Autoselection of ROI within a selected area

[Maj Kj=?ISO-8859-1?Q?=C3=A6rgaard?=]

Hello

I use an ImageJ plugin named "PFRET" developed by Dr.Periasamy in
Virginia. In this plugin you an option of autoselction of ROI of a
specified size and intensity. However, the plugin selectes ROI over the
entire image and I would like only to select ROIs in a region I specify.
Is there a plugin or a way of developing a plugin where the ROIs is only
selected in a part of the image which you define yourself.

Thank you