001/*
002 * $RCSfile: TIFFYCbCrColorConverter.java,v $
003 *
004 * 
005 * Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
006 * 
007 * Redistribution and use in source and binary forms, with or without
008 * modification, are permitted provided that the following conditions
009 * are met: 
010 * 
011 * - Redistribution of source code must retain the above copyright 
012 *   notice, this  list of conditions and the following disclaimer.
013 * 
014 * - Redistribution in binary form must reproduce the above copyright
015 *   notice, this list of conditions and the following disclaimer in 
016 *   the documentation and/or other materials provided with the
017 *   distribution.
018 * 
019 * Neither the name of Sun Microsystems, Inc. or the names of 
020 * contributors may be used to endorse or promote products derived 
021 * from this software without specific prior written permission.
022 * 
023 * This software is provided "AS IS," without a warranty of any 
024 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
025 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
026 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
027 * EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL 
028 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF 
029 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
030 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR 
031 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
032 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
033 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
034 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
035 * POSSIBILITY OF SUCH DAMAGES. 
036 * 
037 * You acknowledge that this software is not designed or intended for 
038 * use in the design, construction, operation or maintenance of any 
039 * nuclear facility. 
040 *
041 * $Revision: 1.2 $
042 * $Date: 2006/04/11 22:10:37 $
043 * $State: Exp $
044 */
045package com.github.jaiimageio.impl.plugins.tiff;
046
047import java.awt.color.ColorSpace;
048
049import com.github.jaiimageio.plugins.tiff.BaselineTIFFTagSet;
050import com.github.jaiimageio.plugins.tiff.TIFFColorConverter;
051import com.github.jaiimageio.plugins.tiff.TIFFField;
052
053/**
054 */
055public class TIFFYCbCrColorConverter extends TIFFColorConverter {
056
057    private float LumaRed = 0.299f;
058    private float LumaGreen = 0.587f;
059    private float LumaBlue = 0.114f;
060
061    private float referenceBlackY = 0.0f;
062    private float referenceWhiteY = 255.0f;
063
064    private float referenceBlackCb = 128.0f;
065    private float referenceWhiteCb = 255.0f;
066
067    private float referenceBlackCr = 128.0f;
068    private float referenceWhiteCr = 255.0f;
069
070    private float codingRangeY = 255.0f;
071    private float codingRangeCbCr = 127.0f;
072
073    public TIFFYCbCrColorConverter(TIFFImageMetadata metadata) {
074        TIFFImageMetadata tmetadata = (TIFFImageMetadata)metadata;
075
076        TIFFField f =
077           tmetadata.getTIFFField(BaselineTIFFTagSet.TAG_Y_CB_CR_COEFFICIENTS);
078        if (f != null && f.getCount() == 3) {
079            this.LumaRed = f.getAsFloat(0);
080            this.LumaGreen = f.getAsFloat(1);
081            this.LumaBlue = f.getAsFloat(2);
082        }
083
084        f =
085          tmetadata.getTIFFField(BaselineTIFFTagSet.TAG_REFERENCE_BLACK_WHITE);
086        if (f != null && f.getCount() == 6) {
087            this.referenceBlackY = f.getAsFloat(0);
088            this.referenceWhiteY = f.getAsFloat(1);
089            this.referenceBlackCb = f.getAsFloat(2);
090            this.referenceWhiteCb = f.getAsFloat(3);
091            this.referenceBlackCr = f.getAsFloat(4);
092            this.referenceWhiteCr = f.getAsFloat(5);
093        }
094    }
095
096    /*
097      The full range component value is converted from the code by:
098
099      FullRangeValue = (code - ReferenceBlack) * CodingRange
100                / (ReferenceWhite - ReferenceBlack);
101
102      The code is converted from the full-range component value by:
103
104      code = (FullRangeValue * (ReferenceWhite - ReferenceBlack)
105                / CodingRange) + ReferenceBlack;
106
107     */
108    public void fromRGB(float r, float g, float b, float[] result) {
109        // Convert RGB to full-range YCbCr.
110        float Y = (LumaRed*r + LumaGreen*g + LumaBlue*b);
111        float Cb = (b - Y)/(2 - 2*LumaBlue);
112        float Cr = (r - Y)/(2 - 2*LumaRed);
113
114        // Convert full-range YCbCr to code.
115        result[0] = Y*(referenceWhiteY - referenceBlackY)/codingRangeY +
116            referenceBlackY;
117        result[1] = Cb*(referenceWhiteCb - referenceBlackCb)/codingRangeCbCr +
118            referenceBlackCb;
119        result[2] = Cr*(referenceWhiteCr - referenceBlackCr)/codingRangeCbCr +
120            referenceBlackCr;
121    }
122
123    public void toRGB(float x0, float x1, float x2, float[] rgb) {
124        // Convert YCbCr code to full-range YCbCr.
125        float Y = (x0 - referenceBlackY)*codingRangeY/
126            (referenceWhiteY - referenceBlackY);
127        float Cb = (x1 - referenceBlackCb)*codingRangeCbCr/
128            (referenceWhiteCb - referenceBlackCb);
129        float Cr = (x2 - referenceBlackCr)*codingRangeCbCr/
130            (referenceWhiteCr - referenceBlackCr);
131
132        // Convert YCbCr to RGB.
133        rgb[0] = Cr*(2 - 2*LumaRed) + Y;
134        rgb[2] = Cb*(2 - 2*LumaBlue) + Y;
135        rgb[1] = (Y - LumaBlue*rgb[2] - LumaRed*rgb[0])/LumaGreen;
136    }
137}