how can I create a circle band imaged from the 3 dots imaged?

how can I create a circle band imaged from the 3 dots imaged?

Answer 1

[Image Analyst]

Not sure what you mean. Do you want a circle that bounds the 3 blobs? If so, do you want to bound the whole spot, or just the centroids? Please elaborate.

Basically, find the spots using thresholding,

mask = grayImage > someThresholdValue;

then find either

1. the centroids with regionprops(mask, 'Centroid') or
2. the farthest point from the center of the 3 spots using regionprops(mask, 'Centroid', 'PixelList')

Then use code from the FAQ

https://matlab.fandom.com/wiki/FAQ#How_can_I_fit_a_circle_to_a_set_of_XY_data.3F

to fit a circle through the 3 points. Then you can use viscircles() to put the circle into the overlay above the gray scale image.

[Naomi Penelope]

I want to create a band for each of the circles.

[Image Analyst]

Simply threshold a range of values. See my interactive thresholding app:

https://www.mathworks.com/matlabcentral/fileexchange/29372-thresholding-an-image?s_tid=srchtitle

To get only 3 blobs, you can get the 3 largest blobs like this:

% Interactively threshold the gray scale image using Image Analyst's function.
[lowThreshold, highThreshold] = threshold(lowThreshold, highThreshold, grayImage);
% Create binary image mask from the thresholds.
mask = grayImage >= lowThreshold & grayImage <= highThreshold;
% Extract 3 largest blobs which will be the rings.
mask = bwareafilt(mask, 3);