Thomson Licensing

Matis Hudon

Philippe Robert

Paul Kerbiriou

Olivier Bureller

Salma Jiddi

A method, apparatus and system for estimating reflectance parameters and a position of the light source(s) of specular reflections of a scene include RGB sequence analysis with measured geometry in order to estimate specular reflectance parameters of an observed 3D scene. Embodiments include pixel-based image registration from which profiles of 3D scene points image intensities over the sequence are estimated. A profile is attached to a 3D point and to the set of pixels that display its intensity in the registered sequence. Subsequently, distinction is made between variable profiles that reveal specular effects and constant profiles that show diffuse reflections only. Then, for each variable profile diffuse reflectance is estimated and subtracted from the intensity profile to deduce the specular profile and the specular parameters are estimated for each observed 3D point. Then, the location of at least one light source responsible for the specular effects is estimated. Optionally, the parameters can be iteratively refined to determine color information and specular reflectance parameters.

Method and apparatus for estimating reflectance parameters and a position of a light source in a scene

An electronic imaging device having a plurality of photosensitive cells arranged in an array to form a frame region, the frame region being composed of a plurality of frame sub-regions each frame sub-region corresponding to a sub-set of photosensitive cells, the device comprising an array controller configured to expose each of said frame sub-regions during an exposure duration wherein the exposure of at least some of said frame sub-regions occurs at different times during a total time of exposure of the frame region, a flash unit for illuminating a scene to be imaged during a flash time duration an activator for activating the flash unit to illuminate the scene to be imaged at a flash time delay determined in dependence upon said exposure duration of a frame sub region and the flash time duration; an image data acquisition unit for acquiring a set of frames of the scene wherein the time of occurrence of a flash event within a frame shifts temporally from frame to frame; and an image reconstruction unit for constructing a sequence of images from the frame sub-regions of the acquired frames.

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Rennes, France

Matis Hudon