roipoly with a specified area

Hi there, I am interested in specifiying a region of interest in an image, with a specified area A. A possibility is maybe to modify the roipoly function, but I don't know how to do it quickly.

I am quite new and I don't know if in matlab there are similar functionalities...

Thanks to all

Alessio

Answer 1

[Nuno]

You can use this sintaxe:

frame(y1(1):y1(2),x1(1):x1(2),:);

With this, you specify 4 points...

[alessio]

Thank you very much for your reply Nuno, but I was interested in something more interactive, without having to specify in advance the coordinates... Like a roipoly with a forcing on the spanned area

Alessio

Answer 2

[Sean de Wolski]

How about poly2mask?

doc poly2mask

[alessio]

Thank you Sean de, I tried with poly2mask but what I need is an interactive way to specify the roi like polyroi, that at the same time force the area to a fixed value... I'm not sure if it is possible without rewriting some code...

Alessio

[Sean de Wolski]

Well, yes you'll probably have to write some code. But you can easily and quickly generate masks of a non-convex area with poly2mask, and then sum it or use bwarea to get its area, and then dilate it or erode it automatically if too big or too small.