Class Dct

java.lang.Object

org.apache.commons.imaging.formats.jpeg.decoder.Dct

final class Dct
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
private static final float	A1
private static final float	A2
private static final float	A3
private static final float	A4
private static final float	A5
private static final float	C2
private static final float	C4
private static final float	C6
private static final float[]	DCT_SCALING_FACTORS
private static final float[]	IDCT_SCALING_FACTORS
private static final float	Q
private static final float	R

Constructor Summary

Constructors

Modifier	Constructor	Description
private	Dct()

Method Summary

Modifier and Type	Method	Description
static void	forwardDct8(float[] vector)	Fast forward Dct using AAinvalid input: '&N'.
static void	forwardDct8x8(float[] matrix)
static void	inverseDct8(float[] vector)	Fast inverse Dct using AAinvalid input: '&N'.
static void	inverseDct8x8(float[] matrix)
static void	scaleDequantizationMatrix(float[] matrix)
static void	scaleDequantizationVector(float[] vector)
static void	scaleQuantizationMatrix(float[] matrix)
static void	scaleQuantizationVector(float[] vector)

Methods inherited from class Object

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

Field Details

DCT_SCALING_FACTORS

private static final float[] DCT_SCALING_FACTORS

IDCT_SCALING_FACTORS

private static final float[] IDCT_SCALING_FACTORS

A1

private static final float A1

A2

private static final float A2

A3

private static final float A3

A4

private static final float A4

A5

private static final float A5

C2

private static final float C2

C4

private static final float C4

C6

private static final float C6

Q

private static final float Q

R

private static final float R

Constructor Details

Dct

private Dct()

Method Details

forwardDct8

public static void forwardDct8(float[] vector)

Fast forward Dct using AAinvalid input: '&N'. Taken from the book "JPEG still image data compression standard", by Pennebaker and Mitchell, chapter 4, figure "4-8".

Parameters:

vector - vector.

forwardDct8x8

public static void forwardDct8x8(float[] matrix)

inverseDct8

public static void inverseDct8(float[] vector)

Fast inverse Dct using AAinvalid input: '&N'. This is taken from the beautiful [BROEKN URL] http://vsr.finermatik.tu-chemnitz.de/~jan/MPEG/HTML/IDCT.html which gives easy equations and properly explains constants and scaling factors. Terms have been inlined and the negation optimized out of existence.

Parameters:

vector - vector.

inverseDct8x8

public static void inverseDct8x8(float[] matrix)

scaleDequantizationMatrix

public static void scaleDequantizationMatrix(float[] matrix)

scaleDequantizationVector

public static void scaleDequantizationVector(float[] vector)

scaleQuantizationMatrix

public static void scaleQuantizationMatrix(float[] matrix)

scaleQuantizationVector

public static void scaleQuantizationVector(float[] vector)