} // end of Relief
/// <summary>
/// 对图像进行灰度浮雕处理
/// </summary>
/// <param name="b">位图流</param>
/// <param name="angle">角度[0, 360]</param>
/// <returns></returns>
public Bitmap Emboss(Bitmap b, int angle)
{
// 角度转弧度
double radian = (double)angle * Math.PI / 180.0;
// 每一权的弧度间隔
double pi4 = Math.PI / 4.0;
// 对图像进行卷积变换
Matrix3x3 m = new Matrix3x3();
m.TopLeft = Convert.ToInt32(Math.Cos(radian + pi4) * 256);
m.TopMid = Convert.ToInt32(Math.Cos(radian + 2.0 * pi4) * 256);
m.TopRight = Convert.ToInt32(Math.Cos(radian + 3.0 * pi4) * 256);
m.MidLeft = Convert.ToInt32(Math.Cos(radian) * 256);
m.Center = 0;
m.MidRight = Convert.ToInt32(Math.Cos(radian + 4.0 * pi4) * 256);
m.BottomLeft = Convert.ToInt32(Math.Cos(radian - pi4) * 256);
m.BottomMid = Convert.ToInt32(Math.Cos(radian - 2.0 * pi4) * 256);
m.BottomRight = Convert.ToInt32(Math.Cos(radian - 3.0 * pi4) * 256);
m.Scale = 256;
m.Offset = 128;
b = m.Convolute(b);
// 对图像进行灰度变换
GrayProcessing gp = new GrayProcessing();
b = gp.Gray(b, GrayProcessing.GrayMethod.WeightAveraging);
return(b);
} // end of Emboss
} // end of Thresholding
/// <summary>
/// 自适应阈值
/// </summary>
/// <param name="b">位图流</param>
/// <returns></returns>
public Bitmap AutoFitThreshold(Bitmap b)
{
// 图像灰度化
GrayProcessing gp = new GrayProcessing();
b = gp.Gray(b, GrayMethod.WeightAveraging);
// 建立直方图，并获取灰度统计信息
Histogram histogram = new Histogram(b);
int [] GrayLevel = histogram.Red.Value;
int peak1, peak2, valley;
int peak1Index, peak2Index, valleyIndex;
// 取双峰
peak1 = peak2 = GrayLevel[0];
peak1Index = peak2Index = 0;
for (int i = 1; i < 256; i++)
{
// 如果产生新的高峰，则将第一峰退居第二峰，新的高峰升为第一峰
if (GrayLevel[i] > peak1)
{
peak2 = peak1;
peak2Index = peak1Index;
peak1 = GrayLevel[i];
peak1Index = i;
}
} // i
// 判断两个峰值索引
int max = peak1Index;
int min = peak2Index;
if (max < min)
{
int t = max;
max = min;
min = t;
}
// 取峰谷
valley = GrayLevel[min];
valleyIndex = min;
for (int i = min; i < max; i++)
{
if (GrayLevel[i] < valley)
{
valley = GrayLevel[i];
valleyIndex = i;
}
} // i
// 根据找到的谷值对图像进行二值化
return(Thresholding(b, (byte)valleyIndex));
} // end of AutoFitThreshold