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Turning a Digital Camera into an Absolute 2D Tele‐Colorimeter
Author(s) -
Guarnera G. C.,
Bianco S.,
Schettini R.
Publication year - 2019
Publication title -
computer graphics forum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 120
eISSN - 1467-8659
pISSN - 0167-7055
DOI - 10.1111/cgf.13393
Subject(s) - colorimeter , chromaticity , computer science , computer vision , rgb color model , artificial intelligence , radiance , rendering (computer graphics) , hue , spectral power distribution , high dynamic range , color rendering index , luminance , computer graphics (images) , upsampling , optics , dynamic range , physics , image (mathematics) , light emitting diode
We present a simple and effective technique for absolute colorimetric camera characterization, invariant to changes in exposure/aperture and scene irradiance, suitable in a wide range of applications including image‐based reflectance measurements, spectral pre‐filtering and spectral upsampling for rendering, to improve colour accuracy in high dynamic range imaging. Our method requires a limited number of acquisitions, an off‐the‐shelf target and a commonly available projector, used as a controllable light source, other than the reflected radiance to be known. The characterized camera can be effectively used as a 2D tele‐colorimeter, providing the user with an accurate estimate of the distribution of luminance and chromaticity in a scene, without requiring explicit knowledge of the incident lighting power spectra. We validate the approach by comparing our estimated absolute tristimulus values (XYZ data in c d /m 2 ) with the measurements of a professional 2D tele‐colorimeter, for a set of scenes with complex geometry, spatially varying reflectance and light sources with very different spectral power distribution.