001/*******************************************************************************
002 * This software is provided as a supplement to the authors' textbooks on digital
003 * image processing published by Springer-Verlag in various languages and editions.
004 * Permission to use and distribute this software is granted under the BSD 2-Clause
005 * "Simplified" License (see http://opensource.org/licenses/BSD-2-Clause).
006 * Copyright (c) 2006-2023 Wilhelm Burger, Mark J. Burge. All rights reserved.
007 * Visit https://imagingbook.com for additional details.
008 ******************************************************************************/
009package imagingbook.spectral.dct;
010
011/**
012 * <p>
013 * Interface specifying all one-dimensional DCT implementations. The definition
014 * used is the one adopted by MATLAB (<a href=
015 * "https://www.mathworks.com/help/signal/ref/dct.html">https://www.mathworks.com/help/signal/ref/dct.html</a>),
016 * called "DCT-II" on Wikipedia
017 * (<a href="https://en.wikipedia.org/wiki/Discrete_cosine_transform">
018 * https://en.wikipedia.org/wiki/Discrete_cosine_transform</a>). See Ch. 20 of
019 * [1] for additional details.
020 * </p>
021 * <p>
022 * [1] W. Burger, M.J. Burge, <em>Digital Image Processing &ndash; An Algorithmic
023 * Introduction</em>, 3rd ed, Springer (2022).
024 * </p>
025 * 
026 * @see Dct1dDirect
027 * @see Dct1dFast
028 * 
029 * @author WB
030 * @version 2022/10/23
031 */
032public interface Dct1d {
033        
034        /**
035         * Returns the size of this DCT (length of data vectors).
036         * @return the size of this DCT
037         */
038        public int getSize();
039        
040        /**
041         * Sub-interface for 1D DCT implementations operating on {@code float} data.
042         */
043        public interface Float extends Dct1d {
044                
045                /**
046                 * Performs an "in-place" 1D DCT forward transformation on the supplied data.
047                 * The input signal is replaced by the associated DFT spectrum.
048                 * 
049                 * @param g the signal to be transformed (modified)
050                 */
051                void forward(float[] g);
052                
053                /**
054                 * Performs an "in-place" 1D DCT inverse transformation on the supplied spectrum.
055                 * The input spectrum is replaced by the associated signal.
056                 * 
057                 * @param G the spectrum to be transformed (modified)
058                 */
059                void inverse(float[] G);
060                
061                default void checkSize(float[] a) {
062                        if (a.length != getSize())
063                                throw new IllegalArgumentException(
064                                        String.format("wrong 1D array size %d (expected %d)", a.length, getSize()));
065                }
066                
067        }
068        
069        /**
070         * Sub-interface for 1D DCT implementations operating on {@code double} data.
071         */
072        public interface Double extends Dct1d {
073                
074                /**
075                 * Performs an "in-place" 1D DCT forward transformation on the supplied data.
076                 * The input signal is replaced by the associated DFT spectrum.
077                 * 
078                 * @param g the signal to be transformed (modified)
079                 */
080                void forward(double[] g);
081                
082                /**
083                 * Performs an "in-place" 1D DCT inverse transformation on the supplied spectrum.
084                 * The input spectrum is replaced by the associated signal.
085                 * 
086                 * @param G the spectrum to be transformed (modified)
087                 */
088                void inverse(double[] G);
089                
090                default void checkSize(double[] a) {
091                        if (a.length != getSize())
092                                throw new IllegalArgumentException(
093                                        String.format("wrong 1D array size %d (expected %d)", a.length, getSize()));
094                }
095                
096        }
097
098}