問題描述

我需要將圖像從 CMYK 轉(zhuǎn)換為 RGB - 不一定要再轉(zhuǎn)換回來，但是嘿，如果可以的話...

I have a need to convert images from CMYK to RGB - not necessarily back again, but hey, if it can be done...

隨著 ColdFusion 8 的發(fā)布，我們獲得了 CFImage 標(biāo)簽，但它沒有'不支持這種轉(zhuǎn)換；Image.cfc 或 Alagad 的圖像組件.

With the release of ColdFusion 8, we got the CFImage tag, but it doesn't support this conversion; and nor does Image.cfc, or Alagad's Image Component.

但是，在 Java 中應(yīng)該是可能的；我們可以通過 CF 加以利用.例如，以下是創(chuàng)建 Java 線程來休眠進(jìn)程的方法:

However, it should be possible in Java; which we can leverage through CF. For example, here's how you might create a Java thread to sleep a process:

<cfset jthread = createObject("java", "java.lang.Thread")/>
<cfset jthread.sleep(5000)/>

我猜想可以使用類似的方法來利用 java 進(jìn)行這種圖像轉(zhuǎn)換，但不是 Java 開發(fā)人員，我不知道從哪里開始.有人可以幫忙嗎?

I would guess a similar method could be used to leverage java to do this image conversion, but not being a Java developer, I don't have a clue where to start. Can anyone lend a hand here?

推薦答案

我使用 Java ImageIO 庫 (https://jai-imageio.dev.java.net).它們并不完美，但可以很簡單并完成工作.至于從 CMYK 轉(zhuǎn)換為 RGB，這是我能想到的最好的.

I use the Java ImageIO libraries (https://jai-imageio.dev.java.net). They aren't perfect, but can be simple and get the job done. As far as converting from CMYK to RGB, here is the best I have been able to come up with.

為您的平臺下載并安裝 ImageIO JAR 和本機(jī)庫.本機(jī)庫是必不可少的.沒有它們，ImageIO JAR 文件將無法檢測 CMYK 圖像.最初，我的印象是本機(jī)庫會提高性能，但不需要任何功能.我錯了.

Download and install the ImageIO JARs and native libraries for your platform. The native libraries are essential. Without them the ImageIO JAR files will not be able to detect the CMYK images. Originally, I was under the impression that the native libraries would improve performance but was not required for any functionality. I was wrong.

我注意到的另一件事是，轉(zhuǎn)換后的 RGB 圖像有時比 CMYK 圖像輕得多.如果有人知道如何解決這個問題，我將不勝感激.

The only other thing that I noticed is that the converted RGB images are sometimes much lighter than the CMYK images. If anyone knows how to solve that problem, I would be appreciative.

以下是將 CMYK 圖像轉(zhuǎn)換為任何支持格式的 RGB 圖像的一些代碼.

Below is some code to convert a CMYK image into an RGB image of any supported format.

謝謝你，
蘭迪·施泰格鮑爾

Thank you,
Randy Stegbauer

package cmyk;

import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

import org.apache.commons.lang.StringUtils;

public class Main
{

    /**
     * Creates new RGB images from all the CMYK images passed
     * in on the command line.
     * The new filename generated is, for example "GIF_original_filename.gif".
     *
     */
    public static void main(String[] args)
    {
        for (int ii = 0; ii < args.length; ii++)
        {
            String filename = args[ii];
            boolean cmyk = isCMYK(filename);
            System.out.println(cmyk + ": " + filename);
            if (cmyk)
            {
                try
                {
                    String rgbFile = cmyk2rgb(filename);
                    System.out.println(isCMYK(rgbFile) + ": " + rgbFile);
                }
                catch (IOException e)
                {
                    System.out.println(e.getMessage());
                }
            }
        }
    }

    /**
     * If 'filename' is a CMYK file, then convert the image into RGB,
     * store it into a JPEG file, and return the new filename.
     *
     * @param filename
     */
    private static String cmyk2rgb(String filename) throws IOException
    {
        // Change this format into any ImageIO supported format.
        String format = "gif";
        File imageFile = new File(filename);
        String rgbFilename = filename;
        BufferedImage image = ImageIO.read(imageFile);
        if (image != null)
        {
            int colorSpaceType = image.getColorModel().getColorSpace().getType();
            if (colorSpaceType == ColorSpace.TYPE_CMYK)
            {
                BufferedImage rgbImage =
                    new BufferedImage(
                        image.getWidth(), image.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
                ColorConvertOp op = new ColorConvertOp(null);
                op.filter(image, rgbImage);

                rgbFilename = changeExtension(imageFile.getName(), format);
                rgbFilename = new File(imageFile.getParent(), format + "_" + rgbFilename).getPath();
                ImageIO.write(rgbImage, format, new File(rgbFilename));
            }
        }
        return rgbFilename;
    }

    /**
     * Change the extension of 'filename' to 'newExtension'.
     *
     * @param filename
     * @param newExtension
     * @return filename with new extension
     */
    private static String changeExtension(String filename, String newExtension)
    {
        String result = filename;
        if (filename != null && newExtension != null && newExtension.length() != 0);
        {
            int dot = filename.lastIndexOf('.');
            if (dot != -1)
            {
                result = filename.substring(0, dot) + '.' + newExtension;
            }
        }
        return result;
    }

    private static boolean isCMYK(String filename)
    {
        boolean result = false;
        BufferedImage img = null;
        try
        {
            img = ImageIO.read(new File(filename));
        }
        catch (IOException e)
        {
            System.out.println(e.getMessage() + ": " + filename);
        }
        if (img != null)
        {
            int colorSpaceType = img.getColorModel().getColorSpace().getType();
            result = colorSpaceType == ColorSpace.TYPE_CMYK;
        }

        return result;
    }
}

這篇關(guān)于如何在 ColdFusion (Java) 中在 CMYK 和 RGB 之間轉(zhuǎn)換圖像?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！