這個表達式的算法是什麼意思?圖形寶石四。使用Neigborhood地圖進行二值圖像細化
p = ((p<<1)&0666) | ((q<<3)&0110) | (Image->scanLine(y+1)[x+1] != 0);
算法「二值圖像細化使用鄰域地圖」一書中「圖形寶石IV」:
static int masks[] = {0200, 0002, 0040, 0010};
uchar delete_[512] =
{
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,1,0,0,1,1, 0,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,1,1,1,0,1,1, 0,0,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 1,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 1,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,1,1,1,0,1,1, 1,1,1,1,1,1,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,0,0,0,0,0,0, 1,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,1,1,1,0,1,1, 1,1,1,1,1,1,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,1,1,1,0,1,1, 0,0,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0, 0,0,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,0,0,0,0,0,0, 1,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,1,1,1,0,1,1, 1,1,1,1,1,1,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,0,0,0,0,0,0, 1,1,1,1,0,0,1,1,
0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,
1,0,1,1,1,0,1,1, 1,1,1,1,1,1,1,1
};
int xsize, ysize;
int x, y;
int i;
int count = 1;
int p, q;
uchar *qb;
int m;
xsize = Image->width();
ysize = Image->height();
qb = (uchar*) malloc (xsize*sizeof(uchar));
qb[xsize-1] = 0;
while(count)
{
count = 0;
for (i = 0; i < 4; ++i)
{
m = masks[i];
p = Image->scanLine(0)[0] != 0;
for (x = 0; x < xsize-1; ++x)
qb[x] = p = ((p<<1)&0006) | (Image->scanLine(0)[x+1] != 0);
// Scan image for pixel deletion candidates.
for (y = 0; y < ysize-1; ++y)
{
q = qb[0];
p = ((q<<3)&0110) | (Image->scanLine(y+1)[0] != 0);
for (x = 0; x < xsize-1; ++x)
{
q = qb[x];
p = ((p<<1)&0666) | ((q<<3)&0110) | (Image->scanLine(y+1)[x+1] != 0);
qb[x] = p;
if ((p&m)==0 && delete_[p])
{
count++;
Image->scanLine(y)[x] = 0;
}
}
現在我們看到的命名常數的重要性。 – GManNickG 2010-02-14 22:04:22
C程序員認爲有意義的標識符名稱會導致執行時間不足:) – 2010-02-14 22:13:55
對於那些讀過本書的人來說這個答案 – zxcvbn900 2010-02-14 22:22:05