CMYKColorSpace.java

/*
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

package com.sun.pdfview.colorspace;

import java.awt.color.ColorSpace;
import java.awt.color.ICC_ColorSpace;
import java.awt.color.ICC_Profile;
import java.io.IOException;

import com.sun.pdfview.BaseWatchable;

/**
 * A ColorSpace for the CMYK color space.
 *
 * Take from net.sf.jcgm.core.CMYKColorSpace.java
 * 
 * @author XOND
 * @version $Id: CMYKColorSpace.java,v 1.2 2011-01-06 12:12:21 xond Exp $
 */
public class CMYKColorSpace extends ColorSpace {

	private ICC_Profile icc;
	private ICC_ColorSpace icc_cs;
	
	/**
	 * Create a new CMYKColorSpace Instance.
	 */
	public CMYKColorSpace() {
		super(ColorSpace.TYPE_CMYK, 4);
		try {
			icc = ICC_Profile.getInstance(getClass().getResourceAsStream("/ch/randelshofer/media/jpeg/Generic_CMYK_Profile.icc"));
			icc_cs = new ICC_ColorSpace(icc);
		} catch (IOException e) {
		    BaseWatchable.getErrorHandler().publishException(e);
		}
	}

	/**
	 * Converts to CMYK from CIEXYZ. We cheat here, using the RGB colorspace
	 * to do the math for us. The toCIEXYZ function has a description of how
	 * this is supposed to work, which may be implemented in the future.
	 * 
	 * @see java.awt.color.ColorSpace#fromCIEXYZ(float[])
	 * @see org.scantegrity.lib.CMYKColorSpace#toCIEXYZ
	 */
	@Override
	public float[] fromCIEXYZ(float[] p_colorvalue) {
		if (icc_cs != null) {
			return icc_cs.fromCIEXYZ(p_colorvalue);
		}
		ColorSpace l_cs = ColorSpace.getInstance(ColorSpace.TYPE_RGB);
		float[] l_rgb = l_cs.toCIEXYZ(p_colorvalue);		
		return fromRGB(l_rgb);
	}

	/**
	 * Converts a given RGB to CMYK. RGB doesn't really use black, so K will 
	 * always be 0. On printers, the black should actually look dark brown.
	 * RGB (an additive space) is simply the backwards from CMY (a subtractive 
	 * space), so all we do is:
	 * 
	 * 		C = 1-R
	 * 		M = 1-G
	 * 		Y = 1-B
	 * 
	 * @param p_rgbvalue - The color to translate 
	 * @return a float[4] of the CMYK values.
	 * @see java.awt.color.ColorSpace#fromRGB(float[])
	 */
	@Override
	public float[] fromRGB(float[] p_rgbvalue) {
		if (icc_cs != null) {
			return icc_cs.fromRGB(p_rgbvalue);
		}

		/* TODO: Maybe we should do a better job to determine when black should 
		 * be used and pulled out? -- At this time, it's not necessary for our
		 * (Scantegrity's) uses.
		 */
		float[] l_res = {0,0,0,0};
		if (p_rgbvalue.length >= 3) {
			l_res[0] = (float)1.0 - p_rgbvalue[0];
			l_res[1] = (float)1.0 - p_rgbvalue[1];
			l_res[2] = (float)1.0 - p_rgbvalue[2];			
		}
		return normalize(l_res);
	}

	/** 
	 * Converts the CMYK color to CIEXYZ. Because CIEXYZ is 3-component, we 
	 * cheat, converting to RGB and then using the RGB colorspace function
	 * to do the conversion. Details on this colorspace are available on 
	 * wikipedia: 
	 * 
	 * http://en.wikipedia.org/wiki/CIE_XYZ_color_space
	 * 
	 * There is also an "ideal relationship" to CMYK, which might be implemented
	 * in the future (don't recall the reference we got this from, probably
	 * color.org):
	 * 
	 * C = (C' - K)/(1 - K)
	 * M = (M' - K)/(1 - K)
	 * Y = (Y' - K)/(1 - K)
	 * K = Min(C', M', Y')
	 * 
	 * X   41.2453 35.7580 18.0423 | 1-C'
	 * Y = 21.2671 71.5160 07.2169 | 1-M'
	 * Z   01.9334 11.9193 95.0227 | 1-Y'
	 * 
	 * @see java.awt.color.ColorSpace#toCIEXYZ(float[])
	 */
	@Override
	public float[] toCIEXYZ(float[] p_colorvalue) {
		if (icc_cs != null) {
			return icc_cs.toCIEXYZ(p_colorvalue);
		}

		float[] l_rgb = toRGB(p_colorvalue);
		ColorSpace l_cs = ColorSpace.getInstance(ColorSpace.TYPE_RGB);
		return l_cs.toCIEXYZ(l_rgb);
	}

	/**
	 * Converts CMYK colors to RGB. Note that converting back will be lossy. The
	 * formula for this is:
	 * 
	 * K = 1 - K (go to additive)
	 * R = K * (1 - C)
	 * G = K * (1 - M)
	 * B = K * (1 - Y)
	 * 
	 * @param p_colorvalue The color in CMYK.
	 * @see java.awt.color.ColorSpace#toRGB(float[])
	 */
	@Override
	public float[] toRGB(float[] p_colorvalue) {
		if (icc_cs != null) {
			return icc_cs.toRGB(p_colorvalue);
		}
		float[] l_res = {0,0,0};
		if (p_colorvalue.length >= 4)
		{
			float l_black = (float)1.0 - p_colorvalue[3]; 
			l_res[0] = l_black * ((float)1.0 - p_colorvalue[0]);
			l_res[1] = l_black * ((float)1.0 - p_colorvalue[1]);
			l_res[2] = l_black * ((float)1.0 - p_colorvalue[2]);			
		}
		return normalize(l_res);
	}
	
	/**
	 * Normalize ensures all color values returned are between 0 and 1.
	 * 
	 * @param p_colors
	 * @return p_colors, with any values greater than 1 set to 1, and less than
	 * 0 set to 0.
	 */
	public float[] normalize(float[] p_colors) {
		for (int l_i = 0; l_i < p_colors.length; l_i++) {
			if (p_colors[l_i] > (float)1.0) p_colors[l_i] = (float)1.0;
			else if (p_colors[l_i] < (float)0.0) p_colors[l_i] = (float)0.0;
		}		
		return p_colors;
	}
}