将CMYK彩色空间的图片转换为RGB彩色空间的图片

最近给网站(http://www.30buy.com/?source=2355)增加一个会员头像的功能,这就必然的会有用户上传图片然后压缩啊，剪裁啊 什么什么的。
做出来了，自己独自测试，通过了。然后交由老大验收，结果他在测试的时候，上传了一张比较大的jpg格式的图片，然后程序运行不通过了。我原本以为是图片太大导致，自己又重新测试，用了一张更大的图，通过了。这是为毛呢。然后看了看报错，Unsupport Image Type .度娘&谷哥后，原来是CMYK这么个东西，就是我自己测试的时候用的全是RGB的图片，老大测试的时候用的那张是CMYK的，然后就出现了这结果。 于是，继续度娘&谷哥，找到了一些将CMYK的图片转为RGB的源代码，COPY测试不通过。经过对几种方法的测试和"研究".ND
终于将这个问题搞定了。下面给出代码：

package com.test.common;

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;

/**

*

* @author Dsmart

*/

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("."));

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);

}

public static void main(String[] args) throws IOException

{

String filename = "h:/img/test.jpg";

CMYK cm = new CMYK();

cm.readImage(filename);

}

}

由于CMYK和RGB的不同，所以在转换后会出现颜色变亮。