Create a new selection around current freehand selection

Hi all,

Apologies if I have missed any similar existing topics or made any errors, I’m new to the forum and to ImageJ!

I’m looking for a method to create an area of a given radius or diameter around a pre-existing freehand selection. For context, I am looking at a photo of a bird on a nest and I have used the freehand selection tool to outline the adult bird. I am looking to then be able to create an area of perhaps 400pixels in diameter around that current selection (not just a circle, it would be relative to the freehand selection).

If anyone has any advice or suggestions it would be greatly appreciated!

Many thanks,

Henry

Hi Henry,

Select your ROI from the Manager,
Go to Edit>Selection>Enlarge and enter the number of pixels
You now have a new ROI that is larger than your freehand selection.

M.

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Hi
@hrichardson

Another possibility to combine with that of @MatthieuV

Use your freeline Tool and draw your selection.
Edit —> Selection ----> Add to Manager
go to “window roiManager”
More —> Specify —> Oval or square
Greetings

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Thank you both for the tips!

Hi @MatthieuV ,

This seems to work perfectly, and I have now created a second ROI using the enlarge tool allowing me to have both ROIs saved. I do have one further question however - how would I go about measuring this new ROI with the original selection excluded, for example, measuring the RGB values?

Many thanks

Henry

Hi Henry,

You select the old ROI and the enlarged one in the ROI manager
In ROI Manager, go to More>> and select XOR, this excludes the inside ROI
Create a new ROI (ctrl+T)
Go to Image>Color>split channels, select individual images, select the new ROI and measure

M.

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Thank you for all the help!