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Accurate estimation of the nonlinearity of input/output response for color cameras
Author(s) -
Cheung Vien,
Westland Stephen,
Thomson Mitch
Publication year - 2004
Publication title -
color research and application
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 62
eISSN - 1520-6378
pISSN - 0361-2317
DOI - 10.1002/col.20061
Subject(s) - smoothness , nonlinear system , luminance , linearization , computer science , characterization (materials science) , gamma correction , process (computing) , power (physics) , computer vision , artificial intelligence , algorithm , mathematics , optics , image (mathematics) , physics , mathematical analysis , quantum mechanics , operating system
This study investigates techniques for accounting for the nonlinearity of the input/output response of a camera system. A simple power‐law form of the nonlinearity was assumed and estimates of the value for the exponent for each of the color channels were made using three different methods. The responses from an Agfa StudioCam camera were linearized and then device characterization was attempted. Characterization errors were up to 10% better using the spectral‐sensitivities‐based method for estimating the nature of the nonlinearity than using the other two methods. We therefore suggest that the spectral‐sensitivities‐based method should be preferred for characterization or any other computational process that requires linearization of the camera responses. We expect greater benefits using this method for “low‐end” camera systems and/or for cameras where the spectral sensitivities are known or more precisely estimated. We also expect the smoothness of the illumination to influence the error in the estimates of the nonlinearity using the luminance‐ and mean‐reflectance‐based methods. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 406–412, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20061