【zbar源码分析】确定探测图形中心点数量

static int qr_finder_centers_locate(qr_finder_center **_centers, qr_finder_edge_pt **_edge_pts, qr_reader *reader, int _width,int _height){ qr_finder_line *hlines = reader->finder_lines[0].lines; int nhlines = reader->finder_lines[0].nlines; qr_finder_line *vlines = reader->finder_lines[1].lines; int nvlines = reader->finder_lines[1].nlines; qr_finder_line **hneighbors; qr_finder_cluster *hclusters; int nhclusters; qr_finder_line **vneighbors; qr_finder_cluster *vclusters; int nvclusters; int ncenters; /*Cluster the detected lines.*/ hneighbors=(qr_finder_line **)mymalloc(SRAMEX, nhlines*sizeof(*hneighbors)); /*We require more than one line per cluster, so there are at most nhlines/2.*/ hclusters=(qr_finder_cluster *)mymalloc(SRAMEX, (nhlines>>1)*sizeof(*hclusters)); nhclusters=qr_finder_cluster_lines(hclusters,hneighbors,hlines,nhlines,0); /*We need vertical lines to be sorted by X coordinate, with ties broken by Y coordinate, for clustering purposes. We scan the image in the opposite order for cache efficiency, so sort the lines we found here.*/ qsort(vlines,nvlines,sizeof(*vlines),qr_finder_vline_cmp); vneighbors=(qr_finder_line **)mymalloc(SRAMEX, nvlines*sizeof(*vneighbors)); /*We require more than one line per cluster, so there are at most nvlines/2.*/ vclusters=(qr_finder_cluster *)mymalloc(SRAMEX, (nvlines>>1)*sizeof(*vclusters)); nvclusters=qr_finder_cluster_lines(vclusters,vneighbors,vlines,nvlines,1); /*Find line crossings among the clusters.*/ if(nhclusters>=3&&nvclusters>=3){ qr_finder_edge_pt *edge_pts; qr_finder_center *centers; int nedge_pts; int i; nedge_pts=0; for(i=0;i<nhclusters;i++)nedge_pts+=hclusters[i].nlines; for(i=0;i<nvclusters;i++)nedge_pts+=vclusters[i].nlines; nedge_pts<<=1; edge_pts=(qr_finder_edge_pt *)mymalloc(SRAMEX, nedge_pts*sizeof(*edge_pts)); centers=(qr_finder_center *)mymalloc(SRAMEX, QR_MINI(nhclusters,nvclusters)*sizeof(*centers)); ncenters=qr_finder_find_crossings(centers,edge_pts, hclusters,nhclusters,vclusters,nvclusters); *_centers=centers; *_edge_pts=edge_pts; } else ncenters=0; myfree(SRAMEX, vclusters); myfree(SRAMEX, vneighbors); myfree(SRAMEX, hclusters); myfree(SRAMEX, hneighbors); return ncenters; }

 

 

static int qr_finder_cluster_lines(qr_finder_cluster *_clusters, qr_finder_line **_neighbors,qr_finder_line *_lines,int _nlines,int _v){ unsigned char *mark; qr_finder_line **neighbors; int nneighbors; int nclusters; int i; /*TODO: Kalman filters!*/ mark = (unsigned char *)mymalloc(SRAMEX, _nlines * sizeof(*mark)); if(NULL == mark) return 1; mymemset(mark, 0, _nlines * sizeof(*mark)); neighbors=_neighbors; nclusters=0; for(i=0;i<_nlines-1;i++)if(!mark[i]){ int len; int j; nneighbors=1; neighbors[0]=_lines+i; len=_lines[i].len; for(j=i+1;j<_nlines;j++)if(!mark[j]){ const qr_finder_line *a; const qr_finder_line *b; int thresh; a=neighbors[nneighbors-1]; b=_lines+j; /*The clustering threshold is proportional to the size of the lines, since minor noise in large areas can interrupt patterns more easily at high resolutions.*/ thresh=a->len+7>>2; if(abs(a->pos[1-_v]-b->pos[1-_v])>thresh)break; if(abs(a->pos[_v]-b->pos[_v])>thresh)continue; if(abs(a->pos[_v]+a->len-b->pos[_v]-b->len)>thresh)continue; if(a->boffs>0&&b->boffs>0&& abs(a->pos[_v]-a->boffs-b->pos[_v]+b->boffs)>thresh){ continue; } if(a->eoffs>0&&b->eoffs>0&& abs(a->pos[_v]+a->len+a->eoffs-b->pos[_v]-b->len-b->eoffs)>thresh){ continue; } neighbors[nneighbors++]=_lines+j; len+=b->len; } /*We require at least three lines to form a cluster, which eliminates a large number of false positives, saving considerable decoding time. This should still be sufficient for 1-pixel codes with no noise.*/ if(nneighbors<3)continue; /*The expected number of lines crossing a finder pattern is equal to their average length. We accept the cluster if size is at least 1/3 their average length (this is a very small threshold, but was needed for some test images).*/ len=((len<<1)+nneighbors)/(nneighbors<<1); if(nneighbors*(5<<QR_FINDER_SUBPREC)>=len){ _clusters[nclusters].lines=neighbors; _clusters[nclusters].nlines=nneighbors; for(j=0;j<nneighbors;j++)mark[neighbors[j]-_lines]=1; neighbors+=nneighbors; nclusters++; } } myfree(SRAMEX, mark); return nclusters; }

 

 

struct qr_finder_cluster{ /*Pointers to the lines crossing the pattern.*/ qr_finder_line **lines; /*The number of lines in the cluster.*/ int nlines; };

 

struct qr_finder_line { /*The location of the upper/left endpoint of the line. The left/upper edge of the center section is used, since other lines must cross in this region.*/ qr_point pos; /*The length of the center section. This extends to the right/bottom of the center section, since other lines must cross in this region.*/ int len; /*The offset to the midpoint of the upper/left section (part of the outside ring), or 0 if we couldn't identify the edge of the beginning section. We use the midpoint instead of the edge because it can be located more reliably.*/ int boffs; /*The offset to the midpoint of the end section (part of the outside ring), or 0 if we couldn't identify the edge of the end section. We use the midpoint instead of the edge because it can be located more reliably.*/ int eoffs; };

 

转载于:https://www.cnblogs.com/picky-eater/p/11524190.html

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