Class Dct
- java.lang.Object
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- org.apache.commons.imaging.formats.jpeg.decoder.Dct
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final class Dct extends java.lang.Object
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Field Summary
Fields Modifier and Type Field Description private static float
A1
private static float
A2
private static float
A3
private static float
A4
private static float
A5
private static float
C2
private static float
C4
private static float
C6
private static float[]
DCT_SCALING_FACTORS
private static float[]
IDCT_SCALING_FACTORS
private static float
Q
private static float
R
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Constructor Summary
Constructors Modifier Constructor Description private
Dct()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static void
forwardDCT8(float[] vector)
Fast forward Dct using AA&N.static void
forwardDCT8x8(float[] matrix)
static void
inverseDCT8(float[] vector)
Fast inverse Dct using AA&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)
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Field Detail
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DCT_SCALING_FACTORS
private static final float[] DCT_SCALING_FACTORS
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IDCT_SCALING_FACTORS
private static final float[] IDCT_SCALING_FACTORS
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A1
private static final float A1
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A2
private static final float A2
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A3
private static final float A3
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A4
private static final float A4
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A5
private static final float A5
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C2
private static final float C2
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C4
private static final float C4
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C6
private static final float C6
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Q
private static final float Q
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R
private static final float R
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Method Detail
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scaleQuantizationVector
public static void scaleQuantizationVector(float[] vector)
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scaleDequantizationVector
public static void scaleDequantizationVector(float[] vector)
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scaleQuantizationMatrix
public static void scaleQuantizationMatrix(float[] matrix)
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scaleDequantizationMatrix
public static void scaleDequantizationMatrix(float[] matrix)
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forwardDCT8
public static void forwardDCT8(float[] vector)
Fast forward Dct using AA&N. Taken from the book "JPEG still image data compression standard", by Pennebaker and Mitchell, chapter 4, figure "4-8".
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forwardDCT8x8
public static void forwardDCT8x8(float[] matrix)
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inverseDCT8
public static void inverseDCT8(float[] vector)
Fast inverse Dct using AA&N. This is taken from the beautiful 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.
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inverseDCT8x8
public static void inverseDCT8x8(float[] matrix)
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