MATLAB: How to convert a closed curve into a binary mask

Question

I have a set of 2D closed curves represented by their X and Y ordered coordinates in a text file.

I have attached one of the curves as an example.

My goal is to convert the enclosed area into a binary image.

Builtin dunction "poly2mask" generates a completely black square whereas I would like the region inside the closed curve to be black

and the region outside the curve to be white.

Thank you in advance for any suggestion and help.

Regards,

Maura

Answer 1

data = importdata('data.txt') ; 
x = data(:,1) ; 
y = data(:,2) ; 
N = 500 ; 
xi = linspace(min(x),max(x),N) ; 
yi = linspace(min(y),max(y),N) ; 
[X,Y] = meshgrid(xi,yi) ; 
idx = inpolygon(X,Y,x,y) ; 
Z = ones(size(X)) ; 
Z(idx) = 0 ; 
imshow(Z)