The  Weizmann  Institute  of  Science
Faculty of Mathematics and Computer Science

Vision and Robotics Seminar

Yair Weiss
School of Computer Science and Engineering
The Hebrew University

will speak on

Deriving intrinsic images from image sequences

Intrinsic images are a useful midlevel description of scenes proposed by Barrow and Tenenbaum (1978). An image is decomposed into two images: a reflectance image and an illumination image. Finding such a decomposition remains a difficult problem in computer vision. Here we focus on a slightly easier problem:  given a sequence of $T$ images where the reflectance is constant and the illumination changes, can we recover $T$ illumination images and a single reflectance image?  We show that this problem is still ill-posed and suggest approaching it as a maximum-likelihood estimation problem. Following recent work on the statistics of natural images, we use a prior that assumes that illumination images will give rise to sparse filter outputs. We show that this leads to a simple, novel algorithm for recovering reflectance images. We illustrate the algorithm's performance on real and synthetic image sequences.

The lecture will take place in the
Lecture Hall, Room 1, Ziskind Building
on Thursday, February 21, 2002
at noon