Example #1
0
        /// <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]);
 }
Example #3
0
        /// <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);
        }