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Proceedings Paper

Compensating for colour artefacts in the design of technical kaleidoscopes
Author(s): Šárka Němcová; Vlastimil Havran; Jiří Čáp; Jan Hošek; Jiří Bittner
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Paper Abstract

In computer graphics and related fields, bidirectional texture function (BTF) is used for realistic and predictive rendering. BTF allows for the capture of fine appearance effects such as self-shadowing, inter-reflection and subsurface scattering needed for true realism when used in rendering algorithms. The goal of current research is to get a surface representation indistinguishable from the real world. We developed, produced and tested a portable instrument for BTF acquisition based on kaleidoscopic imaging. Here we discuss the colour issues we experienced after the initial tests. We show that the same colour balance cannot be applied to the whole picture as the spectral response of the instrument varies with the position in the image. All optical elements were inspected for their contributions to the spectral behaviour of the instrument. The off-the-shelf parts were either measured or the manufacturer’s data were considered. The custom made mirrors’ spectral reflectivity was simulated. The mathematical model of the instrument was made. We found a way how to implement all these contributions to the image processing pipeline. In this way, a correct white balance for each individual pixel in the image is found and applied, allowing for a more faithful colour representation. Also proposed is an optimized dielectric protective layer for the kaleidoscope’s mirrors.

Paper Details

Date Published: 23 June 2016
PDF: 8 pages
Proc. SPIE 9896, Optics, Photonics and Digital Technologies for Imaging Applications IV, 989608 (23 June 2016); doi: 10.1117/12.2225166
Show Author Affiliations
Šárka Němcová, Czech Technical Univ. in Prague (Czech Republic)
Vlastimil Havran, Czech Technical Univ. in Prague (Czech Republic)
Jiří Čáp, Czech Technical Univ. in Prague (Czech Republic)
Jan Hošek, Czech Technical Univ. in Prague (Czech Republic)
Jiří Bittner, Czech Technical Univ. in Prague (Czech Republic)


Published in SPIE Proceedings Vol. 9896:
Optics, Photonics and Digital Technologies for Imaging Applications IV
Peter Schelkens; Touradj Ebrahimi; Gabriel Cristóbal; Frédéric Truchetet; Pasi Saarikko, Editor(s)

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