将CMYK彩色空间的图片转换为RGB彩色空间的图片

来源：互联网发布：阿里云外包编辑：程序博客网时间：2024/04/28 04:56

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。