图片帮助类

public class ImageUtil
  {
    /// <summary>
    /// 检查RGB值ed有效范围
    /// </summary>
    /// <param name="rgb"></param>
    /// <returns></returns>
    private static int verifyRGB(int rgb)
    {
      if (rgb < 0)
        return 0;
      if (rgb > 255)
        return 255;
      return rgb;
    }

    /// <summary>
    /// 反色处理
    /// </summary>
    /// <param name="bmp"></param>
    public static Bitmap FilterInverse(Bitmap bmp)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color pixel;

      for (int x = 0; x < bmp.Width; x++)
      {
        for (int y = 0; y < bmp.Height; y++)
        {
          pixel = bmp.GetPixel(x, y);
          result.SetPixel(x, y, Color.FromArgb(255 - pixel.R, 255 - pixel.G, 255 - pixel.B));
        }
      }
      return result;
    }

    /// <summary>
    /// 浮雕处理
    /// </summary>
    /// <param name="bmp"></param>
    public static Bitmap FilterEmbossment(Bitmap bmp)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color color1, color2;
      int r = 0, g = 0, b = 0;

      for (int x = 0; x < bmp.Width - 1; x++)
      {
        for (int y = 0; y < bmp.Height - 1; y++)
        {
          color1 = bmp.GetPixel(x, y);
          color2 = bmp.GetPixel(x + 1, y + 1);
          r = Math.Abs(color1.R - color2.R + 128);
          g = Math.Abs(color1.G - color2.G + 128);
          b = Math.Abs(color1.B - color2.B + 128);

          result.SetPixel(x, y, Color.FromArgb(verifyRGB(r), verifyRGB(g), verifyRGB(b)));
        }
      }
      return result;
    }

    /// <summary>
    /// 滤色处理
    /// </summary>
    /// <param name="bmp"></param>
    public static Bitmap FilterColour(Bitmap bmp)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color pixel;

      for (int x = 0; x < bmp.Width; x++)
      {
        for (int y = 0; y < bmp.Height; y++)
        {
          pixel = bmp.GetPixel(x, y);
          result.SetPixel(x, y, Color.FromArgb(0, pixel.G, pixel.B));
        }
      }
      return result;
    }

    /// <summary>
    /// 黑白处理
    /// </summary>
    /// <param name="bmp"></param>
    public static Bitmap FilterBlackWhite(Bitmap bmp)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color pixel;
      int val;

      for (int x = 0; x < bmp.Width; x++)
      {
        for (int y = 0; y < bmp.Height; y++)
        {
          pixel = bmp.GetPixel(x, y);
          val = (pixel.R + pixel.G + pixel.B) / 3;
          result.SetPixel(x, y, Color.FromArgb(val, val, val));
        }
      }
      return result;
    }

    /// <summary>
    /// 亮度处理
    /// </summary>
    /// <param name="bmp"></param>
    /// <param name="val">增加或减少亮度(-255至255)</param>
    public static Bitmap FilterLightness(Bitmap bmp, int val)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color pixel;

      for (int x = 0; x < bmp.Width; x++)
      {
        for (int y = 0; y < bmp.Height; y++)
        {
          pixel = bmp.GetPixel(x, y);
          result.SetPixel(x, y, Color.FromArgb(verifyRGB(pixel.R + val), verifyRGB(pixel.G + val), verifyRGB(pixel.B + val)));
        }
      }
      return result;
    }

    /// <summary>
    /// 透明度处理
    /// </summary>
    /// <param name="bmp"></param>
    /// <param name="val">透明度（0-255）</param>
    public static Bitmap FilterTransparent(Bitmap bmp, int val)
    {
      Bitmap result = new Bitmap(bmp.Width, bmp.Height);
      Color pixel;

      for (int x = 0; x < bmp.Width; x++)
      {
        for (int y = 0; y < bmp.Height; y++)
        {
          pixel = bmp.GetPixel(x, y);
          result.SetPixel(x, y, Color.FromArgb(val, pixel.R, pixel.G, pixel.B));
        }
      }
      return result;
    }

  }