1: /// <summary>

   2: /// Adjusts the Contrast

   3: /// </summary>

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

   5: /// <param name="Value">Used to set the contrast (-100 to 100)</param>

   6: /// <returns>A bitmap object</returns>

   7: public static Bitmap AdjustContrast(Bitmap OriginalImage, float Value)

   8: {

   9:     Bitmap NewBitmap = new Bitmap(OriginalImage.Width, OriginalImage.Height);

  10:     BitmapData NewData = Image.LockImage(NewBitmap);

  11:     BitmapData OldData = Image.LockImage(OriginalImage);

  12:     int NewPixelSize = Image.GetPixelSize(NewData);

  13:     int OldPixelSize = Image.GetPixelSize(OldData);

  14:     Value = (100.0f + Value) / 100.0f;

  15:     Value *= Value;

  16:  

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

  18:     {

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

  20:         {

  21:             Color Pixel = Image.GetPixel(OldData, x, y, OldPixelSize);

  22:             float Red = Pixel.R / 255.0f;

  23:             float Green = Pixel.G / 255.0f;

  24:             float Blue = Pixel.B / 255.0f;

  25:             Red = (((Red - 0.5f) * Value) + 0.5f) * 255.0f;

  26:             Green = (((Green - 0.5f) * Value) + 0.5f) * 255.0f;

  27:             Blue = (((Blue - 0.5f) * Value) + 0.5f) * 255.0f;

  28:             Image.SetPixel(NewData, x, y,

  29:                 Color.FromArgb(MathHelper.Clamp((int)Red, 255, 0),

  30:                 MathHelper.Clamp((int)Green, 255, 0),

  31:                 MathHelper.Clamp((int)Blue, 255, 0)),

  32:                 NewPixelSize);

  33:         }

  34:     }

  35:     Image.UnlockImage(NewBitmap, NewData);

  36:     Image.UnlockImage(OriginalImage, OldData);

  37:     return NewBitmap;

  38: }