doc inpolygon
N = 30 ;
[X,Y] = meshgrid(1:N,1:N) ;
plot(X,Y,'.k','markersize',10) ;
%%polygon coordinates
Rect = [ 8.5369 23.4840
17.4539 23.4840
17.5230 16.7493
7.6382 16.4869
8.5369 23.4840] ;
hold on
plot(Rect(:,1),Rect(:,2),'r');
%%get points inside the polygon
idx = inpolygon(X,Y,Rect(:,1),Rect(:,2)) ;
%%points inside polygon
xi = X(idx) ; yi = Y(idx) ;
plot(xi,yi,'ob')