c# Emgucv 图像旋转
private Bitmap rotate(Bitmap bmp, double alpha, int Dest_w, int Dest_h)
{
Image
BitmapData Src_Data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
int Src_h = bmp.Height;
int Src_w = bmp.Width;
unsafe
{
int Src_tride = Src_Data.Stride;
System.IntPtr Scan0 = Src_Data.Scan0;
byte* p_Src = (byte*)(void*)Scan0;
// int Des_tride = Des_Data.Stride;
// System.IntPtr Des = Des_Data.Scan0;
// byte* p_Des = (byte*)(void*)Des;
// byte* p_Des = (byte*)Des_Data.Scan0;
for (int y = 0; y < Dest_h; y++)
{
for (int x = 0; x < Dest_w; x++)
{
// byte Src_pix =p_Src[y * Src_tride + x * 3 + 0]; ///源图像当前像素点
//将行列数转换到坐标系下
double dest_x = x - 0.5 * Dest_w;
double dest_y = 0.5 * Dest_h - y;
//获得对应的旋转前的坐标
double src_x = dest_x * Math.Cos(alpha) - dest_y * Math.Sin(alpha);
double src_y = dest_x * Math.Sin(alpha) + dest_y * Math.Cos(alpha);
if ((src_x > -0.5 * bmp.Width + 1) && (src_x < 0.5 * bmp.Width - 1) && (src_y > -0.5 * bmp.Height + 1) && (src_y < 0.5 * Src_h - 1))
//如果在原来图像的范围内的话，将旋转前的坐标对应到图像的行和列 ,四舍五入，相当于最邻近插值
{
// double row= cvRound(0.5*Src_h-src_y);
// double col= cvRound(0.5*Src_w+src_x);
double Y = Math.Round(0.5 * Src_h - src_y);
double X = Math.Round(0.5 * Src_w + src_x);
int q11x = (int)Math.Floor(X);//%返回小于或者等于它的最大整数 3.59 变为3
int q11y = (int)Math.Ceiling(Y); //%返回大于等于它的最小整数 3.59 变为4
int q21x = (int)Math.Ceiling(X);
int q21y = (int)Math.Ceiling(Y);
int q22x = (int)Math.Ceiling(X);
int q22y = (int)Math.Floor(Y);
int q12x = (int)Math.Floor(X);
int q12y = (int)Math.Floor(Y);
int X2 = (int)Math.Ceiling(X);//% important
int X1 = (int)Math.Ceiling(X - 1);
int Y2 = (int)Math.Ceiling(Y);
int Y1 = (int)Math.Ceiling(Y - 1);//%important
double piex12 = p_Src[q12y * Src_tride + q12x * 3 + 0];//((uchar*)source_img->imageData)[q12y * source_img->widthStep + q12x];
double piex22 = p_Src[q22y * Src_tride + q22x * 3 + 0];//((uchar*)source_img->imageData)[q22y * source_img->widthStep + q22x];
double piex21 = p_Src[q21y * Src_tride + q21x * 3 + 0];//((uchar*)source_img->imageData)[q21y * source_img->widthStep + q21x];
double piex11 = p_Src[q11y * Src_tride + q11x * 3 + 0];//((uchar*)source_img->imageData)[q11y * source_img->widthStep + q11x];
double R1 = (X2 - x) * piex12 + (x - X1) * piex22;
double R2 = (X2 - x) * piex11 + (x - X1) * piex21;
double fp = ((Y2 - y) * R1 + (y - Y1) * R2);
if (fp > 125) //操作后有些值可能不是0 也不是255
fp = 255;
else
fp = 0;
byte a = (byte)Math.Round(fp);
after_rotate[y, x] = new Gray(a); //给灰度图像赋值
}
} //end for
} //end for
} //end unsafe
bmp.UnlockBits(Src_Data);
// after_rotate.UnlockBits(Des_Data);
return after_rotate.ToBitmap();
}