bwlabel.cpp

////////////bwlabel.cpp#include "cv.h"#include "highgui.h"#define     NO_OBJECT       0#define     MIN(x, y)       (((x) < (y)) ? (x) : (y))#define     ELEM(img, r, c) (CV_IMAGE_ELEM(img, unsigned char, r, c))#define     ONETWO(L, r, c, col) (L[(r) * (col) + c])int find( int set[], int x ){int r = x;while ( set[r] != r )r = set[r];return r;}/*labeling scheme+-+-+-+|D|C|E|+-+-+-+|B|A| |+-+-+-+| | | |+-+-+-+A is the center pixel of a neighborhood.  In the 3 versions ofconnectedness:4:  A connects to B and C6:  A connects to B, C, and D8:  A connects to B, C, D, and E*////////////////////////////////by yysdsyl////input:img     --  gray image//      n       --  n connectedness//      labels  --  label of each pixel, labels[row * col]//output:  number of connected regions//////email:[e-mail] bwlabel(IplImage* img, int n, int* labels){if(n != 4 && n != 8)n = 4;int nr = img->height;int nc = img->width;int total = nr * nc;// resultsmemset(labels, 0, total * sizeof(int));int nobj = 0;                               // number of objects found in image// other variables                             int* lset = new int[total];   // label tablememset(lset, 0, total * sizeof(int));int ntable = 0;for( int r = 0; r < nr; r++ ) {for( int c = 0; c < nc; c++ ) {            if ( ELEM(img, r, c) )   // if A is an object{               // get the neighboring pixels B, C, D, and Eint B, C, D, E;if ( c == 0 ) B = 0; else B = find( lset, ONETWO(labels, r, c - 1, nc) );if ( r == 0 ) C = 0; else C = find( lset, ONETWO(labels, r - 1, c, nc) );if ( r == 0 || c == 0 ) D = 0; else D = find( lset, ONETWO(labels, r - 1, c - 1, nc) );if ( r == 0 || c == nc - 1 ) E = 0;else E = find( lset, ONETWO(labels, r - 1, c + 1, nc) );if ( n == 4 ) {// apply 4 connectednessif ( B && C ) {        // B and C are labeledif ( B == C )ONETWO(labels, r, c, nc) = B;else {lset[C] = B;ONETWO(labels, r, c, nc) = B;}} else if ( B )             // B is object but C is notONETWO(labels, r, c, nc) = B;else if ( C )               // C is object but B is notONETWO(labels, r, c, nc) = C;else {                      // B, C, D not object - new object//   label and put into tablentable++;ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;}} else if ( n == 6 ) {// apply 6 connected nessif ( D )                    // D object, copy label and move onONETWO(labels, r, c, nc) = D;else if ( B && C ) {        // B and C are labeledif ( B == C )ONETWO(labels, r, c, nc) = B;else {int tlabel = MIN(B,C);lset[B] = tlabel;lset[C] = tlabel;ONETWO(labels, r, c, nc) = tlabel;}} else if ( B )             // B is object but C is notONETWO(labels, r, c, nc) = B;else if ( C )               // C is object but B is notONETWO(labels, r, c, nc) = C;else {                      // B, C, D not object - new object//   label and put into tablentable++;ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;}}else if ( n == 8 ) {// apply 8 connectednessif ( B || C || D || E ) {int tlabel = B;if ( B ) tlabel = B;else if ( C ) tlabel = C;else if ( D ) tlabel = D;else if ( E ) tlabel = E;ONETWO(labels, r, c, nc) = tlabel;if ( B && B != tlabel ) lset[B] = tlabel;if ( C && C != tlabel ) lset[C] = tlabel;if ( D && D != tlabel ) lset[D] = tlabel;if ( E && E != tlabel ) lset[E] = tlabel;} else {//   label and put into tablentable++;ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;}}} else {ONETWO(labels, r, c, nc) = NO_OBJECT;      // A is not an object so leave it}}}// consolidate component tablefor( int i = 0; i <= ntable; i++ )lset[i] = find( lset, i );                                                                                                 // run image through the look-up tablefor( int r = 0; r < nr; r++ )for( int c = 0; c < nc; c++ )ONETWO(labels, r, c, nc) = lset[ ONETWO(labels, r, c, nc) ];// count up the objects in the imagefor( int i = 0; i <= ntable; i++ )lset[i] = 0;for( int r = 0; r < nr; r++ )for( int c = 0; c < nc; c++ )lset[ ONETWO(labels, r, c, nc) ]++;// number the objects from 1 through n objectsnobj = 0;lset[0] = 0;for( int i = 1; i <= ntable; i++ )if ( lset[i] > 0 )lset[i] = ++nobj;// run through the look-up table againfor( int r = 0; r < nr; r++ )for( int c = 0; c < nc; c++ )ONETWO(labels, r, c, nc) = lset[ ONETWO(labels, r, c, nc) ];//delete[] lset;return nobj;}