1: /// <summary>

   2: /// Does thermal erosion on the image

   3: /// </summary>

   4: /// <param name="OriginalImage">Image to manipulate</param>

   5: /// <param name="T">Threshold value</param>

   6: /// <param name="C">Change value</param>

   7: /// <param name="Iterations">Number of iterations</param>

   8: /// <returns>A bitmap image</returns>

   9: public static Bitmap ThermalErosion(Bitmap OriginalImage,float T,float C,int Iterations)

  10: {

  11:     Bitmap BlackAndWhiteImage = Image.ConvertBlackAndWhite(OriginalImage);

  12:     BitmapData BlackAndWhiteData = Image.LockImage(BlackAndWhiteImage);

  13:     int BlackAndWhitePixelSize = Image.GetPixelSize(BlackAndWhiteData);

  14:     float[] HeightDifferences = new float[8];

  15:     for (int i = 0; i < Iterations; ++i)

  16:     {

  17:         for (int x = 0; x < BlackAndWhiteImage.Width; ++x)

  18:         {

  19:             for (int y = 0; y < BlackAndWhiteImage.Height; ++y)

  20:             {

  21:                 int X1 = x - 1;

  22:                 int Y1 = y - 1;

  23:                 X1=Math.MathHelper.Clamp(X1, BlackAndWhiteImage.Width-1, 0);

  24:                 Y1=Math.MathHelper.Clamp(Y1, BlackAndWhiteImage.Height-1, 0);

  25:                 int X2 = x + 1;

  26:                 int Y2 = y + 1;

  27:                 X2=Math.MathHelper.Clamp(X2, BlackAndWhiteImage.Width-1, 0);

  28:                 Y2=Math.MathHelper.Clamp(Y2, BlackAndWhiteImage.Height-1, 0);

  29:                 HeightDifferences[0] = GetHeightDifferences(x, y, X1, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  30:                 HeightDifferences[1] = GetHeightDifferences(x, y, x, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  31:                 HeightDifferences[2] = GetHeightDifferences(x, y, X2, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  32:                 HeightDifferences[3] = GetHeightDifferences(x, y, X1, y, BlackAndWhiteData, BlackAndWhitePixelSize);

  33:                 HeightDifferences[4] = GetHeightDifferences(x, y, X2, y, BlackAndWhiteData, BlackAndWhitePixelSize);

  34:                 HeightDifferences[5] = GetHeightDifferences(x, y, X1, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

  35:                 HeightDifferences[6] = GetHeightDifferences(x, y, x, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

  36:                 HeightDifferences[7] = GetHeightDifferences(x, y, X2, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

  37:                 float MaxDifference = 0.0f;

  38:                 float DifferenceTotal = 0.0f;

  39:                 float NumberOver = 0;

  40:                 for (int z = 0; z < 8; ++z)

  41:                 {

  42:                     if (HeightDifferences[z] > MaxDifference)

  43:                     {

  44:                         MaxDifference = HeightDifferences[z];

  45:                     }

  46:                     if (HeightDifferences[z] > T)

  47:                     {

  48:                         DifferenceTotal += HeightDifferences[z];

  49:                         ++NumberOver;

  50:                     }

  51:                 }

  52:                 float Height = GetHeight(x, y, BlackAndWhiteData, BlackAndWhitePixelSize);

  53:                 if (X1 != x && Y1 != y && HeightDifferences[0] != 0.0f && DifferenceTotal != 0.0f)

  54:                 {

  55:                     Height = GetHeight(X1, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  56:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[0] / DifferenceTotal);

  57:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  58:                     SetHeight(X1, Y1, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  59:                 }

  60:                 if (Y1 != y && HeightDifferences[1] != 0.0f && DifferenceTotal != 0.0f)

  61:                 {

  62:                     Height = GetHeight(x, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  63:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[1] / DifferenceTotal);

  64:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  65:                     SetHeight(x, Y1, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  66:                 }

  67:                 if (X2 != x && Y1 != y && HeightDifferences[2] != 0.0f && DifferenceTotal != 0.0f)

  68:                 {

  69:                     Height = GetHeight(X2, Y1, BlackAndWhiteData, BlackAndWhitePixelSize);

  70:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[2] / DifferenceTotal);

  71:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  72:                     SetHeight(X2, Y1, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  73:                 }

  74:                 if (X1 != x && HeightDifferences[3] != 0.0f && DifferenceTotal != 0.0f)

  75:                 {

  76:                     Height = GetHeight(X1, y, BlackAndWhiteData, BlackAndWhitePixelSize);

  77:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[3] / DifferenceTotal);

  78:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  79:                     SetHeight(X1, y, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  80:                 }

  81:                 if (X2 != x && HeightDifferences[4] != 0.0f && DifferenceTotal != 0.0f)

  82:                 {

  83:                     Height = GetHeight(X2, y, BlackAndWhiteData, BlackAndWhitePixelSize);

  84:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[4] / DifferenceTotal);

  85:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  86:                     SetHeight(X2, y, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  87:                 }

  88:                 if (X1 != x && Y2 != y && HeightDifferences[5] != 0.0f && DifferenceTotal != 0.0f)

  89:                 {

  90:                     Height = GetHeight(X1, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

  91:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[5] / DifferenceTotal);

  92:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

  93:                     SetHeight(X1, Y2, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

  94:                 }

  95:                 if (Y2 != y && HeightDifferences[6] != 0.0f && DifferenceTotal != 0.0f)

  96:                 {

  97:                     Height = GetHeight(x, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

  98:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[6] / DifferenceTotal);

  99:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

 100:                     SetHeight(x, Y2, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

 101:                 }

 102:                 if (X2 != x && Y2 != y && HeightDifferences[7] != 0.0f && DifferenceTotal != 0.0f)

 103:                 {

 104:                     Height = GetHeight(X2, Y2, BlackAndWhiteData, BlackAndWhitePixelSize);

 105:                     Height = Height + C * (MaxDifference - T) * (HeightDifferences[7] / DifferenceTotal);

 106:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

 107:                     SetHeight(X2, Y2, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

 108:                 }

 109:                 if (DifferenceTotal != 0.0f)

 110:                 {

 111:                     Height = GetHeight(x, y, BlackAndWhiteData, BlackAndWhitePixelSize);

 112:                     Height = Height + (MaxDifference - (NumberOver * MaxDifference * T / DifferenceTotal));

 113:                     Height = Math.MathHelper.Clamp(Height, 1.0f, -1.0f);

 114:                     SetHeight(x, y, Height, BlackAndWhiteData, BlackAndWhitePixelSize);

 115:                 }

 116:             }

 117:         }

 118:     }

 119:     Image.UnlockImage(BlackAndWhiteImage, BlackAndWhiteData);

 120:     return BlackAndWhiteImage;

 121: }

 122:  

 123: private static float GetHeightDifferences(int x, int y, int X1, int Y1, BitmapData BlackAndWhiteData, int BlackAndWhitePixelSize)

 124: {

 125:     Color TempColor = Image.GetPixel(BlackAndWhiteData, x, y, BlackAndWhitePixelSize);

 126:     float Height = GetHeight(TempColor);

 127:     TempColor = Image.GetPixel(BlackAndWhiteData, X1, Y1, BlackAndWhitePixelSize);

 128:     float Height2 = GetHeight(TempColor);

 129:     return Height - Height2;

 130: }

 131:  

 132: private static void SetHeight(int x, int y, float Value,BitmapData Data,int PixelSize)

 133: {

 134:     Value *= 0.5f;

 135:     Value += 0.5f;

 136:     int Value2 = (int)(Value * 255.0f);

 137:     Color TempColor = Color.FromArgb(Value2, Value2, Value2);

 138:     Image.SetPixel(Data, x, y, TempColor, PixelSize);

 139: }

 140:  

 141: private static float GetHeight(int x, int y, BitmapData BlackAndWhiteData, int BlackAndWhitePixelSize)

 142: {

 143:     Color TempColor = Image.GetPixel(BlackAndWhiteData, x, y, BlackAndWhitePixelSize);

 144:     return GetHeight(TempColor);

 145: }

 146:  

 147: private static float GetHeight(Color Color)

 148: {

 149:     return (float)Color.R / 255.0f;

 150: }