Separation of irradiance and reflectance from observed color images by logarithmical nonlinear diffusion process

Takahiro Saito; Hiromi Takahashi; Takashi Komatsu

doi:10.1117/12.641329

2 February 2006 Separation of irradiance and reflectance from observed color images by logarithmical nonlinear diffusion process

Takahiro Saito, Hiromi Takahashi, Takashi Komatsu

Author Affiliations +

Proceedings Volume 6065, Computational Imaging IV; 606511 (2006) https://doi.org/10.1117/12.641329
Event: Electronic Imaging 2006, 2006, San Jose, California, United States

Abstract

The Retinex theory was first proposed by Land, and deals with separation of irradiance from reflectance in an observed image. The separation problem is an ill-posed problem. Land and others proposed various Retinex separation algorithms. Recently, Kimmel and others proposed a variational framework that unifies the previous Retinex algorithms such as the Poisson-equation-type Retinex algorithms developed by Horn and others, and presented a Retinex separation algorithm with the time-evolution of a linear diffusion process. However, the Kimmel's separation algorithm cannot achieve physically rational separation, if true irradiance varies among color channels. To cope with this problem, we introduce a nonlinear diffusion process into the time-evolution. Moreover, as to its extension to color images, we present two approaches to treat color channels: the independent approach to treat each color channel separately and the collective approach to treat all color channels collectively. The latter approach outperforms the former. Furthermore, we apply our separation algorithm to a high quality chroma key in which before combining a foreground frame and a background frame into an output image a color of each pixel in the foreground frame are spatially adaptively corrected through transformation of the separated irradiance. Experiments demonstrate superiority of our separation algorithm over the Kimmel's separation algorithm.

Citation Download Citation

Takahiro Saito, Hiromi Takahashi, and Takashi Komatsu "Separation of irradiance and reflectance from observed color images by logarithmical nonlinear diffusion process", Proc. SPIE 6065, Computational Imaging IV, 606511 (2 February 2006); https://doi.org/10.1117/12.641329

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