Digital Signal Processing. Konstantinos N. Plataniotis. Anastasios N. Venetsanopoulos Color Image Processing and Applications

Transcription

1 Digital Signal Processing Konstantinos N. Plataniotis. Anastasios N. Venetsanopoulos Color Image Processing and Applications

2 Springer-Verlag Berlin Heidelberg GmbH

3 Konstantinos N. Plataniotis Anastasios N. Venetsanopoulos Color Image Processing and Applications With 100 Figures, Springer

4 Series Editors Prof. Dr.-Ing. ARILD LACROIX Johann-Wolfgang-Goethe-Universität Institut für Angewandte Physik Robert-Mayer-Str.2-4 D Frankfurt Prof. ANASTASIOS N. VENETSANOPOULOS University of Toronto Department of Electrical & Computer Engineering 10 King's College Road M5S 3G4 Toronto, Ontario Canada Authors Ph. D. KONSTANTINOS N. PLATANIOTIS Prof. ANASTASIOS N. VENETSANOPOULOS University of Toronto Department of Electrical & Computer Engineering 10 King's College Road M5S 3G4 Toronto, Ontario Canada s: ISBN ISBN (ebook) DOI / Library of Congress Cataloging-in-Publication Data Plataniotis, Konstantinos N.: Color Image Processing and Applications / Konstantinos N. Plataniotis; Anastasios N. Venetsanopoulos. - Berlin; Heidelberg; New York; Barcelona; Hong Kong; London; Milano; Paris; Singapore; Tokyo: Springer 2000 (Digital Signal Processing) This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in other ways, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution act under German Copyright Law. Springer-Verlag Berlin Heidelberg 2000 Originally published by Springer-Verlag Berlin Heidelberg New York in Softcover reprint ofthe hardcover 1st edition 2000 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Digital data supplied by authors Cover-Design: de'blik, Berlin Printed on acid-free paper SPIN: /

5 Preface The perception of color is of paramount importance to humans since they routinely use color features to sense the environment, recognize objects and convey information. Color image processing and analysis is concerned with the manipulation of digital color images on a computer utilizing digital signal processing techniques. Like most advanced signal processing techniques, it was, until recently, confined to academic institut ions and research laboratories that could afford the expensive image processing hardware needed to handle the processing overhead required to process large numbers of color images. However, with the advent ofpowerful desktop computers and the proliferation of image collection devices, such as digital cameras and scanners, color image processing techniques are now within the grasp of the general public. This book is aimed at researchers and practitioners that work in the area of color image processing. Its purpose is to fill an existing gap in scientific literature by presenting the state of the art research in the area. It is written at a level which can be easily understood by a graduate student in an Electrical and Computer Engineering or Computer Science program. Therefore, it can be used as a textbook that covers part of a modern graduate course in digital image processing or multimedia systems. It can also be used as a textbook for a graduate course on digital signal processing since it contains algorithms, design criteria and architectures for processing and analysis systems. The book is structured into four parts. The first, Chapter 1, deals with color principles and is aimed at readers who have very little prior knowledge of color science. Readers interested in color image processing may read the second part of the book (Chapters 2-5). It covers the major, although somewhat mature, fields of color image processing. Color image processing is characterized by a large number of algorithms that are specific solutions to specific problems, for example vector median filters have been developed to remove impulsive noise from images. Some of them are mathematical or content independent operations that are applied to each and every pixel, such as morphological operators. Others are algorithmic in nature, in the sense that a recursive strategy may be necessary to find edge pixels in an image.

6 The third part ofthe book, Chapters 6-7, deals with color image analysis and co ding techniques. The ultimate goal of color image analysis is to enhance human-computer interaction. Recent applications of image analysis includes compression of color images either for transmission across the internetwork or co ding of video images for video conferencing. Finally, the fourth part (Chapter 8) covers emerging applications of color image processing. Color is useful for accessing multimedia databases. Local color information, for example in the form of color histograms, can be used to index and retrieve images from the database. Color features can also be used to identify objects of interest, such as human faces and hand areas, for applications ranging from video conferencing, to perceptual interfaces and virtual environments. Because of the dual nature of this investigation, processing and analysis, the logical dependen ce of the chapters is somewhat unusual. The following diagram can help the reader chart the course. ~1J ~ ~?d ~ ~J) ~@ ~S ~@ ~!l ~fj) Logical dependence between chapters

7 IX Acknowledgment We acknowledge a number of individuals who have contributed in different ways to the preparation of this book. In particular, we wish to extend our appreciation to Prof. M. Zervakis for contributing the image restoration section, and to Dr. N. Herodotou for his informative inputs and valuable suggestions in the emerging applications chapter. Three graduate students of ours also merit special thanks. Shu Yu Zhu for her input and high quality figures included in the color edge detection chapter, Ido Rabinovitch for his contribution to the color image coding section and Nicolaos Ikonomakis for his valuable contribution in the color segmentation chapter. We also thank Nicolaos for reviewing the chapters of the book and helping with the Latex formating of the manuscript. We also grateful to Terri Vlassopoulos for proofreading the manuscript, and Frank Holzwarth of Springer Verlag for his help during the preparation of the book. Finally, we are indebted to Peter Androutsos who helped us tremendously on the development of the companion software.

8 Contents 1. Color Spaces Basics of Color Vision The CIE Chromaticity-based Models The CIE-RGB Color Model Gamma Correction Linear and Non-linear RGB Color Spaces Linear RGB Color Space Non-linear RGB Color Space Color Spaces Linearly Related to the RGB The YIQ Color Space The HSI Family of Color Models Perceptually Uniform Color Spaces The CIE L*u*y* Color Space The CIE L*a*b* Color Space Cylindrical L*u*y* and L*a*b* Color Space Applications of L*u*y* and L*a*b* spaces The Munsell Color Space The Opponent Color Space New Trends Color Images Summary Color Image Filtering Introduction Color Noise Modeling Sensor Noise Modeling Transmission Noise Multiyariate Data Ordering Schemes Marginal Ordering Conditional Ordering Partial Ordering Reduced Ordering A Practical Example Vector Ordering

9 XII 2.8 The Distance Measures The Similarity Measures Filters Based On Marginal Ordering Filters Based on Reduced Ordering Filters Based on Vector Ordering Directional-based Filters Computational Complexity Conclusion Adaptive Image Filters Introduction The Adaptive Fuzzy System Determining the Parameters The Membership Function The Generalized Membership Function Members of the Adaptive Fuzzy Filter Family A Combined Fuzzy Directional and Fuzzy Median Filter Comments Application to l-d Signals The Bayesian Parametric Approach The Non-parametric Approach Adaptive Morphological Filters Introduction Computation of the NOP and the NCP Computational Complexity and Fast Algorithms Simulation Studies Conclusions Color Edge Detection Introduction Overview Of Color Edge Detection Methodology Techniques Extended From Monochrome Edge Detection Vector Space Approaches Vector Order Statistic Edge Operators Difference Vector Operators Evaluation Procedures and Results Probabilistic Evaluation Noise Performance Subjective Evaluation Conclusion

10 XIII 5. Color Image Enhancement and Restoration Introduction Histogram Equalization Color Image Restoration Restoration Algorithms Algorithm Formulation Definitions Direct Algorithms Robust Algorithms Conclusions Color Image Segmentation Introduction Pixel-based Techniques Histogram Thresholding Clustering Region-based Techniques Region Growing Split and Merge Edge-based Techniques Model-based Techniques The Maximum A-posteriori Method The Adaptive MAP Method Physics-based Techniques Hybrid Techniques Application Pixel Classification Seed Determination Region Growing Region Merging Results Conclusion Color Image Compression Introduction Image Compression Comparison Terminology Image Representation for Compression Applications Lossless Waveform-based Image Compression Techniques Entropy Co ding Lossless Compression Using Spatial Redundancy Lossy Waveform-based Image Compression Techniques Spatial Domain Methodologies Transform Domain Methodologies Second Generation Image Compression Techniques Perceptually Motivated Compression Techniques

11 XIV Modeling the Human Visual System Perceptually Motivated DCT Image Coding Perceptually Motivated Wavelet-based Coding Perceptually Motivated Region-based Coding Color Video Compression Conclusion Emerging Applications Input Analysis Using Color Information Shape and Color Analysis Fuzzy Membership Flmctions Aggregation Operators Experimental Results Conclusions A. Companion Image Processing Software A.1 Image Filtering A.2 Image Analysis A.3 Image Transforms A.4 Noise Generation Index

12 List of Figures 1.1 The visible light spectrum The CIE XYZ color matching functions The CIE RGB color matching functions The chromaticity diagram The Maxwell triangle The RGB color model Linear to Non-linear Light Transformation Non-linear to linear Light Transformation Transformation of Intensities from Image Capture to Image Display The HSI Color Space The HLS Color Space The HSV Color Space The L*u*v* Color Space The Munsell color system The Opponent color stage of the human visual system A taxonomy of color models Simulation I: Filter outputs (pt component) Simulation I: Filter outputs (2 nd component) Simulation Ir: Actual signal and noisy input (pt component) Simulation Ir: Actual signal and noisy input (2 nd component) Simulation Ir: Filter outputs (Ist component) Simulation Ir: Filter outputs (2 nd component) A flowchart of the NOP research algorithm The adaptive morphological filter 'Peppers' corrupted by 4% impulsive noise 'Lenna' corrupted with Gaussian noise (J = 15 mixed with 2% impulsive noise V M F of (3.9) using 3x3 window BV DF of (3.9) using 3x3 window HF of (3.9) using 3x3 window AH F of (3.9) using 3x3 window FV DF of (3.9) using 3x3 window ANNMF of (3.9) using 3x3 window CANNMF of (3.9) using 3x3 window

13 XVI 3.18 BFMA of (3.9) using 3x3 window V M F of (3.10) using 3x3 window BV DF of (3.10) using 3x3 window HF of (3.10) using 3x3 window AH F of (3.10) using 3x3 window FV DF of (3.10) using 3x3 window AN N M F of (3.10) using 3x3 window CANNMF of (3.10) using 3x3 window BF M A of (3.10) using 3x3 window 'Mandrill' - 10% impulsive noise NOP-NCP filtering results V M F using 3x3 window Mutistage Close-opening filtering results Edge detection by derivative operators Sub-window Configurations Test color image 'ellipse' Test color image 'flower' Test color image 'Lenna' Edge map of 'ellipse': Sobel detector Edge map of 'ellipse': VR detector Edge map of 'ellipse': DV detector Edge map of 'ellipse': DV llv detector Edge map of 'flower': Sobel detector Edge map of 'flower': VR detector Edge map of 'flower': DV detector Edge map of 'flower': DVadap detector Edge map of 'Lenna': Sobel detector Edge map of 'Lenna': VR detector Edge map of 'Lenna': DV detector Edge map of 'Lenna': DVadap detector The original color image 'mountain' The histogram equalized color output Partitioned image Corresponding quad-tree The HSI cone with achromatic region in yellow Original image. Achromatic pixels: intensity < 10, > Saturation< Saturation< Saturation< Original image. Achromatic pixels: saturation< 10, intensity> Intensity < Intensity <

14 XVII 6.11 Intensity < Original image. Achromatic pixels: saturation< 10, intensity< Intensity > Intensity > Intensity > Original image Pixel classification with chromatic pixels in red and achromatic pixels in the original color Original image Pixel classification with chromatic pixels in tan and achromatic pixels in the original color Artificial image with level 1, 2, and 3 seeds The region growing algorithm Original 'Claire' image 'Claire' image showing seeds with V AR = Segmented 'Claire' image (before merging), Tchrom = Segmented 'Claire' image (after merging), Tchrom = 0.15 and T merge = Original 'Carphone' image 'Carphone' image showing seeds with V AR = Segmented 'Carphone' image (before merging), Tchrom = Segmented 'Carphone' image (after merging), Tchrom = 0.15 and T merge = Original 'Mother-Daughter' image 'Mother-Daughter' image showing seeds with V AR = Segmented 'Mother-Daughter' image (before merging), Tchrom = Segmented 'Mother-Daughter' image (after merging), Tchrom = 0.15 and Tmerge = The zig-zag scan DCT based co ding Original color image 'Peppers' Image coded at a compression ratio 5 : Image coded at a compression ratio 6 : Image coded at a compression ratio 6.3 : Image coded at a compression ratio 6.35 : Image coded at a compression ratio 6.75 : Subband co ding scheme Relationship between different scale subspaces Multiresolution analysis decomposition The wavelet-based scheme Second generation co ding schemes The human visual system Overall operation of the processing module

15 XVIII 7.16 MPEG-1: Coding module MPEG-1: Decoding module Skin and Lip Clusters in the RGB color space Skin and Lip Clusters in the L*a*b* color space Skin and Lip hue Distributions in the HSV color space Overall scheme to extract the facial regions within a scene Template for hair color classification = R1 + R2 + R Carphone: Frame Segmented frame Frames Miss America: Frame Frames Akiyo: Frame Frames A.1 Screenshot of the main CIPAView window at startup A.2 Screenshot of Difference Vector Mean edge detector being applied 351 A.3 Gray scale image quantized to 4 levels A.4 Screenshot of an image being corrupted by Impulsive Noise

16 List of Tables 1.1 EBU Tech 3213 Primaries EBU Tech 3213 Primaries Color Model Computational Complexity Noise Distributions Filters Compared Subjective Image Evaluation Guidelines Figure of Merit NMSE(xl0-2 ) for the RGB 'Lenna' image, 3x3 window NMSE(xlO- 2 ) for the RGB 'Lenna' image, 5x5 window NMSE(xl0-2 ) for the RGB 'peppers' image, 3x3 window NMSE(xlO- 2 ) for the RGB 'peppers' image, 5x5 window NCD for the RGB 'Lenna' image, 3x3 window NCD for the RGB 'Lenna' image, 5x5 window NCD for the RGB 'peppers' image, 3x3 window NCD for the RGB 'peppers' image, 5x5 window Subjective Evaluation Performance measures für the image Mandrill Vector Order Statistic Operators Difference Vector Operators Numerical Evaluation with Synthetic Images Noise Performance Comparison of Chromatic Distance Measures Color Image Segmentation Techniques Storage requirements A taxonomy of image compression methodologies: First Generation A taxonomy of image compression methodologies: Second Generation Quantization table for the luminance component Quantization table für the chrominance components

17 xx 7.6 The JPEG suggested quantizatiün table Quantizatiün matrix based on the contrast sensitivity functiün für 1.0 min/pixel Miss America (Width x Height=360x 288):Shape & Color Analysis. 343