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Recognition of facial expressions - Knowledge Based Systems ...

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Equation 20<br />

The value <strong>of</strong> the angle is then used for correcting the whole image by rotating it with the<br />

computed angle. Following the rotation procedure, the symmetric <strong>facial</strong> points are<br />

horizontally aligned. The point used as image rotation center is computed to be on the<br />

segment at the half distance between the eyes. The distance between the eyes represents<br />

the new parameter, base , whose value is computed using Equation 21.<br />

The rotation point has the coordinates .<br />

Equation 21<br />

The parameter base is further used to adjust all the distance parameters between any<br />

FCPs for making the recognition process robust to the distance to the camera, and also<br />

person-independent.<br />

Given the value <strong>of</strong> α , all the pixels are rotated on the screen by using Equation 22.<br />

Equation 22<br />

- 64 -

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