Illuminant Spectra-based Source Separation Using Flash Photography
This addresses the challenge of illuminant separation in photography for post-processing applications, offering an automated solution that improves on existing methods.
The paper tackles the problem of separating multiple illuminants in a scene using flash/no-flash image pairs, deriving a physics-based method to automatically separate images into constituent illuminants for applications like white balancing and lighting editing, with results outperforming state-of-the-art techniques.
Real-world lighting often consists of multiple illuminants with different spectra. Separating and manipulating these illuminants in post-process is a challenging problem that requires either significant manual input or calibrated scene geometry and lighting. In this work, we leverage a flash/no-flash image pair to analyze and edit scene illuminants based on their spectral differences. We derive a novel physics-based relationship between color variations in the observed flash/no-flash intensities and the spectra and surface shading corresponding to individual scene illuminants. Our technique uses this constraint to automatically separate an image into constituent images lit by each illuminant. This separation can be used to support applications like white balancing, lighting editing, and RGB photometric stereo, where we demonstrate results that outperform state-of-the-art techniques on a wide range of images.