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/*
* 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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