How to convert arc circle plot into binary circle?

how to change the circumference into binary circle ?

Answer 1

[KSSV]

R = 1; 
th = linspace(0,2*pi,1000) ; 
x = R*cos(th) ; y = R*sin(th) ; 

xi = linspace(-2,2,100) ; 
yi = linspace(-2,2,100) ; 
[X,Y] = meshgrid(xi,yi) ;
Z = zeros(100) ; 
idx = knnsearch([X(:) Y(:)],[x' y']) ; 
Z(idx) = 1 ; 
imagesc(Z)

[afiq rauf]

thank you, and may i know how can i remove the arc that i have shown in the first picture?

[KSSV]

Remove the arc?

[Walter Roberson]

Change

th = linspace(0,2*pi,1000) ; 

to only have the range of angles that you want the arc to cover.

Answer 2

[Walter Roberson]

https://matlab.fandom.com/wiki/FAQ#How_do_I_create_an_arc.3F shows how to create an arc.

But for your purpose, instead of using plot(), multiply the coordinates by the resolution you want, and round() them, and then subtract off the minimum x and y . Now you have matrix coordinates.

resolution = 25;

th = linspace(0, 7*pi/9, 500);
r = 5;
xc = 3;
yc = 7;
[x,y] = pol2cart(th, r);
x = x + xc;
y = y + yc;

%the above are data coordinates. Make them into array coordinates.

buffer = 5;
xm = round(x * resolution);
ym = round(y * resolution);
xmin = min(xm);
ymin = min(ym);
xmax = max(xm);
ymax = max(ym);
xmc = xm - xmin + 1 + buffer;
ymc = ym - ymin + 1 + buffer;

arc_image = accumarray([ymc(:), xmc(:)], 1);

imshow(arc_image)