How to take circular ROI

Hi, I am trying to get a circular ROI within the image. For rectangular ROI we can use imrect and get the position/coordinate, so is there a similar function to take circular ROI ?. I tried with imellipse but the coordinate that the function return I am not able to crop using imcrop. I am attaching an image here with desire ROI please let me know your suggestions. Thank you,

Answer 1

[Image Analyst]

Simply threshold

Mask = grayImage > someThresholdValue;

[D.J.]

How is this an answer?

Answer 2

[Tim Jackman]

Starting in 18b, you can use drawcircle to create a circular ROI:

https://www.mathworks.com/help/images/ref/drawcircle.html

For more information about the new suite of ROI tools, please take a look at the following link:

https://www.mathworks.com/help/images/roi-based-processing.html