encoder.encode(image);
               out.flush();
               out.close();  
                
            }
        }

        private static BufferedImage createJPEG4(Raster raster) {
            int w = raster.getWidth();
            int h = raster.getHeight();
            byte[] rgb = new byte[w * h * 3];
          //彩色空间转换        
            float[] Y = raster.getSamples(0, 0, w, h, 0, (float[]) null);
            float[] Cb = raster.getSamples(0, 0, w, h, 1, (float[]) null);
            float[] Cr = raster.getSamples(0, 0, w, h, 2, (float[]) null);
            float[] K = raster.getSamples(0, 0, w, h, 3, (float[]) null);
            for (int i = 0, imax = Y.length, base = 0; i < imax; i++, base += 3) {
                float k = 220 - K[i], y = 255 - Y[i], cb = 255 - Cb[i],
                        cr = 255 - Cr[i];

                double val = y + 1.402 * (cr - 128) - k;
                val = (val - 128) * .65f + 128;
                rgb[base] = val < 0.0 ? (byte) 0 : val > 255.0 ? (byte) 0xff
                        : (byte) (val + 0.5);

                val = y - 0.34414 * (cb - 128) - 0.71414 * (cr - 128) - k;
                val = (val - 128) * .65f + 128;
                rgb[base + 1] = val < 0.0 ? (byte) 0 : val > 255.0 ? (byte) 0xff
                        : (byte) (val + 0.5);

                val = y + 1.772 * (cb - 128) - k;
                val = (val - 128) * .65f + 128;
                rgb[base + 2] = val < 0.0 ? (byte) 0 : val > 255.0 ? (byte) 0xff
                        : (byte) (val + 0.5);
            }
            raster = Raster.createInterleavedRaster(new DataBufferByte(rgb, rgb.length), w, h, w * 3, 3, new int[]{0, 1, 2}, null);
            ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_sRGB);
            ColorModel cm = new ComponentColorModel(cs, false, true, Transparency.OPAQUE, DataBuffer.TYPE_BYTE);
            return new BufferedImage(cm, (WritableRaster) raster, true, null);
        }
       //测试
       public static void main(String[] args) throws IOException { 
              String filename = "d:/2015.jpg";
              CMYK cm = new CMYK();
              cm.readImage(filename);
        } 

}