轉自：http://blog.csdn.net/byxdaz/archive/2010/06/02/5642669.aspx

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細化算法通常和骨骼化、骨架化算法是相同的意思，也就是thin算法或者skeleton算法。雖然很多圖像處理的教材上不是這么寫的，具體原因可以看這篇論文，Louisa Lam, Seong-Whan Lee, Ching Y. Suen，“Thinning Methodologies-A Comprehensive Survey ”，IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE, VOL. 14, NO. 9, SEPTEMBER 1992 ，總結了幾乎所有92年以前的經典細化算法。

函數：void cvThin( IplImage* src, IplImage* dst, int iterations=1)
功能：將IPL_DEPTH_8U型二值圖像進行細化
參數：src，原始IPL_DEPTH_8U型二值圖像
dst，目標存儲空間，必須事先分配好，且和原圖像大小類型一致
iterations，迭代次數
參考文獻：T. Y. Zhang and C. Y. Suen, “A fast parallel algorithm for thinning digital patterns,” Comm. ACM, vol. 27, no. 3, pp. 236-239, 1984.

void cvThin( IplImage* src, IplImage* dst, int iterations=1)
{
?CvSize size = cvGetSize(src);

?cvCopy(src, dst);
??? int n = 0,i = 0,j = 0;
?for(n=0; n<iterations; n++)
?{
? IplImage* t_image = cvCloneImage(dst);
? for(i=0; i<size.height;? i++)
? {
?? for(j=0; j<size.width; j++)
?? {
??? if(CV_IMAGE_ELEM(t_image,byte,i,j)==1)
??? {
???? int ap=0;
???? int p2 = (i==0)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j);
???? int p3 = (i==0 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j+1);
???? if (p2==0 && p3==1)
???? {
????? ap++;
???? }
???? int p4 = (j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i,j+1);
???? if(p3==0 && p4==1)
???? {
????? ap++;
???? }
???? int p5 = (i==size.height-1 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j+1);
???? if(p4==0 && p5==1)
???? {
????? ap++;
???? }
???? int p6 = (i==size.height-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j);
???? if(p5==0 && p6==1)
???? {
????? ap++;
???? }
???? int p7 = (i==size.height-1 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j-1);
???? if(p6==0 && p7==1)
???? {
????? ap++;
???? }
???? int p8 = (j==0)?0:CV_IMAGE_ELEM(t_image,byte,i,j-1);
???? if(p7==0 && p8==1)
???? {
????? ap++;
???? }
???? int p9 = (i==0 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i-1,j-1);
???? if(p8==0 && p9==1)
???? {
????? ap++;
???? }
???? if(p9==0 && p2==1)
???? {
????? ap++;
???? }
???? if((p2+p3+p4+p5+p6+p7+p8+p9)>1 && (p2+p3+p4+p5+p6+p7+p8+p9)<7)
???? {
????? if(ap==1)
????? {
?????? if(!(p2 && p4 && p6))
?????? {
??????? if(!(p4 && p6 && p8))
??????? {
???????? CV_IMAGE_ELEM(dst,byte,i,j)=0;
??????? }
?????? }
????? }
???? }

??? }
?? }
? }
? cvReleaseImage(&t_image);
? t_image = cvCloneImage(dst);
? for(i=0; i<size.height;? i++)
? {
?? for(int j=0; j<size.width; j++)
?? {
??? if(CV_IMAGE_ELEM(t_image,byte,i,j)==1)
??? {
???? int ap=0;
???? int p2 = (i==0)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j);
???? int p3 = (i==0 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte, i-1, j+1);
???? if (p2==0 && p3==1)
???? {
????? ap++;
???? }
???? int p4 = (j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i,j+1);
???? if(p3==0 && p4==1)
???? {
????? ap++;
???? }
???? int p5 = (i==size.height-1 || j==size.width-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j+1);
???? if(p4==0 && p5==1)
???? {
????? ap++;
???? }
???? int p6 = (i==size.height-1)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j);
???? if(p5==0 && p6==1)
???? {
????? ap++;
???? }
???? int p7 = (i==size.height-1 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i+1,j-1);
???? if(p6==0 && p7==1)
???? {
????? ap++;
???? }
???? int p8 = (j==0)?0:CV_IMAGE_ELEM(t_image,byte,i,j-1);
???? if(p7==0 && p8==1)
???? {
????? ap++;
???? }
???? int p9 = (i==0 || j==0)?0:CV_IMAGE_ELEM(t_image,byte,i-1,j-1);
???? if(p8==0 && p9==1)
???? {
????? ap++;
???? }
???? if(p9==0 && p2==1)
???? {
????? ap++;
???? }
???? if((p2+p3+p4+p5+p6+p7+p8+p9)>1 && (p2+p3+p4+p5+p6+p7+p8+p9)<7)
???? {
????? if(ap==1)
????? {
?????? if(p2*p4*p8==0)
?????? {
??????? if(p2*p6*p8==0)
??????? {
???????? CV_IMAGE_ELEM(dst, byte,i,j)=0;
??????? }
?????? }
????? }
???? }???????????????????
??? }

?? }

? }???????????
? cvReleaseImage(&t_image);
?}

}

//使用舉例

#include "cxcore.h"
#include "cv.h"
#include "highgui.h"

int main(int argc, char* argv[])
{
?if(argc!=2)
?{
? return 0;
?}
?IplImage *pSrc = NULL,*pDst = NULL,*pTmp = NULL;

//傳入一個灰度圖像
?pSrc = cvLoadImage(argv[1],CV_LOAD_IMAGE_GRAYSCALE);
?if(!pSrc)
?{
? return 0;
?}
?pTmp = cvCloneImage(pSrc);
??? pDst = cvCreateImage(cvGetSize(pSrc),pSrc->depth,pSrc->nChannels);
?cvZero(pDst);
?cvThreshold(pSrc,pTmp,128,1,CV_THRESH_BINARY_INV);//做二值處理，將圖像轉換成0，1格式
?//cvSaveImage("c://Threshold.bmp",pTmp,0);
?cvThin(pTmp,pDst,8);//細化，通過修改iterations參數進一步細化
?cvNamedWindow("src",1);
?cvNamedWindow("dst",1);
?cvShowImage("src",pSrc);
?//將二值圖像轉換成灰度，以便顯示
?int i = 0,j = 0;
?CvSize size = cvGetSize(pDst);
?for(i=0; i<size.height;? i++)
?{
? for(j=0; j<size.width; j++)
? {
?? if(CV_IMAGE_ELEM(pDst,uchar,i,j)==1)
?? {
??? CV_IMAGE_ELEM(pDst,uchar,i,j) = 0;
?? }
?? else
?? {
??? CV_IMAGE_ELEM(pDst,uchar,i,j) = 255;
?? }
? }
?}
?//cvSaveImage("c://thin.bmp",pDst);
?cvShowImage("dst",pDst);
?cvWaitKey(0);
??? cvReleaseImage(&pSrc);
?cvReleaseImage(&pDst);
?cvReleaseImage(&pTmp);
?cvDestroyWindow("src");
?cvDestroyWindow("dst");
?return 0;
}

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