Linear combinations of metrics for assessing biometric sample quality are weak, because they lack veto power. For example, a good score for a sharp focus of an ocular image would `compensate' in an additive combination for the fact that the eyelids are fully closed; or fully open eyelids would compensate for the image being many diopters out-of-focus. Normalised multiplicative quality factors are better because they are punitive, and thereby confer veto powers. This chapter explains the basis for the product of power functions which underlie the ISO/IEC 29794-6 Iris Image Sample Quality Standard, in particular how the exponents of the power functions allow importance tailoring of each element.
Iris image quality metrics with veto power and nonlinear importance tailoring, Page 1 of 2
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