/// <summary> /// Multilevel 1-D Discreete Wavelet Transform /// </summary> /// <param name="signal">The signal. Example: new Signal(5, 6, 7, 8, 1, 2, 3, 4)</param> /// <param name="motherWavelet">The mother wavelet to be used. Example: CommonMotherWavelets.GetWaveletFromName("DB4")</param> /// <param name="level">The depth-level to perform the DWT</param> /// <param name="extensionMode">Signal extension mode</param> /// <param name="convolutionMode">Defines what convolution function should be used</param> /// <returns></returns> public static List <DecompositionLevel> ExecuteDWT(Signal signal, MotherWavelet motherWavelet, int level, SignalExtension.ExtensionMode extensionMode = SignalExtension.ExtensionMode.SymmetricHalfPoint, ConvolutionModeEnum convolutionMode = ConvolutionModeEnum.ManagedFFT) { var levels = new List <DecompositionLevel>(); var approximation = (double[])signal.Samples.Clone(); var details = (double[])signal.Samples.Clone(); var realLength = signal.Samples.Length; for (var i = 1; i <= level; i++) { var extensionSize = motherWavelet.Filters.DecompositionLowPassFilter.Length - 1; approximation = SignalExtension.Extend(approximation, extensionMode, extensionSize); details = SignalExtension.Extend(details, extensionMode, extensionSize); approximation = WaveMath.Convolve(convolutionMode, approximation, motherWavelet.Filters.DecompositionLowPassFilter); approximation = WaveMath.DownSample(approximation); details = WaveMath.Convolve(convolutionMode, details, motherWavelet.Filters.DecompositionHighPassFilter); details = WaveMath.DownSample(details); realLength = realLength / 2; levels.Add(new DecompositionLevel { Signal = signal, Index = i - 1, Approximation = approximation, Details = details }); details = (double[])approximation.Clone(); } return(levels); }
/// <summary> /// Gets the Mother Wavelet object base on it name. Returns null if the name is not found. /// </summary> /// <param name="name">The name of the wavelet. Examples: db4, haar, sym2, dmeyer, coif3</param> /// <returns></returns> public static MotherWavelet GetWaveletFromName(string name) { name = name.ToLower(); if ((name.StartsWith("d") || name.StartsWith("daub")) && Regex.Match(name, "[?d|^daub][0-9]+").Length > 0) { name = name.Replace("d", "db").Replace("dbaub", "db").Replace("dbb", "db"); } if (!MotherWaveletsCache.ContainsKey(name)) { if (!Wavelets.ContainsKey(name)) { return(null); } var wavelet = new MotherWavelet(name, (double[])Wavelets[name][1]); wavelet.CalculateFilters(); MotherWaveletsCache.Add(name, wavelet); return(wavelet); } return(MotherWaveletsCache[name]); }
/// <summary> /// Multilevel inverse discrete 1-D wavelet transform /// </summary> /// <param name="decompositionLevels">The decomposition levels of the DWT</param> /// <param name="motherWavelet">The mother wavelet to be used. Example: CommonMotherWavelets.GetWaveletFromName("DB4") </param> /// <param name="level">The depth-level to perform the DWT</param> /// <param name="convolutionMode">Defines what convolution function should be used</param> /// <returns></returns> public static double[] ExecuteIDWT(List <DecompositionLevel> decompositionLevels, MotherWavelet motherWavelet, int level = 0, ConvolutionModeEnum convolutionMode = ConvolutionModeEnum.ManagedFFT) { if (level == 0 || level > decompositionLevels.Count) { level = decompositionLevels.Count; } if (level <= 0) { return(null); } var approximation = (double[])decompositionLevels[level - 1].Approximation.Clone(); var details = (double[])decompositionLevels[level - 1].Details.Clone(); for (var i = level - 1; i >= 0; i--) { approximation = WaveMath.UpSample(approximation); approximation = WaveMath.Convolve(convolutionMode, approximation, motherWavelet.Filters.ReconstructionLowPassFilter, true, -1); details = WaveMath.UpSample(details); details = WaveMath.Convolve(convolutionMode, details, motherWavelet.Filters.ReconstructionHighPassFilter, true, -1); //sum approximation with details approximation = WaveMath.Add(approximation, details); if (i <= 0) { continue; } if (approximation.Length > decompositionLevels[i - 1].Details.Length) { approximation = SignalExtension.Deextend(approximation, decompositionLevels[i - 1].Details.Length); } details = (double[])decompositionLevels[i - 1].Details.Clone(); } return(approximation); }