/*
*
* Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/**********************************************************************
**********************************************************************
**********************************************************************
*** COPYRIGHT (c) 1997-1998 Eastman Kodak Company. ***
*** As an unpublished work pursuant to Title 17 of the United ***
*** States Code. All rights reserved. ***
**********************************************************************
**********************************************************************
**********************************************************************/
package com.sun.image.codec.jpeg;
/** Class to encapsulate the JPEG quantization tables.
* <p>
* Note that the classes in the com.sun.image.codec.jpeg package are not
* part of the core Java APIs. They are a part of Sun's JDK and JRE
* distributions. Although other licensees may choose to distribute these
* classes, developers cannot depend on their availability in non-Sun
* implementations. We expect that equivalent functionality will eventually
* be available in a core API or standard extension.
* <p>
*/
public class JPEGQTable {
/** Quantization step for each coefficient in zig-zag order */
private int quantval[];
/** The number of coefficients in a DCT block */
private static final byte QTABLESIZE = 64;
/**
* This is the sample luminance quantization table given in the
* JPEG spec section K.1, expressed in zigzag order. The spec says
* that the values given produce "good" quality, and when divided
* by 2, "very good" quality.
*/
public static final JPEGQTable StdLuminance = new JPEGQTable();
static {
int [] lumVals = {
16, 11, 12, 14, 12, 10, 16, 14,
13, 14, 18, 17, 16, 19, 24, 40,
26, 24, 22, 22, 24, 49, 35, 37,
29, 40, 58, 51, 61, 60, 57, 51,
56, 55, 64, 72, 92, 78, 64, 68,
87, 69, 55, 56, 80, 109, 81, 87,
95, 98, 103, 104, 103, 62, 77, 113,
121, 112, 100, 120, 92, 101, 103, 99
};
StdLuminance.quantval = lumVals;
}
/**
* This is the sample luminance quantization table given in the
* JPEG spec section K.1, expressed in zigzag order. The spec says
* that the values given produce "good" quality, and when divided
* by 2, "very good" quality.
*/
public static final JPEGQTable StdChrominance = new JPEGQTable();
static {
int [] chromVals = {
17, 18, 18, 24, 21, 24, 47, 26,
26, 47, 99, 66, 56, 66, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99
};
StdChrominance.quantval = chromVals;
}
/**
* Constructs an empty quantization table. This is used to create
* the Std Q-Tables.
*/
private JPEGQTable() {
quantval = new int[QTABLESIZE];
}
/**
* Constructs an quantization table from the array that was
* passed. The coefficents must be in zig-zag order. The array
* must be of length 64.
* @param table the quantization table (this is copied).
*/
public JPEGQTable( int table[] ) {
if ( table.length != QTABLESIZE ) {
throw new IllegalArgumentException
("Quantization table is the wrong size.");
} else {
quantval = new int[QTABLESIZE];
System.arraycopy( table, 0, quantval, 0, QTABLESIZE );
}
}
/**
* Returns the current quantization table as an array of ints in
* zig zag order.
* @return A copy of the contained quantization table.
*/
public int[] getTable() {
int[] table = new int[QTABLESIZE];
System.arraycopy( quantval, 0, table, 0, QTABLESIZE );
return table;
}
/**
* Returns a new Quantization table where the values are
* multiplied by scaleFactor and then clamped to the range
* 1..32767 (or to 1..255 if forceBaseline is 'true'). <P>
* Values less than one tend to improve the quality level of the
* table, and values greater than one degrade the quality level of
* the table.
* @param scaleFactor the multiplication factor for the table
* @param forceBaseline if true the values will be clamped
* to the range [1 .. 255]
* @return A new Q-Table that is a linear multiple of this Q-Table
*/
public JPEGQTable getScaledInstance(float scaleFactor,
boolean forceBaseline ) {
long max = (forceBaseline)?255L:32767L;
int []ret = new int[QTABLESIZE];
for (int i=0; i<QTABLESIZE; i++ ) {
long holder = (long)((quantval[i] * scaleFactor) + 0.5);
// limit to valid range
if (holder <= 0L) holder = 1L;
// Max quantizer for 12 bits
if (holder > max ) holder = max;
ret[i] = (int)holder;
}
return new JPEGQTable(ret);
}
}