| /* |
| * 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 the input array. |
| * @param table the quantization table, as an <code>int</code> array. |
| * @throws IllegalArgumentException if <code>table</code> is |
| * <code>null</code> or <code>table.length</code> 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</code> and then clamped to the range 1..32767 |
| * (or to 1..255 if <code>forceBaseline</code> is true). |
| * <p> |
| * Values of <code>scaleFactor</code> 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</code>, |
| * 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(); |
| } |
| } |
