Question

我需要将PNG文件转换为CMYK JPEG。

在我的研究过程中，我发现了多篇关于SO的文章来描述这个问题。我使用BufferedImage和ColorConvertOp复制了this answer。

我想出了这个小例子：

public static void main(final String[] args) throws IOException
{
    final String imageFile = "/tmp/page0.png";

    final BufferedImage pngImage = ImageIO.read(new File(imageFile));

    // convert PNG to JPEG
    // http://www.mkyong.com/java/convert-png-to-jpeg-image-file-in-java/
    final BufferedImage rgbImage = new BufferedImage(pngImage.getWidth(), pngImage.getHeight(), BufferedImage.TYPE_INT_RGB);
    rgbImage.createGraphics().drawImage(pngImage, 0, 0, Color.WHITE, null);

    // RGB to CMYK using ColorConvertOp
    // https://stackoverflow.com/questions/380678/how-to-set-icc-color-profile-in-java-and-change-colorspace/2804370#2804370
    final ICC_Profile ip = ICC_Profile.getInstance("icc/ISOcoated_v2_300_eci.icc");
    // final ICC_Profile ip = ICC_Profile.getInstance("icc/CoatedFOGRA27.icc");
    // final ICC_Profile ip = ICC_Profile.getInstance("icc/USWebUncoated.icc");

    final ColorConvertOp cco = new ColorConvertOp(new ICC_ColorSpace(ip), null);
    final BufferedImage cmykImage = cco.filter(rgbImage, null);

    // Write the result into an bytearray
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(cmykImage, "jpg", baos);
    baos.flush();

    final byte[] imageInByte = baos.toByteArray();
}

问题是，它引导我进入这个例外：

Exception in thread "main" javax.imageio.IIOException: Invalid argument to native writeImage
    at com.sun.imageio.plugins.jpeg.JPEGImageWriter.writeImage(Native Method)
    at com.sun.imageio.plugins.jpeg.JPEGImageWriter.writeOnThread(JPEGImageWriter.java:1058)
    at com.sun.imageio.plugins.jpeg.JPEGImageWriter.write(JPEGImageWriter.java:360)
    at javax.imageio.ImageWriter.write(ImageWriter.java:615)
    at javax.imageio.ImageIO.doWrite(ImageIO.java:1612)
    at javax.imageio.ImageIO.write(ImageIO.java:1578)
    at ... .pdf.ReportGeneratorPublicContentTest.main(ReportGeneratorPublicContentTest.java:69)

Exception的消息对我没有帮助。在this thread，他们说sun jdk或JAI将解决这个问题。

我尝试了apt-get install libjai-core-java和oracle JDK jdk1.7.0_51。错误仍然存在。

Answer 1

@Christian Schneider：下载带有CMYK JPEG链接的图像文件后，我打开文件的属性。我看到图像的色彩空间仍然是RGB。此图片未转换为CMYK颜色。请参阅以下链接：

how can I convert an RGB image to CMYK and vice versa in Java?

lovelywib的答案解决了这个问题。

Answer 2

使用TYPE_3BYTE_BGR代替TYPE_INT_RGB来解决问题。

public static void main(String[] args) throws Exception
{
    final String imageFile = "/tmp/page0.png";

    final BufferedImage pngImage = ImageIO.read(new File(imageFile));

    // convert PNG to JPEG
    // http://www.mkyong.com/java/convert-png-to-jpeg-image-file-in-java/
    final BufferedImage rgbImage = new BufferedImage(pngImage.getWidth(), pngImage.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
    rgbImage.createGraphics().drawImage(pngImage, 0, 0, Color.WHITE, null);

    // RGB to CMYK using ColorConvertOp
    // http://stackoverflow.com/questions/380678/how-to-set-icc-color-profile-in-java-and-change-colorspace/2804370#2804370
    final ICC_Profile ip = ICC_Profile.getInstance("icc/USWebUncoated.icc");

    final ColorConvertOp cco = new ColorConvertOp(rgbImage.getColorModel().getColorSpace(), new ICC_ColorSpace(ip), null);

    final BufferedImage cmykImage = new BufferedImage(pngImage.getWidth(), pngImage.getHeight(), BufferedImage.TYPE_3BYTE_BGR);

    cco.filter(rgbImage, cmykImage);

    // Write the result into an bytearray
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    ImageIO.write(cmykImage, "JPEG", baos);
    baos.flush();
}

将RGB PNG转换为CMYK JPEG（使用ICC颜色配置文件）

2 个答案: