C#图像灰度级拉伸的方法

本文实例讲述了c#图像灰度级拉伸的方法。分享给大家供大家参考。具体如下：

//定义图像灰度拉伸函数
private static bitmap graylp (bitmap a)
{
  rectangle rect = new rectangle(0, 0, a.width, a.height);
  system.drawing.imaging.bitmapdata srcdata = a.lockbits(rect, system.drawing.imaging.imagelockmode.readwrite, a.pixelformat);
  intptr ptr = srcdata.scan0;
  int bytes = 0;
  if (a.pixelformat == system.drawing.imaging.pixelformat.format8bppindexed)
  { bytes = a.width * a.height; }
  else { bytes = a.width * a.height * 3; }
  byte[] grayvalues = new byte[bytes];
  system.runtime.interopservices.marshal.copy(ptr, grayvalues, 0, bytes);
  byte n = 255, m = 0;
  double p;
  //计算最大和最小灰度级
  for (int i = 0; i < bytes; i++)
  {
   //计算最小灰度级
   if (n > grayvalues[i])
   {
     n = grayvalues[i];
   }        
   //计算最大灰度级
   if (m < grayvalues[i])
   {
     m = grayvalues[i];
   }
  }
  //得到斜率
  p = 255.0 / (m - n);
  //灰度拉伸
  for (int i = 0; i < bytes; i++)
  {
   grayvalues[i] = (byte)(p * (grayvalues[i] - n) + 0.5);
  }
  system.runtime.interopservices.marshal.copy(grayvalues, 0, ptr, bytes);
  a.unlockbits(srcdata);
  return a;
}

希望本文所述对大家的c#程序设计有所帮助。