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Restore or copy IMROI / IMFREEHAND objects?

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Matthias
Matthias on 12 Oct 2012
Answered: Tim Jackman on 27 Sep 2018
Hello!
I have a question regarding IMFREEHAND:
I need to create similar ROIs in several similar images and therefore would like to be able to save the ROI objects and reload them onto new figure objects. The ROIs must remain editable after copying because their exact position might have to be readjusted. However, whenever I close the figure in which the ROIs were created, the IMROI objects are automatically deleted.
Is there a way to achieve what I want?
With IMRECT, you can specify an initial size and position for the ROI and use this feature to save and load ROIs, but this does not seem to be possible with IMFREEHAND.
Thanks, Matthias

Accepted Answer

Image Analyst
Image Analyst on 12 Oct 2012
I believe that is not an option for imfreehand. Let's say you did have handles like imrect or impoly - they would be practically every pixel. Then what would happen if you tried to grab a handle and move it? Just one pixel would move and the rest of the outline would stay put because you didn't grab their handles. So your new outline would look like the old one with a sharp spike sticking out of it. That doesn't seem very useful.
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Matthias
Matthias on 15 Oct 2012
But how can I re-load this information and have the saved ROI be displayed in a new figure, such that it is still interactive? Saving the information works fine. I also have no trouble saving and loading information extracted from the ROI object (say, the coordinates of the boundary), but I don't know how to load the object itself and apply it to some new image such that it appears as if I had just drawn it in that image using imfreehand.

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More Answers (2)

Matthias
Matthias on 15 Oct 2012
I'm still very much interested in finding a solution for my problem.
I don't know anything about the relationship between the imroi objects and the figure they were drawn in, so I cannot tell if my question is completely impossible, or if there might be a way to make it work. If somebody knows that the former is true, let me know, that would also be helpful!
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Tim Jackman
Tim Jackman on 27 Sep 2018
The new drawfreehand ROI supports save/load. You can save the entire figure and reload it, or you can save the ROI into a mat file and reload the ROI later.
When reloading the ROI, you need to set the Parent property of the ROI to the new axes.
https://www.mathworks.com/help/images/ref/drawfreehand.html

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