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The Apache PDFBox library is an open source Java tool for working with PDF documents.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.pdfbox.pdmodel.graphics.color;
import org.apache.pdfbox.cos.COSArray;
import org.apache.pdfbox.cos.COSFloat;
import org.apache.pdfbox.cos.COSName;
import org.apache.pdfbox.pdmodel.common.PDRange;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.IOException;
/**
* A Lab colour space is a CIE-based ABC colour space with two transformation stages.
*
* @author Ben Litchfield
* @author John Hewson
*/
public final class PDLab extends PDCIEDictionaryBasedColorSpace
{
private PDColor initialColor;
/**
* Creates a new Lab color space.
*/
public PDLab()
{
super(COSName.LAB);
}
/**
* Creates a new Lab color space from a PDF array.
* @param lab the color space array
*/
public PDLab(COSArray lab)
{
super(lab);
}
@Override
public String getName()
{
return COSName.LAB.getName();
}
//
// WARNING: this method is performance sensitive, modify with care!
//
@Override
public BufferedImage toRGBImage(WritableRaster raster) throws IOException
{
int width = raster.getWidth();
int height = raster.getHeight();
BufferedImage rgbImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
WritableRaster rgbRaster = rgbImage.getRaster();
float minA = getARange().getMin();
float maxA = getARange().getMax();
float minB = getBRange().getMin();
float maxB = getBRange().getMax();
// always three components: ABC
float[] abc = new float[3];
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
raster.getPixel(x, y, abc);
// 0..255 -> 0..1
abc[0] /= 255;
abc[1] /= 255;
abc[2] /= 255;
// scale to range
abc[0] *= 100;
abc[1] = minA + (abc[1] * (maxA - minA));
abc[2] = minB + (abc[2] * (maxB - minB));
float[] rgb = toRGB(abc);
// 0..1 -> 0..255
rgb[0] *= 255;
rgb[1] *= 255;
rgb[2] *= 255;
rgbRaster.setPixel(x, y, rgb);
}
}
return rgbImage;
}
@Override
public float[] toRGB(float[] value)
{
// CIE LAB to RGB, see http://en.wikipedia.org/wiki/Lab_color_space
// L*
float lstar = (value[0] + 16f) * (1f / 116f);
// TODO: how to use the blackpoint? scale linearly between black & white?
// XYZ
float x = wpX * inverse(lstar + value[1] * (1f / 500f));
float y = wpY * inverse(lstar);
float z = wpZ * inverse(lstar - value[2] * (1f / 200f));
return convXYZtoRGB(x, y, z);
}
// reverse transformation (f^-1)
private float inverse(float x)
{
if (x > 6.0 / 29.0)
{
return x * x * x;
}
else
{
return (108f / 841f) * (x - (4f / 29f));
}
}
@Override
public int getNumberOfComponents()
{
return 3;
}
@Override
public float[] getDefaultDecode(int bitsPerComponent)
{
PDRange a = getARange();
PDRange b = getARange();
return new float[] { 0, 100, a.getMin(), a.getMax(), b.getMin(), b.getMax() };
}
@Override
public PDColor getInitialColor()
{
if (initialColor == null)
{
initialColor = new PDColor(new float[] {
0,
Math.max(0, getARange().getMin()),
Math.max(0, getBRange().getMin()) },
this);
}
return initialColor;
}
/**
* creates a range array with default values (-100..100 -100..100).
* @return the new range array.
*/
private COSArray getDefaultRangeArray()
{
COSArray range = new COSArray();
range.add(new COSFloat(-100));
range.add(new COSFloat(100));
range.add(new COSFloat(-100));
range.add(new COSFloat(100));
return range;
}
/**
* This will get the valid range for the "a" component.
* If none is found then the default will be returned, which is -100..100.
* @return the "a" range.
*/
public PDRange getARange()
{
COSArray rangeArray = (COSArray) dictionary.getDictionaryObject(COSName.RANGE);
if (rangeArray == null)
{
rangeArray = getDefaultRangeArray();
}
return new PDRange(rangeArray, 0);
}
/**
* This will get the valid range for the "b" component.
* If none is found then the default will be returned, which is -100..100.
* @return the "b" range.
*/
public PDRange getBRange()
{
COSArray rangeArray = (COSArray) dictionary.getDictionaryObject(COSName.RANGE);
if (rangeArray == null)
{
rangeArray = getDefaultRangeArray();
}
return new PDRange(rangeArray, 1);
}
/**
* This will set the a range for the "a" component.
* @param range the new range for the "a" component,
* or null if defaults (-100..100) are to be set.
*/
public void setARange(PDRange range)
{
setComponentRangeArray(range, 0);
}
/**
* This will set the "b" range for this color space.
* @param range the new range for the "b" component,
* or null if defaults (-100..100) are to be set.
*/
public void setBRange(PDRange range)
{
setComponentRangeArray(range, 2);
}
private void setComponentRangeArray(PDRange range, int index)
{
COSArray rangeArray = (COSArray) dictionary.getDictionaryObject(COSName.RANGE);
if (rangeArray == null)
{
rangeArray = getDefaultRangeArray();
}
if (range == null)
{
// reset to defaults
rangeArray.set(index, new COSFloat(-100));
rangeArray.set(index + 1, new COSFloat(100));
}
else
{
rangeArray.set(index, new COSFloat(range.getMin()));
rangeArray.set(index + 1, new COSFloat(range.getMax()));
}
dictionary.setItem(COSName.RANGE, rangeArray);
initialColor = null;
}
}