FHROI: Interactive freehand ROI

Interactively specify 2D freehand ROI

Description

FHROI: Interactively specify 2D freehand ROI

Overlays an imfreehand ROI on an image.
Gives the ability to tweak the ROI by adding and
  subtracting regions as needed, while updating
  the ROI boundaries as an overlay on the image.
Returns a logical matrix of the same size as the
  overlain image.

Requires alphamask:
  http://www.mathworks.com/matlabcentral/fileexchange/34936

Usage:
  bwMask = fhroi([axHandle])
    axHandle: handle to axes on which to operate (optional)
      bwMask: ROI mask as logical matrix

Example:
  figure;
  I = rand(20) + eye(20);
  imshow(I, [], 'Colormap', hot, 'initialMagnification', 1000);
  bwMask = fhroi;

See also IMFREEHAND, CREATEMASK

• Required Products: Image Processing Toolbox
• MATLAB release: MATLAB 7.12 (R2011a)

[Andrew Davis]

I thought I would post this question I received via email in case others have a similar question:

Q: I was wondering if there is a modification that can be made to report the roi (bwMask) not as a binary, but with the original signal intensities of the image?

A: The nice thing about returning the ROI as a logical is that it can be used to index the original matrix directly. So if your original image was I, you can call
>> Iselected = I(bwMask);
to get a vector of signal intensities corresponding to the ROI. Or to get an image with the non-ROI pixels zeroed out, you could call
>> Imasked = I.*bwMask;

For more, see Steve's blog: http://blogs.mathworks.com/steve/2008/01/28/logical-indexing/

[Lili]