src/main/java/org/apache/pdfbox/jbig2/segments/HalftoneRegion.java - pdfbox-jbig2 - Git at Google

 /**
  * 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.jbig2.segments;

 import java.io.IOException;
 import java.util.ArrayList;

 import org.apache.pdfbox.jbig2.Bitmap;
 import org.apache.pdfbox.jbig2.Region;
 import org.apache.pdfbox.jbig2.SegmentHeader;
 import org.apache.pdfbox.jbig2.err.InvalidHeaderValueException;
 import org.apache.pdfbox.jbig2.image.Bitmaps;
 import org.apache.pdfbox.jbig2.io.SubInputStream;
 import org.apache.pdfbox.jbig2.util.CombinationOperator;

 /**
  * This class represents the data of segment type "Halftone region". Parsing is described in 7.4.5, page 67. Decoding
  * procedure in 6.6.5 and 7.4.5.2.
  */
 public class HalftoneRegion implements Region
 {

     private SubInputStream subInputStream;
     private SegmentHeader segmentHeader;
     private long dataHeaderOffset;
     private long dataHeaderLength;
     private long dataOffset;
     private long dataLength;

     /** Region segment information field, 7.4.1 */
     private RegionSegmentInformation regionInfo;

     /** Halftone segment information field, 7.4.5.1.1 */
     private byte hDefaultPixel;
     private CombinationOperator hCombinationOperator;
     private boolean hSkipEnabled;
     private byte hTemplate;
     private boolean isMMREncoded;

     /** Halftone grid position and size, 7.4.5.1.2 */
     /** Width of the gray-scale image, 7.4.5.1.2.1 */
     private int hGridWidth;
     /** Height of the gray-scale image, 7.4.5.1.2.2 */
     private int hGridHeight;
     /** Horizontal offset of the grid, 7.4.5.1.2.3 */
     private int hGridX;
     /** Vertical offset of the grid, 7.4.5.1.2.4 */
     private int hGridY;

     /** Halftone grid vector, 7.4.5.1.3 */
     /** Horizontal coordinate of the halftone grid vector, 7.4.5.1.3.1 */
     private int hRegionX;
     /** Vertical coordinate of the halftone grod vector, 7.4.5.1.3.2 */
     private int hRegionY;

     /** Decoded data */
     private Bitmap halftoneRegionBitmap;

     /**
      * Previously decoded data from other regions or dictionaries, stored to use as patterns in this region.
      */
     private ArrayList<Bitmap> patterns; // HPATS

     public HalftoneRegion()
     {
     }

     public HalftoneRegion(final SubInputStream subInputStream)
     {
         this.subInputStream = subInputStream;
         this.regionInfo = new RegionSegmentInformation(subInputStream);
     }

     public HalftoneRegion(final SubInputStream subInputStream, final SegmentHeader segmentHeader)
     {
         this.subInputStream = subInputStream;
         this.segmentHeader = segmentHeader;
         this.regionInfo = new RegionSegmentInformation(subInputStream);
     }

     private void parseHeader() throws IOException, InvalidHeaderValueException
     {
         regionInfo.parseHeader();

         // 7.4.5.1.1 Halftone region segment flags

         /* Bit 7: HDEFPIXEL */
         hDefaultPixel = (byte) subInputStream.readBit();

         /* Bit 4-6: HCOMBOP */
         hCombinationOperator = CombinationOperator
                 .translateOperatorCodeToEnum((short) (subInputStream.readBits(3) & 0xf));

         /* Bit 3: HENABLESKIP */
         if (subInputStream.readBit() == 1)
         {
             hSkipEnabled = true;
         }

         /* Bit 1-2: HTEMPLATE */
         hTemplate = (byte) (subInputStream.readBits(2) & 0xf);

         /* Bit 0: HMMR */
         if (subInputStream.readBit() == 1)
         {
             isMMREncoded = true;
         }

         // 7.4.5.1.2 Halftone grid position and size
         hGridWidth = (int) (subInputStream.readBits(32) & 0xffffffff); // HGW
         hGridHeight = (int) (subInputStream.readBits(32) & 0xffffffff); // HGH

         hGridX = (int) subInputStream.readBits(32); // HGX
         hGridY = (int) subInputStream.readBits(32); // HGY

         // 7.4.5.1.3 Halftone grid vector
         hRegionX = (int) subInputStream.readBits(16) & 0xffff; // HRX
         hRegionY = (int) subInputStream.readBits(16) & 0xffff; // HRY

         /* Segment data structure */
         computeSegmentDataStructure();
     }

     private void computeSegmentDataStructure() throws IOException
     {
         dataOffset = subInputStream.getStreamPosition();
         dataHeaderLength = dataOffset - dataHeaderOffset;
         dataLength = subInputStream.length() - dataHeaderLength;
     }

     /**
      * The procedure is described in JBIG2 ISO standard, 6.6.5.
      *
      * @return The decoded {@link Bitmap} of this region.
      *
      * @throws IOException if an underlying IO operation fails
      * @throws InvalidHeaderValueException if a segment header value is invalid
      */
     public Bitmap getRegionBitmap() throws IOException, InvalidHeaderValueException
     {
         if (null == halftoneRegionBitmap)
         {

             /* 6.6.5, page 40 */
             /* 1) */
             halftoneRegionBitmap = new Bitmap(regionInfo.getBitmapWidth(),
                     regionInfo.getBitmapHeight());

             if (patterns == null)
             {
                 patterns = getPatterns();
             }

             if (hDefaultPixel == 1)
             {
                 halftoneRegionBitmap.fillBitmap((byte) 0xff);
             }

             /* 2) 6.6.5.1 Computing HSKIP */

             Bitmap hSkip = null;
             if (hSkipEnabled)
             {
                 int hPatternHeight = (int) patterns.get(0).getHeight(); // HPW
                 int hPatternWidth = (int) patterns.get(0).getWidth(); // HPH
                 hSkip = computeHSkip(hPatternWidth, hPatternHeight);
             }

             /* 3) */
             final int bitsPerValue = (int) Math.ceil(Math.log(patterns.size()) / Math.log(2));

             /* 4) */
             final int[][] grayScaleValues = grayScaleDecoding(bitsPerValue, hSkip);

             /* 5), rendering the pattern, described in 6.6.5.2 */
             renderPattern(grayScaleValues);
         }
         /* 6) */
         return halftoneRegionBitmap;
     }

     /**
      * This method draws the pattern into the region bitmap ({@code htReg}), as described in 6.6.5.2, page 42
      */
     private void renderPattern(final int[][] grayScaleValues)
     {
         int x = 0, y = 0;

         // 1)
         for (int m = 0; m < hGridHeight; m++)
         {
             // a)
             for (int n = 0; n < hGridWidth; n++)
             {
                 // i)
                 x = computeX(m, n);
                 y = computeY(m, n);

                 // ii)
                 final Bitmap patternBitmap = patterns.get(grayScaleValues[m][n]);
                 Bitmaps.blit(patternBitmap, halftoneRegionBitmap, x, y,
                         hCombinationOperator);
             }
         }
     }

     /**
      * @throws IOException
      * @throws InvalidHeaderValueException
      *
      */
     private ArrayList<Bitmap> getPatterns() throws InvalidHeaderValueException, IOException
     {
         final ArrayList<Bitmap> patterns = new ArrayList<Bitmap>();

         for (SegmentHeader s : segmentHeader.getRtSegments())
         {
             final PatternDictionary patternDictionary = (PatternDictionary) s.getSegmentData();
             patterns.addAll(patternDictionary.getDictionary());
         }

         return patterns;
     }

     /**
      * Gray-scale image decoding procedure is special for halftone region decoding and is described in Annex C.5 on page
      * 98.
      */
     private int[][] grayScaleDecoding(final int bitsPerValue, final Bitmap hSkip) throws IOException
     {

         short[] gbAtX = null;
         short[] gbAtY = null;

         if (!isMMREncoded)
         {
             gbAtX = new short[4];
             gbAtY = new short[4];
             // Set AT pixel values
             if (hTemplate <= 1)
                 gbAtX[0] = 3;
             else if (hTemplate >= 2)
                 gbAtX[0] = 2;

             gbAtY[0] = -1;
             gbAtX[1] = -3;
             gbAtY[1] = -1;
             gbAtX[2] = 2;
             gbAtY[2] = -2;
             gbAtX[3] = -2;
             gbAtY[3] = -2;
         }

         Bitmap[] grayScalePlanes = new Bitmap[bitsPerValue];

         // 1)
         GenericRegion genericRegion = new GenericRegion(subInputStream);
         genericRegion.setParameters(isMMREncoded, dataOffset, dataLength, hGridHeight, hGridWidth,
                 hTemplate, false, hSkipEnabled, hSkip, gbAtX, gbAtY);

         // 2)
         int j = bitsPerValue - 1;

         grayScalePlanes[j] = genericRegion.getRegionBitmap();

         while (j > 0)
         {
             j--;
             genericRegion.resetBitmap();
             // 3) a)
             grayScalePlanes[j] = genericRegion.getRegionBitmap();
             // 3) b)
             grayScalePlanes = combineGrayScalePlanes(grayScalePlanes, j);
         }

         // 4)
         return computeGrayScaleValues(grayScalePlanes, bitsPerValue);
     }

     private Bitmap[] combineGrayScalePlanes(Bitmap[] grayScalePlanes, int j)
     {
         int byteIndex = 0;
         for (int y = 0; y < grayScalePlanes[j].getHeight(); y++)
         {

             for (int x = 0; x < grayScalePlanes[j].getWidth(); x += 8)
             {
                 final byte newValue = grayScalePlanes[j + 1].getByte(byteIndex);
                 final byte oldValue = grayScalePlanes[j].getByte(byteIndex);

                 grayScalePlanes[j].setByte(byteIndex++,
                         Bitmaps.combineBytes(oldValue, newValue, CombinationOperator.XOR));
             }
         }
         return grayScalePlanes;
     }

     private int[][] computeGrayScaleValues(final Bitmap[] grayScalePlanes, final int bitsPerValue)
     {
         // Gray-scale decoding procedure, page 98
         final int[][] grayScaleValues = new int[hGridHeight][hGridWidth];

         // 4)
         for (int y = 0; y < hGridHeight; y++)
         {
             for (int x = 0; x < hGridWidth; x += 8)
             {
                 final int minorWidth = hGridWidth - x > 8 ? 8 : hGridWidth - x;
                 int byteIndex = grayScalePlanes[0].getByteIndex(x, y);

                 for (int minorX = 0; minorX < minorWidth; minorX++)
                 {
                     final int i = minorX + x;
                     grayScaleValues[y][i] = 0;

                     for (int j = 0; j < bitsPerValue; j++)
                     {
                         grayScaleValues[y][i] += ((grayScalePlanes[j]
                                 .getByte(byteIndex) >> (7 - i & 7)) & 1) * (1 << j);
                     }
                 }
             }
         }
         return grayScaleValues;
     }

     private int computeX(final int m, final int n)
     {
         return (hGridX + m * hRegionY + n * hRegionX) >> 8;
     }

     private int computeY(final int m, final int n)
     {
         return (hGridY + m * hRegionX - n * hRegionY) >> 8;
     }

     public void init(final SegmentHeader header, final SubInputStream sis)
             throws InvalidHeaderValueException, IOException
     {
         this.segmentHeader = header;
         this.subInputStream = sis;
         this.regionInfo = new RegionSegmentInformation(subInputStream);
         parseHeader();
     }

     public CombinationOperator getCombinationOperator()
     {
         return hCombinationOperator;
     }

     public RegionSegmentInformation getRegionInfo()
     {
         return regionInfo;
     }

     protected byte getHTemplate()
     {
         return hTemplate;
     }

     protected boolean isHSkipEnabled()
     {
         return hSkipEnabled;
     }

     protected boolean isMMREncoded()
     {
         return isMMREncoded;
     }

     protected int getHGridWidth()
     {
         return hGridWidth;
     }

     protected int getHGridHeight()
     {
         return hGridHeight;
     }

     protected int getHGridX()
     {
         return hGridX;
     }

     protected int getHGridY()
     {
         return hGridY;
     }

     protected int getHRegionX()
     {
         return hRegionX;
     }

     protected int getHRegionY()
     {
         return hRegionY;
     }

     protected byte getHDefaultPixel()
     {
         return hDefaultPixel;
     }

     // 6.6.5.1 Computing HSKIP
     private Bitmap computeHSkip(int hPatternWidth, int hPatternHeight) throws IOException
     {
         Bitmap bitmap = new Bitmap(hGridWidth, hGridHeight); // HSKIP is HGW by HGH pixels
         for (int m = 0; m < hGridHeight; ++m)
         {
             for (int n = 0; n < hGridWidth; ++n)
             {
                 int x = computeX(m, n);
                 int y = computeY(m, n);
                 // HBW = halftoneRegionBitmap.getWidth()
                 // HBH = halftoneRegionBitmap.getHeight()
                 if (x + hPatternWidth <= 0 || x >= halftoneRegionBitmap.getWidth() || y + hPatternHeight <= 0 || y >= halftoneRegionBitmap.getHeight())
                 {
                     bitmap.setPixel(n, m, (byte) 1);
                 }
                 // else no need to set 0 pixels
             }
         }
         return bitmap;
     }
 }
	/**
	* 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.jbig2.segments;

	import java.io.IOException;
	import java.util.ArrayList;

	import org.apache.pdfbox.jbig2.Bitmap;
	import org.apache.pdfbox.jbig2.Region;
	import org.apache.pdfbox.jbig2.SegmentHeader;
	import org.apache.pdfbox.jbig2.err.InvalidHeaderValueException;
	import org.apache.pdfbox.jbig2.image.Bitmaps;
	import org.apache.pdfbox.jbig2.io.SubInputStream;
	import org.apache.pdfbox.jbig2.util.CombinationOperator;

	/**
	* This class represents the data of segment type "Halftone region". Parsing is described in 7.4.5, page 67. Decoding
	* procedure in 6.6.5 and 7.4.5.2.
	*/
	public class HalftoneRegion implements Region
	{

	private SubInputStream subInputStream;
	private SegmentHeader segmentHeader;
	private long dataHeaderOffset;
	private long dataHeaderLength;
	private long dataOffset;
	private long dataLength;

	/** Region segment information field, 7.4.1 */
	private RegionSegmentInformation regionInfo;

	/** Halftone segment information field, 7.4.5.1.1 */
	private byte hDefaultPixel;
	private CombinationOperator hCombinationOperator;
	private boolean hSkipEnabled;
	private byte hTemplate;
	private boolean isMMREncoded;

	/** Halftone grid position and size, 7.4.5.1.2 */
	/** Width of the gray-scale image, 7.4.5.1.2.1 */
	private int hGridWidth;
	/** Height of the gray-scale image, 7.4.5.1.2.2 */
	private int hGridHeight;
	/** Horizontal offset of the grid, 7.4.5.1.2.3 */
	private int hGridX;
	/** Vertical offset of the grid, 7.4.5.1.2.4 */
	private int hGridY;

	/** Halftone grid vector, 7.4.5.1.3 */
	/** Horizontal coordinate of the halftone grid vector, 7.4.5.1.3.1 */
	private int hRegionX;
	/** Vertical coordinate of the halftone grod vector, 7.4.5.1.3.2 */
	private int hRegionY;

	/** Decoded data */
	private Bitmap halftoneRegionBitmap;

	/**
	* Previously decoded data from other regions or dictionaries, stored to use as patterns in this region.
	*/
	private ArrayList<Bitmap> patterns; // HPATS

	public HalftoneRegion()
	{
	}

	public HalftoneRegion(final SubInputStream subInputStream)
	{
	this.subInputStream = subInputStream;
	this.regionInfo = new RegionSegmentInformation(subInputStream);
	}

	public HalftoneRegion(final SubInputStream subInputStream, final SegmentHeader segmentHeader)
	{
	this.subInputStream = subInputStream;
	this.segmentHeader = segmentHeader;
	this.regionInfo = new RegionSegmentInformation(subInputStream);
	}

	private void parseHeader() throws IOException, InvalidHeaderValueException
	{
	regionInfo.parseHeader();

	// 7.4.5.1.1 Halftone region segment flags

	/* Bit 7: HDEFPIXEL */
	hDefaultPixel = (byte) subInputStream.readBit();

	/* Bit 4-6: HCOMBOP */
	hCombinationOperator = CombinationOperator
	.translateOperatorCodeToEnum((short) (subInputStream.readBits(3) & 0xf));

	/* Bit 3: HENABLESKIP */
	if (subInputStream.readBit() == 1)
	{
	hSkipEnabled = true;
	}

	/* Bit 1-2: HTEMPLATE */
	hTemplate = (byte) (subInputStream.readBits(2) & 0xf);

	/* Bit 0: HMMR */
	if (subInputStream.readBit() == 1)
	{
	isMMREncoded = true;
	}

	// 7.4.5.1.2 Halftone grid position and size
	hGridWidth = (int) (subInputStream.readBits(32) & 0xffffffff); // HGW
	hGridHeight = (int) (subInputStream.readBits(32) & 0xffffffff); // HGH

	hGridX = (int) subInputStream.readBits(32); // HGX
	hGridY = (int) subInputStream.readBits(32); // HGY

	// 7.4.5.1.3 Halftone grid vector
	hRegionX = (int) subInputStream.readBits(16) & 0xffff; // HRX
	hRegionY = (int) subInputStream.readBits(16) & 0xffff; // HRY

	/* Segment data structure */
	computeSegmentDataStructure();
	}

	private void computeSegmentDataStructure() throws IOException
	{
	dataOffset = subInputStream.getStreamPosition();
	dataHeaderLength = dataOffset - dataHeaderOffset;
	dataLength = subInputStream.length() - dataHeaderLength;
	}

	/**
	* The procedure is described in JBIG2 ISO standard, 6.6.5.
	*
	* @return The decoded {@link Bitmap} of this region.
	*
	* @throws IOException if an underlying IO operation fails
	* @throws InvalidHeaderValueException if a segment header value is invalid
	*/
	public Bitmap getRegionBitmap() throws IOException, InvalidHeaderValueException
	{
	if (null == halftoneRegionBitmap)
	{

	/* 6.6.5, page 40 */
	/* 1) */
	halftoneRegionBitmap = new Bitmap(regionInfo.getBitmapWidth(),
	regionInfo.getBitmapHeight());

	if (patterns == null)
	{
	patterns = getPatterns();
	}

	if (hDefaultPixel == 1)
	{
	halftoneRegionBitmap.fillBitmap((byte) 0xff);
	}

	/* 2) 6.6.5.1 Computing HSKIP */

	Bitmap hSkip = null;
	if (hSkipEnabled)
	{
	int hPatternHeight = (int) patterns.get(0).getHeight(); // HPW
	int hPatternWidth = (int) patterns.get(0).getWidth(); // HPH
	hSkip = computeHSkip(hPatternWidth, hPatternHeight);
	}

	/* 3) */
	final int bitsPerValue = (int) Math.ceil(Math.log(patterns.size()) / Math.log(2));

	/* 4) */
	final int[][] grayScaleValues = grayScaleDecoding(bitsPerValue, hSkip);

	/* 5), rendering the pattern, described in 6.6.5.2 */
	renderPattern(grayScaleValues);
	}
	/* 6) */
	return halftoneRegionBitmap;
	}

	/**
	* This method draws the pattern into the region bitmap ({@code htReg}), as described in 6.6.5.2, page 42
	*/
	private void renderPattern(final int[][] grayScaleValues)
	{
	int x = 0, y = 0;

	// 1)
	for (int m = 0; m < hGridHeight; m++)
	{
	// a)
	for (int n = 0; n < hGridWidth; n++)
	{
	// i)
	x = computeX(m, n);
	y = computeY(m, n);

	// ii)
	final Bitmap patternBitmap = patterns.get(grayScaleValues[m][n]);
	Bitmaps.blit(patternBitmap, halftoneRegionBitmap, x, y,
	hCombinationOperator);
	}
	}
	}

	/**
	* @throws IOException
	* @throws InvalidHeaderValueException
	*
	*/
	private ArrayList<Bitmap> getPatterns() throws InvalidHeaderValueException, IOException
	{
	final ArrayList<Bitmap> patterns = new ArrayList<Bitmap>();

	for (SegmentHeader s : segmentHeader.getRtSegments())
	{
	final PatternDictionary patternDictionary = (PatternDictionary) s.getSegmentData();
	patterns.addAll(patternDictionary.getDictionary());
	}

	return patterns;
	}

	/**
	* Gray-scale image decoding procedure is special for halftone region decoding and is described in Annex C.5 on page
	* 98.
	*/
	private int[][] grayScaleDecoding(final int bitsPerValue, final Bitmap hSkip) throws IOException
	{

	short[] gbAtX = null;
	short[] gbAtY = null;

	if (!isMMREncoded)
	{
	gbAtX = new short[4];
	gbAtY = new short[4];
	// Set AT pixel values
	if (hTemplate <= 1)
	gbAtX[0] = 3;
	else if (hTemplate >= 2)
	gbAtX[0] = 2;

	gbAtY[0] = -1;
	gbAtX[1] = -3;
	gbAtY[1] = -1;
	gbAtX[2] = 2;
	gbAtY[2] = -2;
	gbAtX[3] = -2;
	gbAtY[3] = -2;
	}

	Bitmap[] grayScalePlanes = new Bitmap[bitsPerValue];

	// 1)
	GenericRegion genericRegion = new GenericRegion(subInputStream);
	genericRegion.setParameters(isMMREncoded, dataOffset, dataLength, hGridHeight, hGridWidth,
	hTemplate, false, hSkipEnabled, hSkip, gbAtX, gbAtY);

	// 2)
	int j = bitsPerValue - 1;

	grayScalePlanes[j] = genericRegion.getRegionBitmap();

	while (j > 0)
	{
	j--;
	genericRegion.resetBitmap();
	// 3) a)
	grayScalePlanes[j] = genericRegion.getRegionBitmap();
	// 3) b)
	grayScalePlanes = combineGrayScalePlanes(grayScalePlanes, j);
	}

	// 4)
	return computeGrayScaleValues(grayScalePlanes, bitsPerValue);
	}

	private Bitmap[] combineGrayScalePlanes(Bitmap[] grayScalePlanes, int j)
	{
	int byteIndex = 0;
	for (int y = 0; y < grayScalePlanes[j].getHeight(); y++)
	{

	for (int x = 0; x < grayScalePlanes[j].getWidth(); x += 8)
	{
	final byte newValue = grayScalePlanes[j + 1].getByte(byteIndex);
	final byte oldValue = grayScalePlanes[j].getByte(byteIndex);

	grayScalePlanes[j].setByte(byteIndex++,
	Bitmaps.combineBytes(oldValue, newValue, CombinationOperator.XOR));
	}
	}
	return grayScalePlanes;
	}

	private int[][] computeGrayScaleValues(final Bitmap[] grayScalePlanes, final int bitsPerValue)
	{
	// Gray-scale decoding procedure, page 98
	final int[][] grayScaleValues = new int[hGridHeight][hGridWidth];

	// 4)
	for (int y = 0; y < hGridHeight; y++)
	{
	for (int x = 0; x < hGridWidth; x += 8)
	{
	final int minorWidth = hGridWidth - x > 8 ? 8 : hGridWidth - x;
	int byteIndex = grayScalePlanes[0].getByteIndex(x, y);

	for (int minorX = 0; minorX < minorWidth; minorX++)
	{
	final int i = minorX + x;
	grayScaleValues[y][i] = 0;

	for (int j = 0; j < bitsPerValue; j++)
	{
	grayScaleValues[y][i] += ((grayScalePlanes[j]
	.getByte(byteIndex) >> (7 - i & 7)) & 1) * (1 << j);
	}
	}
	}
	}
	return grayScaleValues;
	}

	private int computeX(final int m, final int n)
	{
	return (hGridX + m * hRegionY + n * hRegionX) >> 8;
	}

	private int computeY(final int m, final int n)
	{
	return (hGridY + m * hRegionX - n * hRegionY) >> 8;
	}

	public void init(final SegmentHeader header, final SubInputStream sis)
	throws InvalidHeaderValueException, IOException
	{
	this.segmentHeader = header;
	this.subInputStream = sis;
	this.regionInfo = new RegionSegmentInformation(subInputStream);
	parseHeader();
	}

	public CombinationOperator getCombinationOperator()
	{
	return hCombinationOperator;
	}

	public RegionSegmentInformation getRegionInfo()
	{
	return regionInfo;
	}

	protected byte getHTemplate()
	{
	return hTemplate;
	}

	protected boolean isHSkipEnabled()
	{
	return hSkipEnabled;
	}

	protected boolean isMMREncoded()
	{
	return isMMREncoded;
	}

	protected int getHGridWidth()
	{
	return hGridWidth;
	}

	protected int getHGridHeight()
	{
	return hGridHeight;
	}

	protected int getHGridX()
	{
	return hGridX;
	}

	protected int getHGridY()
	{
	return hGridY;
	}

	protected int getHRegionX()
	{
	return hRegionX;
	}

	protected int getHRegionY()
	{
	return hRegionY;
	}

	protected byte getHDefaultPixel()
	{
	return hDefaultPixel;
	}

	// 6.6.5.1 Computing HSKIP
	private Bitmap computeHSkip(int hPatternWidth, int hPatternHeight) throws IOException
	{
	Bitmap bitmap = new Bitmap(hGridWidth, hGridHeight); // HSKIP is HGW by HGH pixels
	for (int m = 0; m < hGridHeight; ++m)
	{
	for (int n = 0; n < hGridWidth; ++n)
	{
	int x = computeX(m, n);
	int y = computeY(m, n);
	// HBW = halftoneRegionBitmap.getWidth()
	// HBH = halftoneRegionBitmap.getHeight()
	if (x + hPatternWidth <= 0 \|\| x >= halftoneRegionBitmap.getWidth() \|\| y + hPatternHeight <= 0 \|\| y >= halftoneRegionBitmap.getHeight())
	{
	bitmap.setPixel(n, m, (byte) 1);
	}
	// else no need to set 0 pixels
	}
	}
	return bitmap;
	}
	}