int otsu (unsigned char *image, int rows, int cols, int x0, int y0,
int dx, int dy, int vvv)
{
unsigned char
*np;
// 图像指针
int thresholdValue=1;
// 阈值
int
ihist[256];
// 图像直方图，256个点
int i, j,
k;
// various counters
int n, n1, n2, gmin, gmax;
double m1, m2, sum, csum, fmax, sb;
// 对直方图置零...
memset(ihist, 0, sizeof(ihist));
gmin=255; gmax=0;
// 生成直方图
for (i = y0 + 1; i < y0 + dy - 1; i++)
{
np =
&image[i*cols+x0+1];
for (j = x0
+ 1; j < x0 + dx - 1; j++) {
ihist[*np]++;
if(*np > gmax) gmax=*np;
if(*np < gmin) gmin=*np;
np++;
}
}
// set up everything
sum = csum = 0.0;
n = 0;
for (k = 0; k <= 255; k++) {
sum +=
(double) k * (double)
ihist[k];
n +=
ihist[k];
}
if (!n) {
// if n has
no value, there is problems...
fprintf
(stderr, "NOT NORMAL thresholdValue = 160\n");
return
(160);
}
// do the otsu global thresholding
method
fmax = -1.0;
n1 = 0;
for (k = 0; k < 255; k++) {
n1 +=
ihist[k];
if (!n1) {
continue; }
n2 = n -
n1;
if (n2 == 0)
{ break; }
csum +=
(double) k *ihist[k];
m1 = csum /
n1;
m2 = (sum -
csum) / n2;
sb =
(double) n1 *(double) n2 *(m1 - m2) * (m1 - m2);
if (sb >
fmax) {
fmax = sb;
thresholdValue = k;
}
}
// at this point we have our thresholding
value
// debug code to display thresholding
values
if ( vvv & 1 )
fprintf(stderr,"# OTSU: thresholdValue = %d
gmin=%d gmax=%d\n",
thresholdValue, gmin, gmax);
return(thresholdValue);
}
Trackback:
http://tb.blog.csdn.net/TrackBack.aspx?PostId=92086