//灰度化
private Bitmap bitmapGray(Bitmap bitmap, GrayMode mode)
{
if (bitmap == null)
{
return(null);
}
Bitmap newBitmap = bitmap.Clone() as Bitmap;
int width = newBitmap.Width;
int height = newBitmap.Height;
BitmapData bitmapData = newBitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadOnly, newBitmap.PixelFormat);
int stride = bitmapData.Stride;//stride是一整行的宽度 32色图情况下为width*4
IntPtr ptr = bitmapData.Scan0;
byte[] src = new byte[stride * height];
Marshal.Copy(ptr, src, 0, stride * height);
for (int i = 0; i < height; i++)
{
for (int j = 0; j < stride; j += 4)
{
int k = i * stride;
switch (mode)
{
case GrayMode.COMPONENT_RED:
src[k + j + 1] = src[k + j + 2] = src[k + j];
break;
case GrayMode.COMPONENT_GREEN:
src[k + j] = src[k + j + 2] = src[k + j + 1];
break;
case GrayMode.COMPONENT_BLUE:
src[k + j] = src[k + j + 1] = src[k + j + 2];
break;
case GrayMode.AVERAGE_RGB:
src[k + j] = src[k + j + 1] = src[k + j + 2] = (byte)((src[k + j] + src[k + j + 1] + src[k + j + 2]) / 3);
break;
case GrayMode.MAX_RGB:
src[k + j] = src[k + j + 1] = src[k + j + 2] = Math.Max(Math.Max(src[k + j], src[k + j + 1]), src[k + j + 2]);
break;
case GrayMode.WEIGHT_RGB:
byte sum = (byte)(src[k + j] * 0.299 + src[k + j + 1] * 0.578 + src[k + j + 2] * 0.114);
src[k + j + 1] = src[k + j + 2] = src[k + j] = sum;
break;
}
}
}
Marshal.Copy(src, 0, ptr, stride * height);
newBitmap.UnlockBits(bitmapData);
return(newBitmap);
}
/// <summary>
/// 获取灰度值位图(内存处理方法)
/// </summary>
/// <param name="bitmap">转换位图</param>
/// <param name="mode">处理模式</param>
/// <returns>处理结果位图</returns>
public static Bitmap GrayscaleBitmap(Bitmap bitmap, GrayMode mode = GrayMode.Perceived)
{
if (bitmap == null)
{
return(null);
}
Bitmap srcBitmap = (Bitmap)bitmap.Clone();
int width = srcBitmap.Width, height = srcBitmap.Height;
Rectangle rect = new Rectangle(0, 0, width, height);
//将Bitmap锁定到系统内存中,获得BitmapData
BitmapData srcBmData = srcBitmap.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
//创建Bitmap
Bitmap dstBitmap = new Bitmap(width, height, PixelFormat.Format8bppIndexed);
BitmapData dstBmData = dstBitmap.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format8bppIndexed);
// get palette
ColorPalette cp = dstBitmap.Palette;
// init palette
for (int i = 0; i < 256; i++)
{
cp.Entries[i] = Color.FromArgb(i, i, i);
}
dstBitmap.Palette = cp;
//位图中第一个像素数据的地址。它也可以看成是位图中的第一个扫描行
IntPtr srcPtr = srcBmData.Scan0, dstPtr = dstBmData.Scan0;
//将Bitmap对象的信息存放到byte数组中
int src_bytes = srcBmData.Stride * height, dst_bytes = dstBmData.Stride * height;
byte[] srcValues = new byte[src_bytes], dstValues = new byte[dst_bytes];
//复制GRB信息到byte数组
Marshal.Copy(srcPtr, srcValues, 0, src_bytes);
Marshal.Copy(dstPtr, dstValues, 0, dst_bytes);
//根据Y=0.299*R+0.114*G+0.587B,Y为亮度
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
//只处理每行中图像像素数据,舍弃未用空间
//注意位图结构中RGB按BGR的顺序存储
int k = 3 * j;
byte r = srcValues[i * srcBmData.Stride + k + 2];
byte g = srcValues[i * srcBmData.Stride + k + 1];
byte b = srcValues[i * srcBmData.Stride + k];
// 灰度值提取
byte temp = 0;
switch (mode)
{
case GrayMode.AverageMethod:
temp = (byte)((r + g + b) / 3);
break;
case GrayMode.Perceived:
temp = (byte)(r * 0.299 + g * 0.587 + b * 0.114);
break;
case GrayMode.TakeGreen:
temp = g;
break;
}
dstValues[i * dstBmData.Stride + j] = temp;
}
}
Marshal.Copy(dstValues, 0, dstPtr, dst_bytes);
//解锁位图
srcBitmap.UnlockBits(srcBmData);
dstBitmap.UnlockBits(dstBmData);
return(dstBitmap);
}
