/// <summary>
/// 使用 hilditch 算法进行细化
/// </summary>
public unsafe void Thinning(Byte foreground = 255)
{
Byte * start = this.Start;
Int32 width = this.Width;
Int32 height = this.Height;
Int32 *list = stackalloc Int32[8];
Byte background = (Byte)(255 - foreground);
Int32 length = this.Length;
using (ImageU8 mask = new ImageU8(this.Width, this.Height))
{
mask.Fill(0);
Boolean loop = true;
while (loop == true)
{
loop = false;
for (Int32 r = 1; r < height - 1; r++)
{
for (Int32 c = 1; c < width - 1; c++)
{
Byte *p = start + r * width + c;
// 条件1：p 必须是前景点
if (*p != foreground)
{
continue;
}
// p3 p2 p1
// p4 p p0
// p5 p6 p7
// list 存储的是补集，即前景点为0，背景点为1，以方便联结数的计算
FillNeighbors(p, list, width, foreground);
// 条件2：p0,p2,p4,p6 不皆为前景点
if (list[0] == 0 && list[2] == 0 && list[4] == 0 && list[6] == 0)
{
continue;
}
// 条件3: p0~p7至少两个是前景点
Int32 count = 0;
for (int i = 0; i < 8; i++)
{
count += list[i];
}
if (count > 6)
{
continue;
}
// 条件4：联结数等于1
if (DetectConnectivity(list) != 1)
{
continue;
}
// 条件5: 假设p2已标记删除，则令p2为背景，不改变p的联结数
if (mask[r - 1, c] == 1)
{
list[2] = 1;
if (DetectConnectivity(list) != 1)
{
continue;
}
list[2] = 0;
}
// 条件6: 假设p4已标记删除，则令p4为背景，不改变p的联结数
if (mask[r, c - 1] == 1)
{
list[4] = 1;
if (DetectConnectivity(list) != 1)
{
continue;
}
}
mask[r, c] = 1; // 标记删除
loop = true;
}
}
for (int i = 0; i < length; i++)
{
if (mask[i] == 1)
{
this[i] = background;
}
}
}
}
}
public unsafe void SkeletonizeByMidPoint(Byte foreground = 255)
{
using (ImageU8 mask = new ImageU8(this.Width, this.Height))
{
mask.Fill(0);
Int32 width = this.Width;
Int32 height = this.Height;
for (Int32 r = 0; r < height; r++)
{
Int32 lineStart = -1;
for (Int32 c = 0; c < width; c++)
{
if (this[r, c] == foreground)
{
if (lineStart == -1)
{
lineStart = c;
}
}
else
{
if (lineStart != -1)
{
mask[r, (lineStart + c) / 2] = 1;
lineStart = -1;
}
}
}
}
for (Int32 c = 0; c < width; c++)
{
Int32 lineStart = -1;
for (Int32 r = 0; r < height; r++)
{
if (this[r, c] == foreground)
{
if (lineStart == -1)
{
lineStart = r;
}
}
else
{
if (lineStart != -1)
{
mask[(lineStart + r) / 2, c] = 1;
lineStart = -1;
}
}
}
}
Byte bg = (Byte)(255 - foreground);
Int32 length = this.Length;
for (int i = 0; i < length; i++)
{
if (mask[i] == 1)
{
this[i] = foreground;
}
else
{
this[i] = bg;
}
}
}
}
