Global Thresholding

Goal: To segment an object from the background using thresholding.

I implemented the following algorithm in matlab. (See Example 10.10) Guess the threshold. Segment

the image using that threshold. Compute the average intensity of each threshold image. Set T=1/2*(avg1+avg2).

Repeat segmentation and averaging until T converges. In the example below, I took the average (107.5) of the

image intensities for the initial guess because the object takes up a considerable portion of the image space. The

algorithm completed in 3 iterations (with T=127.0). For this example, it did an excellent job; although, this does

not appear to be a very difficult image to segment.

A) Original image.

B) Segmented image.

matlab code