Marking the points by gpts on an image

I have to find the perimeter and area of an irregular objects using a GUI when reading the image. I have read the image in the GUI and then i have to select two reference points and a reference points from the keyboard i have done that already in the GUI using the ginput function where i have used two reference points. The figure can be downloaded from http://speedy.sh/zhAVF/irregularImage.JPG

Problem iam having is that i have to select the points on the irregular object using mouse which i will do through gpts command but i also have to outline those points on the figure, i am confused of how i will outline those points on the figure. Can you please help with that.

[Jerry]

image can be downloaded from http://www29.speedyshare.com/zhAVF/download/irregularImage.JPG