二值图的连通区域标记

#include <math.h>#include <stdlib.h>#include <stdio.h>//#include <memory.h>////////////////////////////////////////////////////////////堆栈操作#define TRUE 1#define FALSE 0#define STACK_INIT_SIZE 1000#define STACK_INCRE 200#define CONNECTIVITY8 8#define CONNECTIVITY4 4typedef struct tagStack{int **base;int **top;int stacksize;}Stack;// 建立空栈，大小为STACK_INIT_SIZEStack* InitStack( void ){Stack *pStack = calloc( 1, sizeof(Stack) );pStack->base = calloc( STACK_INIT_SIZE+1, sizeof(int *) );pStack->top = pStack->base;pStack->stacksize = STACK_INIT_SIZE;return pStack;}// 判断栈是否为空int IsStackEmpty( Stack *pStack ){// 栈空的的条件是 pStack->base != NULL，且 pStack->top == pStack->baseif( pStack->top == pStack->base )return TRUE ;elsereturn FALSE ;} // 把元素pnElement压入栈中void Push( Stack *pStack , int *pnElement ){// 若栈满，则增加空间// 存在BUGif( pStack->top - pStack->base >= pStack->stacksize ){pStack->base = (int **)realloc( pStack->base, (pStack->stacksize+STACK_INCRE)*sizeof(int *) );pStack->top = pStack->base + pStack->stacksize;pStack->stacksize += STACK_INCRE;}++ pStack->top;*(pStack->top) = pnElement;}// 删除栈顶元素，并用pnElement返回其值void Pop( Stack *pStack, int *pnElement ) {if( pStack->top == pStack->base && *(pStack->top)==NULL  )printf("栈为空！\n");else{memcpy( pnElement, *(pStack->top), 4*sizeof(int) );(pStack->top)--;}}// 销毁堆栈void DestroyStack( Stack *pStack ){free( pStack->base );pStack->top = pStack->base = NULL ;pStack->stacksize = 0;free( pStack ), pStack=NULL;}/************************************************************************//* 函数：BWLabel功能：实现二值图像的连通区域标记参数：pnBW---指向二值图像数据，要求像素值为0、1pnBWLabel---指向标记后的图像nImageWidth、nImageHeight---图像高宽nMode---邻域的连接模式：8为八连通，4为四连通返回：图像中区域数目*//************************************************************************/int BWLabel( unsigned char *pnBW, unsigned char *pnBWLabel, int nImageWidth, int nImageHeight, int nMode ){int i=0,j=0;int k=0, m=0, n=0, L=0, R=0, LL=0, RR=0, N=0, X=0, nFlag=0;int *pnBWPadded=NULL, nWidthPadded=nImageWidth+2, nHeightPadded=nImageHeight+2;int *pnSegNumPerLine=NULL, **pnSegments=NULL, *pnSegmentTemp=NULL;Stack *pStack = NULL;if ( nMode!=CONNECTIVITY4 && nMode!=CONNECTIVITY8 ){printf("必须制定nMode的值，必须是8或者4！");exit(-1);}//加边，补零pnBWPadded = calloc( nWidthPadded*nHeightPadded, sizeof(int) );//for ( i=0; i<nImageHeight; i++ )//memcpy( pnBWPadded+(i+1)*nWidthPadded+1, pnBW+i*nImageWidth, nImageWidth*sizeof(int) );for ( i=0; i<nImageHeight; i++ )for ( j=0; j<nImageWidth; j++ ){pnBWPadded[(i+1)*nWidthPadded+j+1]=pnBW[i*nImageWidth+j];}//统计每一行线段的数目，存入pnLineNumberpnSegNumPerLine = calloc( nHeightPadded, sizeof(int) );for ( i=0; i<nImageHeight; i++ )for ( j=0; j<nWidthPadded-1; j++ ){if ( pnBWPadded[(i+1)*nWidthPadded+j]==0 && pnBWPadded[(i+1)*nWidthPadded+j+1]==1 )pnSegNumPerLine[i+1]++;}//为每一行的线段端点存储分配空间pnSegments = calloc( nHeightPadded, sizeof(int *) );for ( i=0; i<nHeightPadded; i++ )pnSegments[i] = calloc( pnSegNumPerLine[i]*4, sizeof(int) );//扫描标记/*pnSegment矩阵中的数据结构*//*---------------------------  |行号|左端点|右端点|标志位|  ---------------------------  |行号|左端点|右端点|标志位|  ---------------------------  |行号|左端点|右端点|标志位|  ---------------------------  |行号|左端点|右端点|标志位|  ---------------------------*/for ( i=1; i<nHeightPadded-1; i++ ){n = 0;for ( j=0; j<nWidthPadded-1; j++ ){if ( pnBWPadded[i*nWidthPadded+j]==1 ){for ( k=j+1; k<nWidthPadded; k++ ){if ( pnBWPadded[i*nWidthPadded+k]==0 )break;}pnSegments[i][n*4  ] = i;  //记录行号pnSegments[i][n*4+1] = j;  //记录左端点pnSegments[i][n*4+2] = k-1;//记录右端点n++;j = k;}}}pStack = InitStack();//初始化堆栈N = 1;//区域的编号for ( i=1; i<nHeightPadded-1; i++ ){for ( j=0; j<pnSegNumPerLine[i]; j++ ){//线段未被标记且未被扫描，即新的一段if ( pnSegments[i][j*4+3]==0 ){pnSegmentTemp = &pnSegments[i][j*4];//*(pStack->top) = pnSegmentTemp;pnSegmentTemp[3] = -1;//标志位置-1表示入栈Push( pStack, pnSegmentTemp );//入栈Loop:pnSegmentTemp = *(pStack->top);X = pnSegmentTemp[0];//行号L = pnSegmentTemp[1];//左端点R = pnSegmentTemp[2];//右端点//区分是八连通还是四连通LL = (nMode==CONNECTIVITY8)?(L-1):L;RR = (nMode==CONNECTIVITY8)?(R+1):R;nFlag = 0;//扫描上一行看是否存在未标记的邻接线段，存在，nFlag=1，将邻接段压入堆栈for ( m=0; m<pnSegNumPerLine[X-1]; m++ ){if ( pnSegments[X-1][m*4+1]<=RR && pnSegments[X-1][m*4+2]>=LL && pnSegments[X-1][m*4+3]==0 ){pnSegments[X-1][m*4+3] = -1;Push( pStack, &pnSegments[X-1][m*4] );nFlag = 1;}}//扫描下一行看是否存在邻接线段，存在，nFlag=1，将邻接段压入堆栈for ( n=0; n<pnSegNumPerLine[X+1]; n++ ){if ( pnSegments[X+1][n*4+1]<=RR && pnSegments[X+1][n*4+2]>=LL && pnSegments[X+1][n*4+3]==0 ){pnSegments[X+1][n*4+3] = -1;Push( pStack, &pnSegments[X+1][n*4] );nFlag = 1;}}//表明该段邻接段均已标记//或者不存在邻接段if ( nFlag==0 ){if ( IsStackEmpty( pStack ) )//栈为空，继续标记下一个连通区域{N++;continue;}else{(*(pStack->top))[3] = N;//栈为不空，标记当前连通区域Pop( pStack, pnSegmentTemp );//将其从堆栈中弹出//栈为空，表明当前连通区域标记完毕//开始下一个连通区域的标记if ( IsStackEmpty( pStack ) ){N++;continue;}elsegoto Loop;//栈不为空，继续处理栈顶元素}}elsegoto Loop;//继续处理栈顶元素}}}//依据pnSegments中各个标记位，标记二值图像for ( i=0; i<nImageHeight; i++ )for ( j=0; j<pnSegNumPerLine[i+1]; j++ )for ( k=pnSegments[i+1][j*4+1]; k<=pnSegments[i+1][j*4+2]; k++ )pnBWLabel[i*nImageWidth+k-1] = pnSegments[i+1][j*4+3];free( pnBWPadded ), pnBWPadded = NULL;free( pnSegNumPerLine ), pnSegNumPerLine = NULL;for ( i=0; i<nHeightPadded; i++ ){if ( pnSegments[i]!=NULL )free(pnSegments[i]), pnSegments[i]=NULL;}free(pnSegments), pnSegments=NULL;DestroyStack( pStack );return N-1;}

实现过程：

1. 在图像四周添加宽度为1像素，值为0 的边

2. 统计每一行线段数，将每一行的所有线段的起始位置与终点位置记录下来

3. 遍历每一条线段，检测上一行和下一行的线段端点，判断是否有线段与当前线段相连通，若有且未被标记，则将该线段放入栈中，并将当前的线段出栈并标记。直到栈为空，则一个区域被标记好，标记数加一。