replicant-frameworks_native/awt/javax/imageio/plugins/jpeg/JPEGQTable.java
The Android Open Source Project 7c1b96a165 Initial Contribution
2008-10-21 07:00:00 -07:00

163 lines
5.3 KiB
Java

/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Rustem V. Rafikov
* @version $Revision: 1.3 $
*/
package javax.imageio.plugins.jpeg;
/**
* The JPEGQTable class represents a single JPEG quantization table
* and provides for the standard tables taken from the JPEG specification.
*/
public class JPEGQTable {
/** The Constant SIZE. */
private final static int SIZE = 64;
/** The Constant BASELINE_MAX. */
private final static int BASELINE_MAX = 255;
/** The Constant MAX. */
private final static int MAX = 32767;
/** The table. */
private int[] theTable;
/*
* K1 & K2 tables can be found in the JPEG format specification
* at http://www.w3.org/Graphics/JPEG/itu-t81.pdf
*/
/** The Constant K1LumTable. */
private static final int[] K1LumTable = new int[] {
16, 11, 10, 16, 24, 40, 51, 61,
12, 12, 14, 19, 26, 58, 60, 55,
14, 13, 16, 24, 40, 57, 69, 56,
14, 17, 22, 29, 51, 87, 80, 62,
18, 22, 37, 56, 68, 109, 103, 77,
24, 35, 55, 64, 81, 104, 113, 92,
49, 64, 78, 87, 103, 121, 120, 101,
72, 92, 95, 98, 112, 100, 103, 99
};
/** The Constant K2ChrTable. */
private static final int[] K2ChrTable = new int[] {
17, 18, 24, 47, 99, 99, 99, 99,
18, 21, 26, 66, 99, 99, 99, 99,
24, 26, 56, 99, 99, 99, 99, 99,
47, 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
};
/**
* The K1Luminance indicates standart table K.1 from JPEG
* specification and produces "good" quality output.
*/
public static final JPEGQTable K1Luminance = new JPEGQTable(K1LumTable);
/**
* The K1Div2Luminance indicates K.1 table from JPEG
* specification with all elements divided by 2 and produces
* "very good" quality output.
*/
public static final JPEGQTable K1Div2Luminance = K1Luminance.getScaledInstance(0.5f, true);
/**
* The K2Chrominance indicates K.2 table from JPEG
* specification and produces "good" quality output.
*/
public static final JPEGQTable K2Chrominance = new JPEGQTable(K2ChrTable);
/**
* The Constant K2Div2Chrominance indicates K.2 table from JPEG
* specification with all elements divided by 2 and produces
* "very good" quality output.
*/
public static final JPEGQTable K2Div2Chrominance = K2Chrominance.getScaledInstance(0.5f, true);;
/**
* Instantiates a new JPEGQTable from the array, which
* should contain 64 elements in natural order.
*
* @param table the quantization table.
*/
public JPEGQTable(int[] table) {
if (table == null) {
throw new IllegalArgumentException("table should not be NULL");
}
if (table.length != SIZE) {
throw new IllegalArgumentException("illegal table size: " + table.length);
}
theTable = table.clone();
}
/**
* Gets the current quantization table as an array of int values.
*
* @return the current quantization table as an array of int values.
*/
public int[] getTable() {
return theTable.clone();
}
/**
* Gets the scaled instance as quantization table where
* the values are multiplied by the scaleFactor and then clamped
* if forceBaseline is true.
*
* @param scaleFactor the scale factor of table.
* @param forceBaseline the force baseline flag, the values
* should be clamped if true.
*
* @return the new quantization table.
*/
public JPEGQTable getScaledInstance(float scaleFactor, boolean forceBaseline) {
int table[] = new int[SIZE];
int maxValue = forceBaseline ? BASELINE_MAX : MAX;
for (int i = 0; i < theTable.length; i++) {
int rounded = Math.round(theTable[i] * scaleFactor);
if (rounded < 1) {
rounded = 1;
}
if (rounded > maxValue) {
rounded = maxValue;
}
table[i] = rounded;
}
return new JPEGQTable(table);
}
/**
* Returns the string representation of this JPEGQTable object.
*
* @return the string representation of this JPEGQTable object.
*/
@Override
public String toString() {
//-- TODO more informative info
return "JPEGQTable";
}
}