create freehand region of interest

I have a matlab program which I would like to be able to draw a free hand ROI on the loaded image, If I dropped off the software could someone introduce this. Currently we can only draw a square or rectangle

Answer 1

[Bjorn Gustavsson]

Have a look at ginput (there are a couple of improved/modified versions on the file exchange), that function should give you the tool to chose arbitrary polygons for your area. After that I'd use inpolygon to determine what pixels are inside the ROI. Something like this:

imagesc(im)
[xPerim,yPerim,Bperim] = ginput;
idx1 = 1:size(im,1);
idx2 = 1:size(im,2);
[idx2,idx1] = meshgrid(idx2,idx1);
inROI = inpolygon(idx2,idx1,xPerim(:),yPerim(:));

HTH