Tracing one line image

Hi,

I need to trace a oneline image for a project. A one line image is an drawing/image made with just one line. Im trying to write a code that traces the line and exports this to x y coordinates, (an array). Does anyone have a clue how to do this?

Thank you!!

Answer 1

[Matt J]

One way would be to use bwconvhull.

[x1,y1, x2,y2]=deal(5,6, 13,14); %the two end points

BW=false(20);

BW(y1,x1)=1;
BW(y2,x2)=1;

BW=bwconvhull(BW);

imshow(BW)

[anouar atmn]

Im trying to trace a complicated line that forms 'art', bwconvhull would be complicated for this application right?

[Matt J]

I don't know what you mean by a complicated line. A line is a line (or rather a line segment) if and only if it is the convex hull of two points.

[anouar atmn]

This is an example of what im trying to trace

Answer 2

[Image Analyst]

I'd first call edge with 'Canny' to get your edges. Then I'd label the edges so that you draw each edge one at a time

[labeledEdges, numCurves] = bwlabel(edgeImage);

Then for each one, get the coordinates and put them in a loop to draw them

hold on; % Don't let plotting blow away image.
for k = 1 : numCurves
    thisCurve = ismember(labeledEdges, k);
    [rows, columns] = find(thisCurve);
    for k2 = 1 : length(rows)
        plot(columns(k2), rows(k2), 'r.', 'MarkerSize', 10)
        drawnow;
        pause(0.2);
    end
end
hold off;