Nonlinear Techniques for Color Image Processing - Nonlinear Signal and Image Processing: Theory, Methods and Applications - page 445

12

Nonlinear Techniques for Color
Image Proce ssing

Bogdan Smolka, Konstantinos N. Plataniotis,
and Anastasios N. Venetsanopoulos

CONTENTS
12.1 Introduction .......................................................... 445

12.2 Adaptive Noise Reduction Filtering ................................. 448

12.3 Anisotropic Diffusion ................................................ 453

12.4 Noise Reduction Filters for Color Image Processing ................ 460

12.5 Digital Paths Approach to Color Image Filtering ................... 471

12.6 Efficiency of the New Filter Class ................................... 486

Acknowledgment .......................................................... 498

References .................................................................. 499

12.1 Introduction
The perception of color is of paramount importance to humans because they
routinely use color features to sense the environment, recognize objects, and
convey information. That is the reason why it is necessary to use color infor-
mation for computer vision, because in many practical cases location of scene
objects can be obtained only when color information is considered. 1
Noise filtering is one of the most important tasks in many image analy-
sis and computer vision applications. Its goal is the removal of unprofitable
information that may corrupt any of the subsequent image processing steps.
The reduction of noise in digital images without degradation of the un-
derlying image structures has attracted much interest in the last years. 2-8 Re-
cently, increasing attention has been given to nonlinear processing of vector-
valued signals. Many of the techniques used for color noise reduction are
direct implementations of the methods used for gray-scale imaging. The in-
dependent processing of color image channels is, however, inappropriate and
leads to strong artifacts. To overcome this problem, the standard techniques