# How can I plot the detected parabola on the image?

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Alaa on 12 Jun 2015
Commented: Image Analyst on 12 Jun 2015
Hello
I've tried to detect the parabola form of the Eyelid from the normalized iris image using Hough Transform as it is coded in the following file exchange: http://www.mathworks.com/matlabcentral/fileexchange/15841-parabola-detection-using-hough-transform/content/oughparabola.m
Put I don't know how can I use the output of this code to draw the fitted parabola on the normalized iris image. The normalized iris image and it's edge image are attached

#### 1 Comment

Alaa on 12 Jun 2015
My Question is how can I use the output parameters [phi,p] in drawing the parabola???

Image Analyst on 12 Jun 2015
If you have the x,y coordinates, just put hold on and call plot:
hold on;
plot(x, y, 'b-', 'LineWidth', 2);

Alaa on 12 Jun 2015
Dear Image analysis Thank you for you answer, I knew that put my question is how the output parameters will be used the function gives me [phi,p] how can I use them in the plotting the parabola?? In other words, I get the coordinates of edge image using find function and I fed them to the HT function, and it gives me two matrix of phi and p. how can I use them in plotting the parabola??
Image Analyst on 12 Jun 2015
I don't know that program. Why don't you just get each segment, and call the built-in polyfit on it? then look at the residuals and figure that the curve with the lowest residuals is the best fit and is the curve for the upper eyelid that you want and plot that with plot(x,y). It seems simpler to me.