/*
* $Id: LabColor.java,v 1.2 2007-12-20 18:33:34 rbair Exp $
*
* 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.io.IOException;
import com.sun.pdfview.PDFObject;
/**
* A ColorSpace for Lab color
* @author Mike Wessler
*/
public class LabColor extends ColorSpace {
float white[]= {1f, 1f, 1f};
float black[]= {0, 0, 0};
float range[]= {-100f, 100f, -100f, 100f};
static ColorSpace cie= ColorSpace.getInstance(ColorSpace.CS_sRGB);
/**
* Create a new Lab color space object, given the description in
* a PDF dictionary.
* @param obj a dictionary that contains an Array of 3 Numbers for
* "WhitePoint" and "BlackPoint", and an array of 4 Numbers for
* "Range".
*/
public LabColor(PDFObject obj) throws IOException {
// obj is a dictionary that has the following parts:
// WhitePoint [a b c]
// BlackPoint [a b c]
// Gamma a
super(TYPE_Lab, 3);
PDFObject ary= obj.getDictRef("WhitePoint");
if (ary!=null) {
for(int i=0; i<3; i++) {
white[i]= ary.getAt(i).getFloatValue();
}
}
ary= obj.getDictRef("BlackPoint");
if (ary!=null) {
for(int i=0; i<3; i++) {
black[i]= ary.getAt(i).getFloatValue();
}
}
ary= obj.getDictRef("Range");
if (ary!=null) {
for (int i=0; i<4; i++) {
range[i]= ary.getAt(i).getFloatValue();
}
}
}
/**
* get the number of components for this color space (3)
*/
@Override public int getNumComponents() {
return 3;
}
/**
* Stage 2 of the conversion algorithm. Pulled out because
* it gets invoked for each component
*/
public final float stage2(float s1) {
return (s1>=6f/29f)?s1*s1*s1:108f/841f*(s1-4f/29f);
}
/**
* convert from Lab to RGB
* @param comp the Lab values (0-1)
* @return the RGB values (0-1)
*/
public float[] toRGB(float comp[]) {
if (comp.length==3) {
float l= (comp[0]+16)/116+comp[1]/500;
float m= (comp[0]+16)/116;
float n= (comp[0]+16)/116-comp[2]/200;
float xyz[]= {
white[0]*stage2(l),
white[0]*stage2(m),
white[0]*stage2(n)};
float rgb[]= cie.fromCIEXYZ(xyz);
return rgb;
} else {
return black;
}
}
/**
* convert from RGB to Lab. NOT IMPLEMENTED
*/
public float[] fromRGB(float[] rgbvalue) {
return new float[3];
}
/**
* convert from CIEXYZ to Lab. NOT IMPLEMENTED
*/
public float[] fromCIEXYZ(float[] colorvalue) {
return new float[3];
}
/**
* get the type of this colorspace (TYPE_Lab)
*/
@Override public int getType() {
return TYPE_Lab;
}
/**
* convert from Lab to CIEXYZ. NOT IMPLEMENTED
*/
public float[] toCIEXYZ(float[] colorvalue) {
return new float[3];
}
}