I am trying to find the function of the contour line of a grayscale image, but I can't seem to get it to work, anybody know what im doing wrong?

So basically I have a grayscale image, which has been blurred to smooth out the intensities in the image. What I need to do is get the function of the contour line for the grayscale image for an intensity of 60. I think contourc is supposed to help me get the points, however I either don't understand it properly, or am doing something wrong. My grayscale image is "gray".

My code is essentially this:

d=contourc(gray,[60 60]);

I thought this would return a two row matrix of all the points/pixels of the contour line. However i get an error "Error using contourc Input arguments for contourc must be of type 'double'."

Anybody know what I am doing wrong? Have I completely misunderstood the use of this function?

Answer 1

[Star Strider]

Try this:

d=contourc(double(gray),[60 60]);