CODEWITHSUNDEEP
c++cimage-processingopencv
Gambit King
Gambit King

Reputation: 483

Tracing Connected Pixels

I want to trace all the connected pixels of an image. I used the canny algorithm for edge detection and now need to get each unique shape.

enter image description here here is my code for the following 

x_axis = marker_i;   // x & y co-ordinates of the first detected pixels
y_axis = marker_j;

do
{

for (int i=0;i<8;i++){

if(i==0){x_axis = x_axis-1;  y_axis = y_axis-1;}  // each iteration checks one 
if(i==1){x_axis = x_axis;    y_axis = y_axis+1;}  // of the 8 adjacent pixels 
if(i==2){x_axis = x_axis;    y_axis = y_axis+1;}  // for a match 
if(i==3){x_axis = x_axis+1;  y_axis = y_axis-2;}
if(i==4){x_axis = x_axis;    y_axis = y_axis+2;}
if(i==5){x_axis = x_axis+1;  y_axis = y_axis-2;}
if(i==6){x_axis = x_axis;    y_axis = y_axis+1;}
if(i==7){x_axis = x_axis;    y_axis = y_axis+1;}

if(x_axis >= 1024 || y_axis >= 1280){ x_axis = 0; y_axis = 0;}

if(ch_rd == red [x_axis][y_axis] && ch_gr == green[x_axis][y_axis] 
&& ch_bl == blue[x_axis][y_axis] && pixel_comp[x_axis][y_axis]==0){ 

map++;
pixel_comp[x_axis][y_axis] = 2;                  // marks that pixel as read
pixal[num][0]    = x_axis;
pixal[num][1]    = y_axis;

if (map == 1){ curs[0] = x_axis; curs[1] = y_axis;}
if (map >  1){ div[est] = num; est++;}   // if there is more than one detection
num++;                                   // adds remaining to an array div

}

}

if(map==0){ 
x_axis = pixal[div[prev]][0]; y_axis = pixal[div[prev]][1]; prev++; 
    // if nothing is detected goes to the last item from array div
}
else{ 
x_axis = curs[0]; y_axis = curs[1]; 
} 
if(map==0 && prev>=est){ dead_end = 1;}
map = 0;
}
while (dead_end==0);

I was using this on a previous version of my program and it would unfortuantely detect all shapes even if they were not connected instead of one by one, now i've been trying opencv and was wondering if there was a function or implementation which does this or even an non-opencv implementation or example that i could use ? What is a simple algorithm for this purpose ?

Upvotes: 1

Views: 1073

Answers (1)

peter.murray.rust
peter.murray.rust

Reputation: 38043

A good place to start is the Wikipedia article on Flood Fill . This has animations of the filling algorithm.

[You didn't ask for corrections to your program.]

Upvotes: 1

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