灰度处理

将彩色的图片转换成黑白有很多种方法：

1。红色转换灰度

  Bitmap desc = new Bitmap(source.Width, source.Height);

BitmapData sourcedata = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), 
                ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
BitmapData descdata = desc.LockBits(new Rectangle(0, 0, desc.Width, desc.Height),
                ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

unsafe
{
      byte* sourceptr = (byte*)sourcedata.Scan0;  //B,G,R
      sourceptr += 2;
      byte* descptr = (byte*)descdata.Scan0;
      for (int x = 0; x < source.Height; x++)
      {
           for (int y = 0; y < source.Width; y++)
           {
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                sourceptr += 3;
            }
            sourceptr += sourcedata.Stride - source.Width * 3;
            descptr += descdata.Stride - desc.Width * 3;
       }
}
source.UnlockBits(sourcedata);
desc.UnlockBits(descdata);

2。绿色转换灰度

Bitmap desc = new Bitmap(source.Width, source.Height);
BitmapData sourcedata = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), 
                ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
BitmapData descdata = desc.LockBits(new Rectangle(0, 0, desc.Width, desc.Height),
                ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

unsafe
{
      byte* sourceptr = (byte*)sourcedata.Scan0;  //B,G,R
      sourceptr += 1;
      byte* descptr = (byte*)descdata.Scan0;
      for (int x = 0; x < source.Height; x++)
      {
           for (int y = 0; y < source.Width; y++)
           {
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                sourceptr += 3;
            }
            sourceptr += sourcedata.Stride - source.Width * 3;
            descptr += descdata.Stride - desc.Width * 3;
       }
}
source.UnlockBits(sourcedata);
desc.UnlockBits(descdata);

3。蓝色转换灰度

 Bitmap desc = new Bitmap(source.Width, source.Height);

BitmapData sourcedata = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), 
                ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
BitmapData descdata = desc.LockBits(new Rectangle(0, 0, desc.Width, desc.Height),
                ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

unsafe
{
      byte* sourceptr = (byte*)sourcedata.Scan0;  //B,G,R
      byte* descptr = (byte*)descdata.Scan0;
      for (int x = 0; x < source.Height; x++)
      {
           for (int y = 0; y < source.Width; y++)
           {
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                *(descptr++) = *sourceptr;
                sourceptr += 3;
            }
            sourceptr += sourcedata.Stride - source.Width * 3;
            descptr += descdata.Stride - desc.Width * 3;
       }
}
source.UnlockBits(sourcedata);
desc.UnlockBits(descdata);

4。平均转换灰度

Bitmap desc = new Bitmap(source.Width, source.Height);
BitmapData sourcedata = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), 
                ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
BitmapData descdata = desc.LockBits(new Rectangle(0, 0, desc.Width, desc.Height),
                ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

unsafe
{
      byte* sourceptr = (byte*)sourcedata.Scan0;  //B,G,R
      byte* descptr = (byte*)descdata.Scan0;
      for (int x = 0; x < source.Height; x++)
      {
           for (int y = 0; y < source.Width; y++)
           {
                *(descptr) = *(descptr + 1) = *(descptr + 2) = (byte)((*sourceptr + *(sourceptr + 1) + *(sourceptr + 2)) / 3);
                descptr += 3;
                sourceptr += 3;
            }
            sourceptr += sourcedata.Stride - source.Width * 3;
            descptr += descdata.Stride - desc.Width * 3;
       }
}
source.UnlockBits(sourcedata);
desc.UnlockBits(descdata);

5。加权平均转换灰度

Bitmap desc = new Bitmap(source.Width, source.Height);
BitmapData sourcedata = source.LockBits(new Rectangle(0, 0, source.Width, source.Height), 
                ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
BitmapData descdata = desc.LockBits(new Rectangle(0, 0, desc.Width, desc.Height),
                ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);

unsafe
{
      byte* sourceptr = (byte*)sourcedata.Scan0;  //B,G,R
      byte* descptr = (byte*)descdata.Scan0;
      for (int x = 0; x < source.Height; x++)
      {
           for (int y = 0; y < source.Width; y++)
           {
                *(descptr) = *(descptr + 1) = *(descptr + 2) = (byte)(*sourceptr * 0.11 + *(sourceptr + 1) * 0.58 + *(sourceptr + 2) * 0.31);
                descptr += 3;
                sourceptr += 3;
            }
            sourceptr += sourcedata.Stride - source.Width * 3;
            descptr += descdata.Stride - desc.Width * 3;
       }
}
source.UnlockBits(sourcedata);
desc.UnlockBits(descdata);