Generating a mask from scratch

Hi

I would like to generate a simple mask image from scratch in Matlab if it is possible.

It has the following criteria:

1. the size of the image needs to be 500 x 500 pixels.
2. the center of the mask image needs to be a number, say 8. This area is white [255 255 255].
3. the size of the number is best to be adjustable by fontsize?.
4. the rest of the areas in the mask image needs to be black [0 0 0].

See the sample image below which is NOT done in Matlab. Is this achievable in Matlab?

Answer 1

[Image Analyst]

It's a trivial modification of the code in the FAQ that draws a ring. Just make two rings with different centers and radii.

https://matlab.fandom.com/wiki/FAQ#How_do_I_create_a_ring?

You could also use insertText if you have the Computer Vision Toolbox.

[Salad Box]

Thank you for your answer. I am not exactly sure whether this is what I need though.

[Image Analyst]

Well you accepted your own answer where you used my suggestion of using insertText. So why was my answer not what you needed?

And you originally posted an 8 which looked like two rings which can be created from the FAQ code if you didn't have the Computer Vision Toolbox. This would have worked for the 8.

So I feel like I gave you what you needed. Since you accepted your own answer can you at least click the "Vote" icon for mine (it awards me "reputation points")? Thanks in advance. 🙂

[Salad Box]

I accepted your answer. Thank you for your contribution. I realized that my answer is not perfect. When I double the size, the image is not pure black and white no more but with some noise. I need to fix that I think.

[Image Analyst]

Thanks. You can use imbinarize to force it to have no "noise" or gray levels, which are probably used to anti-alias (smooth) the character. Also, if you save the image(s) make sure you use the PNG extension, for lossless compression, rather than JPG which will change and add gray levels due to it being lossy compression.

[Salad Box]

Thank you very much for your advices. I will try the imbinarize.