Mulit-Resolution Aitchison Geometry Image Denoising for Low-Light Photography

Date of Award


Degree Name

M.S. in Electrical Engineering


Department of Electrical and Computer Engineering


Advisor: Keigo Hirakawa


In low-photon imaging regime, noise in image sensors are dominated by shot noise, bestmodeled statistically as Poisson. In this work, we show that the Poisson likelihood functionis very well matched with the Bayesian estimation of the "difference of log of contrast of pixelintensities". More specifically, our work takes root in statistical compositional data analysis,whereby we reinterpret the Aitchison geometry as a multiresolution analysis in log-pixeldomain. We demonstrate that the difference-log-contrast has wavelet-like properties thatcorrespond well with human visual system, while being robust to illumination variations.We derive a denoising technique based on an approximate conjugate prior for the latentAitchison variable that gives rise to an explicit minimum mean squared error estimation.The resulting denoising techniques preserves image contrast details that are arguably moremeaningful to human vision than the pixel intensity values themselves.


Electrical Engineering, Image denoising, Poisson, low light imaging, Aitchison geometry

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