Create an ROI based on matrix values

Hi all,

Trying to figure out how to auto-create an ROI (region or interest) based on values in a matrix. For that matter, the matrix has binary values, 0 or 1. If the cell has '1', than I it's inside an ROI, '0' is out. So as a result, I would have for that matrix - ROI's that bound the areas where '1' is the value.

Thanks, Dor

Answer 1

[Walter Roberson]

That matrix is already the ROI.

Potentially you might want to do something like

ROI = imfill(YourMatrix, 'holes');

if you want to convert things like

    0 0 0 0 0
    0 1 1 1 0
    0 1 0 1 0
    0 1 1 1 0
    0 0 0 0 0

to

    0 0 0 0 0
    0 1 1 1 0
    0 1 1 1 0
    0 1 1 1 0
    0 0 0 0 0

If for some reason you only want the coordinates of the outside boundary (which is not how you typically use ROIs) then https://www.mathworks.com/help/images/ref/bwboundaries.html or https://www.mathworks.com/help/images/ref/bwtraceboundary.html

If you want the smallest enclosing rectangle around the area that has 1's (which is often used with ROIs), then use regionprops() with the 'boundingbox' option.