Detecting Specular Reflections Using Lambertian Constraints

Specularities-briglit image regions formed by specular reflectioir-are likely to be mistalien for genuine surface ma,rking.j by processes that perform photometric analysis, derive motion fields from optical flow or estimate depth from binocular stereo. In addit8iori they can be uscd to infer surface geometry. This paper describes a scheme for detecting specularities based 011 a cliaracterisatioil of Larnbertian surfaces. Real surfaces are not simple composites of Lambertiaii and specular sur- faces hut evidence suggests that away from specrilnrities they do not deviate from the Lainbertian model by more than a factor of 3 or so. This proves adequate to serve as a constraint for specularity detection. Two independent tests identify iinage regions where tlie constraint is violated. Tlie detector is shown to performs well on a varicty of real images. Applications: improving binocular stereo and inferring surface geometry are described using specularities produced by the detector. ACI(NOWLEI)GEI\IENTS: Work done at:L)ept. Conip. Sci, TJniv. Edin- burgh; Studenthip: (gjh) IDM UKSC & SERC; Grant Pics: AIVRU Sliefield; IIelp: A.Zisserinan&C.hlarinos.

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