Matched Illumination
This work addresses color accuracy in imaging systems, offering a practical alternative to physical filters, though it builds incrementally on prior theoretical principles.
The paper tackled the problem of improving color measurement accuracy in cameras by proposing a novel method that modulates the light source spectrum instead of using physical color filters, reducing color measurement errors by about 50% on simulated data and 25% on real images.
In previous work, it was shown that a camera can theoretically be made more colorimetric - its RGBs become more linearly related to XYZ tristimuli - by placing a specially designed color filter in the optical path. While the prior art demonstrated the principle, the optimal color-correction filters were not actually manufactured. In this paper, we provide a novel way of creating the color filtering effect without making a physical filter: we modulate the spectrum of the light source by using a spectrally tunable lighting system to recast the prefiltering effect from a lighting perspective. According to our method, if we wish to measure color under a D65 light, we relight the scene with a modulated D65 spectrum where the light modulation mimics the effect of color prefiltering in the prior art. We call our optimally modulated light, the matched illumination. In the experiments, using synthetic and real measurements, we show that color measurement errors can be reduced by about 50% or more on simulated data and 25% or more on real images when the matched illumination is used.