| /* | |
| * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved. | |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| * | |
| * This code is free software; you can redistribute it and/or modify it | |
| * under the terms of the GNU General Public License version 2 only, as | |
| * published by the Free Software Foundation. Oracle designates this | |
| * particular file as subject to the "Classpath" exception as provided | |
| * by Oracle in the LICENSE file that accompanied this code. | |
| * | |
| * This code is distributed in the hope that it will be useful, but WITHOUT | |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| * version 2 for more details (a copy is included in the LICENSE file that | |
| * accompanied this code). | |
| * | |
| * You should have received a copy of the GNU General Public License version | |
| * 2 along with this work; if not, write to the Free Software Foundation, | |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| * | |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| * or visit www.oracle.com if you need additional information or have any | |
| * questions. | |
| */ | |
| package javax.imageio.plugins.jpeg; | |
| import java.util.Arrays; | |
| /** | |
| * A class encapsulating a single JPEG quantization table. | |
| * The elements appear in natural order (as opposed to zig-zag order). | |
| * Static variables are provided for the "standard" tables taken from | |
| * Annex K of the JPEG specification, as well as the default tables | |
| * conventionally used for visually lossless encoding. | |
| * <p> | |
| * For more information about the operation of the standard JPEG plug-in, | |
| * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG | |
| * metadata format specification and usage notes</A> | |
| */ | |
| public class JPEGQTable { | |
| private static final int[] k1 = { | |
| 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, | |
| }; | |
| private static final int[] k1div2 = { | |
| 8, 6, 5, 8, 12, 20, 26, 31, | |
| 6, 6, 7, 10, 13, 29, 30, 28, | |
| 7, 7, 8, 12, 20, 29, 35, 28, | |
| 7, 9, 11, 15, 26, 44, 40, 31, | |
| 9, 11, 19, 28, 34, 55, 52, 39, | |
| 12, 18, 28, 32, 41, 52, 57, 46, | |
| 25, 32, 39, 44, 52, 61, 60, 51, | |
| 36, 46, 48, 49, 56, 50, 52, 50, | |
| }; | |
| private static final int[] k2 = { | |
| 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, | |
| }; | |
| private static final int[] k2div2 = { | |
| 9, 9, 12, 24, 50, 50, 50, 50, | |
| 9, 11, 13, 33, 50, 50, 50, 50, | |
| 12, 13, 28, 50, 50, 50, 50, 50, | |
| 24, 33, 50, 50, 50, 50, 50, 50, | |
| 50, 50, 50, 50, 50, 50, 50, 50, | |
| 50, 50, 50, 50, 50, 50, 50, 50, | |
| 50, 50, 50, 50, 50, 50, 50, 50, | |
| 50, 50, 50, 50, 50, 50, 50, 50, | |
| }; | |
| /** | |
| * The sample luminance quantization table given in the JPEG | |
| * specification, table K.1. According to the specification, | |
| * these values produce "good" quality output. | |
| * @see #K1Div2Luminance | |
| */ | |
| public static final JPEGQTable | |
| K1Luminance = new JPEGQTable(k1, false); | |
| /** | |
| * The sample luminance quantization table given in the JPEG | |
| * specification, table K.1, with all elements divided by 2. | |
| * According to the specification, these values produce "very good" | |
| * quality output. This is the table usually used for "visually lossless" | |
| * encoding, and is the default luminance table used if the default | |
| * tables and quality settings are used. | |
| * @see #K1Luminance | |
| */ | |
| public static final JPEGQTable | |
| K1Div2Luminance = new JPEGQTable(k1div2, false); | |
| /** | |
| * The sample chrominance quantization table given in the JPEG | |
| * specification, table K.2. According to the specification, | |
| * these values produce "good" quality output. | |
| * @see #K2Div2Chrominance | |
| */ | |
| public static final JPEGQTable K2Chrominance = | |
| new JPEGQTable(k2, false); | |
| /** | |
| * The sample chrominance quantization table given in the JPEG | |
| * specification, table K.1, with all elements divided by 2. | |
| * According to the specification, these values produce "very good" | |
| * quality output. This is the table usually used for "visually lossless" | |
| * encoding, and is the default chrominance table used if the default | |
| * tables and quality settings are used. | |
| * @see #K2Chrominance | |
| */ | |
| public static final JPEGQTable K2Div2Chrominance = | |
| new JPEGQTable(k2div2, false); | |
| private int[] qTable; | |
| private JPEGQTable(int[] table, boolean copy) { | |
| qTable = (copy) ? Arrays.copyOf(table, table.length) : table; | |
| } | |
| /** | |
| * Constructs a quantization table from the argument, which must | |
| * contain 64 elements in natural order (not zig-zag order). | |
| * A copy is made of the input array. | |
| * @param table the quantization table, as an {@code int} array. | |
| * @throws IllegalArgumentException if {@code table} is | |
| * {@code null} or {@code table.length} is not equal to 64. | |
| */ | |
| public JPEGQTable(int[] table) { | |
| if (table == null) { | |
| throw new IllegalArgumentException("table must not be null."); | |
| } | |
| if (table.length != 64) { | |
| throw new IllegalArgumentException("table.length != 64"); | |
| } | |
| qTable = Arrays.copyOf(table, table.length); | |
| } | |
| /** | |
| * Returns a copy of the current quantization table as an array | |
| * of {@code int}s in natural (not zig-zag) order. | |
| * @return A copy of the current quantization table. | |
| */ | |
| public int[] getTable() { | |
| return Arrays.copyOf(qTable, qTable.length); | |
| } | |
| /** | |
| * Returns a new quantization table where the values are multiplied | |
| * by {@code scaleFactor} and then clamped to the range 1..32767 | |
| * (or to 1..255 if {@code forceBaseline} is true). | |
| * <p> | |
| * Values of {@code scaleFactor} less than 1 tend to improve | |
| * the quality level of the table, and values greater than 1.0 | |
| * degrade the quality level of the table. | |
| * @param scaleFactor multiplication factor for the table. | |
| * @param forceBaseline if {@code true}, | |
| * the values will be clamped to the range 1..255 | |
| * @return a new quantization table that is a linear multiple | |
| * of the current table. | |
| */ | |
| public JPEGQTable getScaledInstance(float scaleFactor, | |
| boolean forceBaseline) { | |
| int max = (forceBaseline) ? 255 : 32767; | |
| int[] scaledTable = new int[qTable.length]; | |
| for (int i=0; i<qTable.length; i++) { | |
| int sv = (int)((qTable[i] * scaleFactor)+0.5f); | |
| if (sv < 1) { | |
| sv = 1; | |
| } | |
| if (sv > max) { | |
| sv = max; | |
| } | |
| scaledTable[i] = sv; | |
| } | |
| return new JPEGQTable(scaledTable); | |
| } | |
| /** | |
| * Returns a {@code String} representing this quantization table. | |
| * @return a {@code String} representing this quantization table. | |
| */ | |
| public String toString() { | |
| String ls = System.getProperty("line.separator", "\n"); | |
| StringBuilder sb = new StringBuilder("JPEGQTable:"+ls); | |
| for (int i=0; i < qTable.length; i++) { | |
| if (i % 8 == 0) { | |
| sb.append('\t'); | |
| } | |
| sb.append(qTable[i]); | |
| sb.append(((i % 8) == 7) ? ls : ' '); | |
| } | |
| return sb.toString(); | |
| } | |
| } |