Turning a Digital Camera into an Absolute 2D Tele‐Colorimeter

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 r...

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Bibliographic Details
Published in:Computer graphics forum Vol. 38; no. 1; pp. 73 - 86
Main Authors: Guarnera, G. C., Bianco, S., Schettini, R.
Format: Journal Article
Language:English
Published: Oxford Blackwell Publishing Ltd 01.02.2019
Subjects:
Apertures
appearance modelling
Chromaticity
Colorimetry
colour
Computer graphics
Digital cameras
Electric power distribution
Explicit knowledge
I.3.3 [Computer Graphics]: Picture/Image Generation—I.4.1 [Image Processing and Computer Vision]: Digitization and Image Capture—I.4.8 [Image Processing and Computer Vision]: Scene Analysis
image and video processing
image‐based rendering
Irradiance
Light sources
Luminance distribution
modelling
Power spectra
Radiance
Reflectance
rendering
ISSN:0167-7055, 1467-8659
Online Access:Get full text
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Summary: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 cd/m2) 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. 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.
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content type line 14
ISSN:0167-7055
1467-8659
DOI:10.1111/cgf.13393