Edge detection result should be enhanced using linear method like Median filter to

remove the garbage around the pupil to gain clear pupil to determine perfect centre. Get the

centre of the pupil by counting the number of black pixels (zero value) of each column and

row. Then get each row and column that has the maximum number of these black pixels.

Then determine the center by simple calculation according to the image coordinate to set it

correct on the image, consequently we can determine the radius of the pupil. Thus we can find

the pupillary boundary (inner). A similar procedure is extended by using a coarse scale to

locate the outer boundary (limbus) which can be apparent by using the mid-point algorithms

of circle and ellipse.