How to draw a disk of given center and radius ?

I have computed the center and radius and now I want to draw a white disk using these parameters on a black background. I tried something like below but its generating a flat edge in four directions. It is kind of urgent to compare the results so any help would be appreciated. I have attached two images to keep my point. Please zoom the images in order to see what am I claiming.

    [imageSizeY,imageSizeX,d] = size(imgimg);
    [columnsInImage, rowsInImage] = meshgrid(1:imageSizeX, 1:imageSizeY);
    centerX = floor(centroid(1));
    centerY = floor(centroid(2));
    radius = ceil(radii);
    circlePixels = (rowsInImage - centerY).^2 + (columnsInImage - centerX).^2 <= radius.^2;
    circlePixels = mat2gray(circlePixels);
    %figure, imshow(circlePixels);
    formatSpec_org = 'Proposed%d.png';
    strProposed1 = sprintf(formatSpec_org, x);
    strProposed2 = 'OutputFolder\';
    s_P = strcat(strProposed2,strProposed1);
    imwrite(circlePixels,s_P)

Answer 1

[Image Analyst]

Those are simply quantization/digitization errors. If you want a smoother circle, you need to have more pixels in your image. A finer resolution will give you smoother edges on your circle with smaller flat edges along the horizontal and vertical sides.

[Gunjan Gautam]

Thanks for the prompt response. I would be grateful if you could be more specific. Can I control having more pixels as it is generated by MATLAB code? Ultimately, I want a smoother disk because it is jeopardizing my results.

[Image Analyst]

I don't know what imgimg is. Why don't you try making it bigger, like

imgimg = imresize(imgimg, 3); % Increase by a factor of 3.

Then follow with the rest of your code, making adjustments to the center and radius as needed.

Answer 2

[shamookh alqahtani]

[imageSizeY,imageSizeX,d] = size(imgimg);

[columnsInImage, rowsInImage] = meshgrid(1:imageSizeX, 1:imageSizeY);

centerX = floor(centroid(1));

centerY = floor(centroid(2));

radius = ceil(radii);

circlePixels = (rowsInImage - centerY).^2 + (columnsInImage - centerX).^2 <= radius.^2;

circlePixels = mat2gray(circlePixels);

%figure, imshow(circlePixels);

formatSpec_org = 'Proposed%d.png';

strProposed1 = sprintf(formatSpec_org, x);

strProposed2 = 'OutputFolder\';

s_P = strcat(strProposed2,strProposed1);

imwrite(circlePixels,s_P)

[Image Analyst]

How is this different than the original code the poster posted? What did you change?