Peak finding for Canny

Also called Non-maximaSuppression

Actual code for Peaks• for(i=MR;i<256-MR;i++){• for(j=MR;j<256-MR;j++){•

• if((xconv[i][j]) == 0.0) {• xconv[i][j] = .00001;• }• slope = yconv[i][j]/xconv[i][j];• if( (slope <= .4142)&&(slope > -.4142)){• if((mag[i][j] > mag[i][j-1])&&(mag[i][j] > mag[i][j+1])){• cand[i][j] = 255;• }• }• else if( (slope <= 2.4142)&&(slope > .4142)){• if((mag[i][j] > mag[i-1][j-1])&&(mag[i][j] > mag[i+1][j+1])){• cand[i][j] = 255;• }• }• else if( (slope <= -.4142)&&(slope > -2.4142)){• if((mag[i][j] > mag[i+1][j-1])&&(mag[i][j] > mag[i-1][j+1])){• cand[i][j] = 255;• }• }else{• if((mag[i][j] > mag[i-1][j])&&(mag[i][j] > mag[i+1][j])){• cand[i][j] = 255;• }• }• }• }

Hysteresis (Double) Threshold• while(more){• more = 0;• for(i=0;i<256;i++){• for(j=0;j<256;j++){• if(cand[i][j] == 255){• if(mag[i][j] > HI){• final[i][j] = 255;• more = 1;• cand[i][j] = 0;• }• else if(mag[i][j] < LO){• final[i][j] = 0;• cand[i][j] = 0;• }• else if( (mag[i][j] > LO)&&(mag[i][j] < HI) ){• for(p=-1;p<2;p++){• for(q=-1;q<2;q++){• if(final[i+p][j+q] == 255){• final[i][j] = 255;• cand[i][j] = 0;• more = 1;• }• }• }• }/*end-last-else-if*/• }/*end-first-if*/• }• }/*end-first-for*/• }/*end-while*/•