Package nom.tam.fits.compression.algorithm.hcompress

Class HCompress

java.lang.Object

nom.tam.fits.compression.algorithm.hcompress.HCompress

public class HCompress
extends Object

(for internal use) A hierarchical data compression algoritm, used by the Hubble Data Archive and the STScI Digital Sky Survey.

The original compression code was written by Richard White 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. The original site for the algorithm is

See http://www.stsci.edu /software/hcompress.html

Author:

Richard White, William Pence, Richard van Nieuwenhoven

See Also:

• HDecompress
• HCompressorOption

Field Summary

Fields

Modifier and Type	Field	Description
protected static final int	BITS_OF_1_BYTE
protected static final int	BITS_OF_1_NYBBLE
protected static final int	BYTE_MASK
protected static final int	NYBBLE_MASK
protected static final double	ROUNDING_HALF

Constructor Summary

Constructors

Constructor	Description
HCompress()

Method Summary

Modifier and Type	Method	Description
protected void	compress(long[] aa, int ny, int nx, int scale, ByteBuffer output)

Methods inherited from class java.lang.Object

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

Field Details

ROUNDING_HALF

protected static final double ROUNDING_HALF

See Also:

• Constant Field Values

BITS_OF_1_BYTE

protected static final int BITS_OF_1_BYTE

See Also:

• Constant Field Values

BITS_OF_1_NYBBLE

protected static final int BITS_OF_1_NYBBLE

See Also:

• Constant Field Values

BYTE_MASK

protected static final int BYTE_MASK

See Also:

• Constant Field Values

NYBBLE_MASK

protected static final int NYBBLE_MASK

See Also:

• Constant Field Values

Constructor Details

HCompress

public HCompress()

Method Details

compress

protected void compress(long[] aa,
 int ny,
 int nx,
 int scale,
 ByteBuffer output)