TurboWavelets/HaarWavelet2D.cs

// 
// HaarWavelet2D.cs
//  
// Author:
//       Stefan Moebius
// Date:
//       2016-04-24
// 
// Copyright (c) 2016 Stefan Moebius
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

namespace TurboWavelets
{
    public class HaarWavelet2D : Wavelet2D
    {
        protected const int   AllowedMinSize    = 2;
        protected const float Scale             = 2.0f;
        protected const float InvScale          = 0.5f;
        protected const float Mean              = 0.5f;
        protected const float InvMean           = 2.0f;

        public HaarWavelet2D (int width, int height)
            : base(AllowedMinSize, AllowedMinSize, width, height)
        {   
        }

        public HaarWavelet2D (int width, int height, int minSize)
            : base(minSize, AllowedMinSize, width, height)
        {
        }

        #pragma warning disable 1591 // do not show compiler warnings of the missing descriptions
        override protected void TransformRow (float[,] src, float[,] dst, int y, int length)
        {
            if (length >= AllowedMinSize) {
                int half = length >> 1;
                int offSrc = 0;
                // number of low-pass values
                int numLFValues = half + (length & 1);

                for (int i = 0; i < half; i++) {
                    float a = src [offSrc    , y];
                    float b = src [offSrc + 1, y];
                    //calculate the mean of a and b and scale with factor 2
                    //So no multiplication needed at all
                    dst [i              , y] = (a + b);
                    dst [i + numLFValues, y] = (b - a) * Mean;
                    offSrc += 2;
                }                           
                if ((length & 1) != 0) {
                    dst [numLFValues - 1, y] = src [length - 1, y] * Scale;
                }       
            } else {
                for (int i = 0; i < length; i++)
                    dst [i, y] = src [i, y];
            }
        }

        override protected void TransformCol (float[,] src, float[,] dst, int x, int length)
        {
            if (length >= AllowedMinSize) {
                int half = length >> 1;
                int offSrc = 0;
                // number of low-pass values
                int numLFValues = half + (length & 1);

                for (int i = 0; i < half; i++) {
                    float a = src [x, offSrc    ];
                    float b = src [x, offSrc + 1];
                    //calculate the mean of a and b and scale with factor 2
                    //So no multiplication needed at all
                    dst [x, i              ] = (a + b);
                    dst [x, i + numLFValues] = (b - a) * Mean;
                    offSrc += 2;
                }                           
                if ((length & 1) != 0) {
                    dst [x, numLFValues - 1] = src [x, length - 1] * Scale;
                }   
            } else {
                for (int i = 0; i < length; i++)
                    dst [x, i] = src [x, i];
            }
        }

        override protected void InvTransformRow (float[,] src, float[,] dst, int y, int length)
        {
            if (length >= AllowedMinSize) {
                int half = length >> 1;
                int offDst = 0;
                // number of low-pass values
                int numLFValues = half + (length & 1);

                for (int i = 0; i < half; i++) {
                    float a = src [i, y              ] * InvScale;
                    float b = src [i + numLFValues, y];
                    dst [offDst,     y] = a - b;
                    dst [offDst + 1, y] = a + b;
                    offDst += 2;
                }                           
                if ((length & 1) != 0) {
                    dst [length - 1, y] = src [numLFValues - 1, y] * InvScale; 
                }
            } else {
                for (int i = 0; i < length; i++)
                    dst [i, y] = src [i, y];
            }
        }

        override protected void InvTransformCol (float[,] src, float[,] dst, int x, int length)
        {
            if (length >= AllowedMinSize) {
                int half = length >> 1;
                int offDst = 0;
                // number of low-pass values
                int numLFValues = half + (length & 1);

                for (int i = 0; i < half; i++) {
                    float a = src [x, i              ] * InvScale;
                    float b = src [x, i + numLFValues];
                    dst [x,     offDst] = a - b;
                    dst [x, offDst + 1] = a + b;
                    offDst += 2;
                }                           
                if ((length & 1) != 0) {
                    dst [x, length - 1] = src [x, numLFValues - 1] * InvScale;
                } 
            } else {
                for (int i = 0; i < length; i++)
                    dst [x, i] = src [x, i];
            }
        }
        #pragma warning restore 1591
    }
}