Package net.sourceforge.jiu.codecs.tiff

Source Code of net.sourceforge.jiu.codecs.tiff.TIFFDecoderLogLuv

/*
* TIFFDecoderLogLuv
*
* Copyright (c) 2002, 2003 Marco Schmidt.
* All rights reserved.
*/

package net.sourceforge.jiu.codecs.tiff;

import java.io.DataInput;
import java.io.IOException;
import net.sourceforge.jiu.codecs.tiff.TIFFConstants;
import net.sourceforge.jiu.codecs.tiff.TIFFDecoder;
import net.sourceforge.jiu.codecs.InvalidFileStructureException;
import net.sourceforge.jiu.ops.MissingParameterException;

/**
* A TIFF decoder for files compressed with the <em>LogLuv RLE</em> method.
* This compression algorithm has the value <code>34676</code>
* ({@link TIFFConstants#COMPRESSION_SGI_LOG_RLE})
* in the compression tag of an image file directory.
* Only image data with a photometric interpretation value of
* {@link TIFFConstants#PHOTOMETRIC_TRUECOLOR_LOGLUV} can be compressed with this method.
* <p>
* This implementation is based on the file <code>tif_luv.c</code> which
* is part of the TIFF library <a target="_top" href="http://www.libtiff.org">libtiff</a>.
* The original implementation was written by Greg W. Larson.
* <p>
* Learn more about the color type and its encoding on Greg's page
* <a target="_top" href="http://positron.cs.berkeley.edu/~gwlarson/pixformat/tiffluv.html">LogLuv
* Encoding for TIFF Images</a>.
* You will also find numerous sample image files there.
* @author Marco Schmidt
* @since 0.10.0
*/
public class TIFFDecoderLogLuv extends TIFFDecoder
{
  private DataInput in;
  private int compressedSize;
  private int tileWidth;
  private boolean rle;

  public void decode() throws
    InvalidFileStructureException,
    IOException
  {
    byte[] row = new byte[getBytesPerRow()];
    rle = getImageFileDirectory().getCompression() == TIFFConstants.COMPRESSION_SGI_LOG_RLE;
    for (int y = getY1(); y <= getY2(); y++)
    {
      decodeRow(row);
      putBytes(row, 0, row.length);
    }
  }

  private void decodeRow(byte[] row) throws
    InvalidFileStructureException,
    IOException
  {
    if (rle)
    {
      decodeRowRLE(row);
    }
    else
    {
      decodeRowPacked24(row);
    }
  }

  private void decodeRowPacked24(byte[] row) throws
    InvalidFileStructureException,
    IOException
  {
    int num = getImageFileDirectory().getTileWidth() * 3;
    in.readFully(row, 0, num);
  }

  private void decodeRowRLE(byte[] row) throws
    InvalidFileStructureException,
    IOException
  {
    final int BYTES_PER_PIXEL;
    if (getImageFileDirectory().getPhotometricInterpretation() == TIFFConstants.PHOTOMETRIC_LOGL)
    {
      BYTES_PER_PIXEL = 2; // LogL
    }
    else
    {
      BYTES_PER_PIXEL = 4; // LogLuv
    }
    for (int initialOffset = 0; initialOffset < BYTES_PER_PIXEL; initialOffset++)
    {
      int offset = initialOffset;
      int numPixels = tileWidth;
      do
      {
        int v1 = in.readUnsignedByte();
        if ((v1 & 128) != 0)
        {
          // run
          int runCount = v1 + (2 - 128);
          numPixels -= runCount;
          compressedSize -= 2;
          byte v2 = in.readByte();
          while (runCount-- != 0)
          {
            row[offset] = v2;
            offset += BYTES_PER_PIXEL;
          }
        }
        else
        {
          // non-run, copy data
          int runCount = v1;
          numPixels -= runCount;
          compressedSize = compressedSize - runCount - 1;
          while (runCount-- != 0)
          {
            row[offset] = in.readByte();
            offset += BYTES_PER_PIXEL;
          }
        }
        if (compressedSize < 0)
        {
          throw new InvalidFileStructureException("Ran out of compressed input bytes before completing the decoding process.");
        }
      }
      while (numPixels > 0);
    }
  }

  public Integer[] getCompressionTypes()
  {
    return new Integer[] {new Integer(TIFFConstants.COMPRESSION_SGI_LOG_RLE), new Integer(TIFFConstants.COMPRESSION_SGI_LOG_24_PACKED)};
  }

  public void initialize() throws
    IOException,
    MissingParameterException
  {
    super.initialize();
    in = getInput();
    compressedSize = getImageFileDirectory().getByteCount(getTileIndex());
    tileWidth = getImageFileDirectory().getTileWidth();
 
}
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