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

Abstract:

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