Class RiceCompressor<T extends Buffer>

java.lang.Object

nom.tam.fits.compression.algorithm.rice.RiceCompressor<T>

All Implemented Interfaces:

ICompressor<T>

Direct Known Subclasses:

RiceCompressor.ByteRiceCompressor, RiceCompressor.IntRiceCompressor, RiceCompressor.ShortRiceCompressor

public abstract class RiceCompressor<T extends Buffer>
extends Object
implements ICompressor<T>

The original compression was designed by Rice, Yeh, and Miller the code was written by Richard White at STSc at the STScI and included (ported to c and adapted) in cfitsio by William Pence, NASA/GSFC. That code was then ported to java by R. van Nieuwenhoven. Later it was massively refactored to harmonize the different compression algorithms and reduce the duplicate code pieces without obscuring the algorithm itself as far as possible.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	RiceCompressor.ByteRiceCompressor
static class	RiceCompressor.DoubleRiceCompressor
static class	RiceCompressor.FloatRiceCompressor
static class	RiceCompressor.IntRiceCompressor
static class	RiceCompressor.ShortRiceCompressor

Field Summary

Fields

Modifier and Type	Field	Description
private final int	bBits
private static final int	BITS_OF_1_BYTE
private static final int	BITS_PER_BYTE
private final int	bitsPerPixel
private final int	blockSize
private static final int	BYTE_MASK
private static final int	FS_BITS_FOR_BYTE
private static final int	FS_BITS_FOR_INT
private static final int	FS_BITS_FOR_SHORT
private static final int	FS_MAX_FOR_BYTE
private static final int	FS_MAX_FOR_INT
private static final int	FS_MAX_FOR_SHORT
private final int	fsBits
private final int	fsMax
private static final Logger	LOG	logger to log to.
private static final int[]	NONZERO_COUNT
private static final long	UNSIGNED_BYTE_MASK	mask to convert a "unsigned" byte to a long.
private static final long	UNSIGNED_INTEGER_MASK	mask to convert a "unsigned" int to a long.
private static final long	UNSIGNED_SHORT_MASK	mask to convert a "unsigned" short to a long.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	RiceCompressor(RiceCompressOption option)

Method Summary

Modifier and Type	Method	Description
protected void	compress(int dataLength, int firstPixel, BitBuffer buffer)	compress the integer tiledImageOperation on a rise compressed byte buffer.
protected void	decompressBuffer(ByteBuffer readBuffer, int nx)	decompress the readbuffer and fill the pixelarray.
protected abstract int	nextPixel()
protected abstract void	nextPixel(int pixel)
private long	undoMappingAndDifferencing(long lastpix, long diff)	undo mapping and differencing Note that some of these operations will overflow the unsigned int arithmetic -- that's OK, it all works out to give the right answers in the output file.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ICompressor

compress, decompress

Field Details

UNSIGNED_BYTE_MASK

private static final long UNSIGNED_BYTE_MASK

mask to convert a "unsigned" byte to a long.

See Also:

• Constant Field Values

UNSIGNED_SHORT_MASK

private static final long UNSIGNED_SHORT_MASK

mask to convert a "unsigned" short to a long.

See Also:

• Constant Field Values

UNSIGNED_INTEGER_MASK

private static final long UNSIGNED_INTEGER_MASK

mask to convert a "unsigned" int to a long.

See Also:

• Constant Field Values

LOG

private static final Logger LOG

logger to log to.

BITS_OF_1_BYTE

private static final int BITS_OF_1_BYTE

See Also:

• Constant Field Values

BITS_PER_BYTE

private static final int BITS_PER_BYTE

See Also:

• Constant Field Values

BYTE_MASK

private static final int BYTE_MASK

See Also:

• Constant Field Values

FS_BITS_FOR_BYTE

private static final int FS_BITS_FOR_BYTE

See Also:

• Constant Field Values

FS_BITS_FOR_INT

private static final int FS_BITS_FOR_INT

See Also:

• Constant Field Values

FS_BITS_FOR_SHORT

private static final int FS_BITS_FOR_SHORT

See Also:

• Constant Field Values

FS_MAX_FOR_BYTE

private static final int FS_MAX_FOR_BYTE

See Also:

• Constant Field Values

FS_MAX_FOR_INT

private static final int FS_MAX_FOR_INT

See Also:

• Constant Field Values

FS_MAX_FOR_SHORT

private static final int FS_MAX_FOR_SHORT

See Also:

• Constant Field Values

NONZERO_COUNT

private static final int[] NONZERO_COUNT

bBits

private final int bBits

bitsPerPixel

private final int bitsPerPixel

blockSize

private final int blockSize

fsBits

private final int fsBits

fsMax

private final int fsMax

Constructor Details

RiceCompressor

private RiceCompressor(RiceCompressOption option)

Method Details

undoMappingAndDifferencing

private long undoMappingAndDifferencing(long lastpix,
 long diff)

undo mapping and differencing Note that some of these operations will overflow the unsigned int arithmetic -- that's OK, it all works out to give the right answers in the output file.

In java this is more complicated because of the missing unsigned integers. trying to simulate the behavior

Parameters:

lastpix - the current last pix value

diff - the difference to "add"

Returns:

return the new lastpiy value

compress

protected void compress(int dataLength,
 int firstPixel,
 BitBuffer buffer)

compress the integer tiledImageOperation on a rise compressed byte buffer.

Parameters:

dataLength - length of the data to compress

firstPixel - the value of the first pixel

buffer - the buffer to write to

decompressBuffer

protected void decompressBuffer(ByteBuffer readBuffer,
 int nx)

decompress the readbuffer and fill the pixelarray.

Parameters:

readBuffer - input buffer

nx - the number of pixel to uncompress

nextPixel

protected abstract int nextPixel()

nextPixel

protected abstract void nextPixel(int pixel)