Designing a physically-feasible colour filter to make a camera more colorimetric

TL;DR

This paper extends Luther-condition based camera filter optimization to include practical constraints like smoothness and transmittance, resulting in physically feasible filters that improve camera colorimetry.

Contribution

It introduces a method to design physically realizable colour filters that are smooth and transmissive, enhancing camera colorimetric performance while considering fabrication constraints.

Findings

Filters are more smooth and transmissive

Enhanced colorimetric accuracy of the camera

Practical feasibility of filter fabrication

Abstract

Previously, a method has been developed to find the best colour filter for a given camera which results in the new effective camera sensitivities that best meet the Luther condition. That is, the new sensitivities are approximately linearly related to the XYZ colour matching functions. However, with no constraint, the filter derived from this Luther-condition based optimisation can be rather non-smooth and transmit very little light which are impractical for fabrication. In this paper, we extend the Luther-condition filter optimisation method to allow us to incorporate both the smoothness and transmittance bounds of the recovered filter which are key practical concerns. Experiments demonstrate that we can find physically realisable filters which are smooth and reasonably transmissive with which the effective "camera+filter" becomes significantly more colorimetric.