Journal of Visual Communication and Image Representation 12, 201–216 (2001) doi:10.1006/jvci.2000.0456, available online at http://www.idealibrary.com on Segmentation of Perspective Textured Planes through the Ridges of Continuous Wavelet Transform Wen-Liang Hwang Institute of Information Science, Academia Sinica, Taiwan Chun-Shien Lu Department of Electrical Engineering, National Cheng Kung University, Taiwan; and Institute of Information Science, Academia Sinica, Taiwan and Pau-Choo Chung Department of Electrical Engineering, National Cheng Kung University, Taiwan Received November 24, 1999; accepted April 15, 2000 A common assumption of the shape from texture problem is that a perceived image primarily contains only one type of texture with the same surface orientations. Unfor- tunately, a natural image is often composed of textured planes with different surface orientations. In order to deal with the shape from texture problem in a practical man- ner, we need to segment these surface orientations. The ridges are wavelet attributes in which information about spatial frequencies resides. In this paper, we propose a robust method for treating this problem from the ridges of continuous wavelet trans- form. We demonstrate the performance of our method on textured images synthesized from the Brodatz texture and several natural images. C  2001 Academic Press Key Words: wavelet transform; texture; segmentation; ridge; shape from texture. 1. INTRODUCTION Shape from texture methods estimate the surface orientations of a perspectively projected textured surface from a monocular image. In this article, we will consider when the surface is a plane. Readers should refer to [14–16] for solutions of shape from texture in a curved surface. A plane surface has an orientation, described by two angels: the slant angle, which determines the degree of obliqueness of the plane, and the tilt angle, which is the direction of the slant. In the literature, almost all the shape from texture methods assume that an image is composed of only one perspectively projected texture [2, 9, 11, 17]. However, 201 1047-3203/01 $35.00 Copyright C  2001 by Academic Press All rights of reproduction in any form reserved.