To evaluate and optimally design spectral sensitivity functions for color input devices, a metric that incorporates practical, significant requirements is desired. The candidate metrics are Vora–Trussell's μ-factor, a metric based on geometrical difference, and the proposed Unified Measure of Goodness, or UMG, which simultaneously considers the imaging noise and its propagation, colorimetric reproduction accuracy and multi-illuminant color correction. A systematic approach is presented to searching for an optimal set of spectral sensitivity functions from among the complete combinations of the given filter components. Comparative computation results show that μ-factor is not a competent metric for the optimal design of camera spectral sensitivity functions while UMG is able to pick out the optimum successfully. Furthermore, the ultimate optimal set has been obtained by selecting the set with highest μ-factor value from the sub-optimal collection obtained with UMG. This hierarchical approach comprehensively considers the advantages of both quality metrics. The candidates of the optimal sets based on the given filter components are experimentally tested and presented in the end of the article.