Ethnographic Analysis Essay

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Chapter 2
Segmentation
2.1 OVERVIEW
The eye conatins two concentric cirles , the iris/sclera boundary and the iris/pupil boundary. The objective is to isolate the actual iris region from the rest of the image. The image may contan some
Noise and the same could be occuluded due to eye lashes and eyelids. So in this step we have to excude these interfrences corrupting the image and determine the circular iris region. The results may depend upon the quality of the image. The database used can have pecuilaiar corruptions for ex the LEI database contains specular reflections in all images and CASIA does not have it. This stage is very critical as any false representation of data at this stage will have cascading effect on the compete databse templates …show more content…

The same is fixed by roatting the image in a fixed direction and align both the templates at matching stage.
3.2 Implementation
Daugman’s rubber sheet model technique was adopted for normalization. Reference point is the centre of the pupil and radial vectors are assumed to pass from centre till the iris boundary. A number of feature points are selected on these vectors. The number of points on the radial line is called radial resolution and along the angular line is called angular resolution.
A remapping function is used to rescale the points on the angular lines. A fixed number of points is taken on each radial vector. The Cartesian coordinates form the normalized pattern are back tracked to get the radial and angular positions. The size of the rubber sheet was taken as 10 pixels on the radial vector and 40 on the angular vector.
3.3 Result
The Daugman’s rubber sheet model was successfully implemented and images normalized. However the process was not able to reconstruct the exact pattern in varying dilation levels of the pupil. The relational consistencies were not addressed at this stage, so various normalized samples looked misaligned. The issue is addressed in the matching

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