DOCSLIB.ORG

Color Image Perception, Representation and Contrast Enhancement

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Color Image Perception, Representation and Contrast Enhancement Yao Wang Tandon School of Engineering, New York University Why Study Image and Video Processing? • Purpose of image and video processing – Improvement of pictorial information for human interpretation – Compression of image and video data for storage and transmission – Preprocessing to enable object detection, classification, and tracking • Typical application areas – Television Signal Processing – Satellite Image Processing – Medical Image Processing – Robotics – Visual Communications – Law Enforcement – Etc. © Yao Wang, 2016 EL-GY 6123 2 Breakdown of the Course • Image processing basics • Video processing basics • Image and video compression • Stereo and multiview image/video basics © Yao Wang, 2016 EL-GY 6123 3 Today’s Lecture • Color perception • Color production using primary colors • Color specification • Color image representation • Image capture and display • Image contrast measurement using histograms • Image contrast enhancement © Yao Wang, 2016 EL-GY 6123 4 Color Perception and Specification • Light -> color perception • Human perception of color • Type of light sources • Trichromatic color mixing theory • Specification of color – Tristimulus representation – Luminance/Chrominance representation • Color coordinate conversion © Yao Wang, 2016 EL-GY 6123 5 Light is part of the EM wave from [Gonzalez02] © Yao Wang, 2016 EL-GY 6123 6 Illuminating and Reflecting Light • Illuminating sources: – emit light (e.g. the sun, light bulb, TV monitors) – perceived color depends on the emitted freq. – follows additive rule • R+G+B=White • Reflecting sources: – reflect an incoming light (e.g. the color dye, matte surface, cloth) – perceived color depends on reflected freq (=emitted freq- absorbed freq.) – follows subtractive rule • R+G+B=Black © Yao Wang, 2016 EL-GY 6123 7 Eye Anatomy From http://www.stlukeseye.com/Anatomy.asp © Yao Wang, 2016 EL-GY 6123 8 Eye vs. Camera Camera components Eye components Lens Lens, cornea Shutter Iris, pupil Film Retina Cable to transfer images Optic nerve send the info to the brain © Yao Wang, 2016 EL-GY 6123 9 Human Perception of Color • Retina contains photo receptors – Cones: day vision, can perceive color tone • Red, green, and blue cones • Different cones have different frequency responses • Tri-receptor theory of color vision [Young1802] – Rods: night vision, perceive brightness From http://www.macula.org/ only anatomy/retinaframe.html • Color sensation is characterized by – Luminance (brightness) – Chrominance • Hue (color tone) • Saturation (color purity) © Yao Wang, 2016 EL-GY 6123 10 Frequency Responses of Cones and the Luminous Efficiency Function Ci = ∫C(λ)ai (λ)dλ, i = r, g,b, y © Yao Wang, 2016 EL-GY 6123 11 Three Attributes of Color • Luminance (brightness) • Chrominance – Hue (color tone) and Saturation (color purity) • Represented by a “color cone” θ © Yao Wang, 2016 EL-GY 6123 12 Trichromatic Color Mixing • Trichromatic color mixing theory – Any (actually most) color can be obtained by mixing three primary colors with a right proportion C = ∑TkCk , Tk : Tristimulus values k=1,2,3 • Primary colors for illuminating sources: – Red, Green, Blue (RGB) – Color monitor works by exciting red, green, blue phosphors using separate electronic guns • Primary colors for reflecting sources (also known as secondary colors): – Cyan, Magenta, Yellow (CMY) – Color printer works by using cyan, magenta, yellow and black (CMYK) dyes © Yao Wang, 2016 EL-GY 6123 13 RGB vs CMY Magenta = Red + Blue Magenta = White - Green Cyan = Blue + Green Cyan = White - Red Yellow = Green + Red Yellow = White - Blue © Yao Wang, 2016 EL-GY 6123 14 red Green Blue © Yao Wang, 2016 EL-GY 6123 15 Tristimulus Values and Chromaticity • Tristimulus values – The amounts of three primary colors needed to form any particular color are called the tristimulus values, denoted by X, Y, and Z (or any other three symbols). • Trichromatic (or chromaticity) coefficients X Y Z x = , y = , z = . X +Y + Z X +Y + Z X +Y + Z – Only two chromaticity coefficients are necessary to specify the chrominance of a light. x + y + z =1 © Yao Wang, 2016 EL-GY 6123 16 Problems with Using Primary Colors for Color Representation • Tristimulus values depend on the primary colors used by the camera/display • Tristimulus values may be negative for some visible colors • How to compare colors obtained using different devices • Need for standardization • Standard using physical primary colors (CIE RGB) • Standard using imaginary primary colors (CIE XYZ): device invariant • Colors captured by cameras using different physical RGB primaries can be converted to the standard XYZ representation • CIE: International commission on illumination © Yao Wang, 2016 EL-GY 6123 17 CIE XYZ Color Space • Use imaginary color primaries X, Y, Z so that the tristimulus values are all non-negative • Encompasses all visible colors by an average person • Device invariant color representation • Color primaries used by each device can be specified using XYZ values • Colors captured by cameras using different physical RGB primaries can be converted to the standard XYZ representation © Yao Wang, 2016 EL-GY 6123 18 CIE XYZ Color Matching Functions https://en.wikipedia.org/wiki/ CIE_1931_color_space • Y approximates the brightness ~= green cone response of an average person (standard observer) • Z approximates the blue cone response of an average person • X is NOT red, rather derived so that XY,Z values for all visible colors are all >=0. © Yao Wang, 2016 EL-GY 6123 19 CIE Chromaticity Diagram • Colors on the boundary: spectrum colors, highest saturation • Shows all visible colors by humans • Mixing any three colors in the visible range can generate colors in the triangle formed by these three points. © Yao Wang, 2016 EL-GY 6123 from [Gonzalez02] 20 Color Gamut of Monitors and Printers • Not all visible colors can be reproduced by RGB primaries used for display, or CMY primaries used for printing. • The triangle: gamut of color monitors using the Red, Green, and Blue colors at the corner as primary colors • The irregular region inside: gamut of most color printers • A printer cannot reproduce all colors that you see on the screen! © Yao Wang, 2016 EL-GY 6123 21 CIE RGB Color Space • Using single spedtral color for primary colors: – 700 nm (R), 546.1 nm (G), 435.8nm (B) • Color matching functions are the amounts of primaries needed to match each single https://en.wikipedia.org/wiki/CIE_1931_color_space spectral color © Yao Wang, 2016 EL-GY 6123 22 Color Primary Defined by ITU Rec. 709 for HDTV ! R $ ! 3.240479 −1.537150 −0.498535 $! X $ # & # &# & # G & = # −0.969256 1.875992 0.041556 &# Y & # & # &# Z & " B % " 0.055648 −0.204043 1.057311 %" % ! X $ ! 0.412453 0.357580 0.180423 $! R $ # & # &# & # Y & = # 0.212671 0.715160 0.072169 &# G & # Z & # &# & " % " 0.019334 0.119193 0.950277 %" B % The three columns in the RGB-> XYZ conversion are the tristimulus values of the R,G,B primaries defined in terms of CIE XYZ primaries. From these, you could derive the chromaticity coefficients of RGB primaries and correspondingly locate them in the CIE diagram (HW!) © Yao Wang, 2016 EL-GY 6123 23 Comparison of Colors Defined Using Different Primiaries • To compare colors defined using different primaries, we should convert them all to CIE XYZ primaries and compare their XYZ values © Yao Wang, 2016 EL-GY 6123 24 Color Representation Models • Specify the tristimulus values associated with the three primary colors – RGB, CMY, XYZ • Specify the luminance and chrominance – HSI (Hue, saturation, intensity) – YIQ (used in NTSC color TV) – YCbCr (used in digital color TV) • Amplitude specification: – 8 bits for each color component, or 24 bits total for each pixel – Total of 16 million colors – A true RGB color display of size 1Kx1K requires a display buffer memory size of 3 MB • High dynamic range (HDR) Image: up to 16 bits/component © Yao Wang, 2016 EL-GY 6123 25 HSI Color Model • Hue represents dominant color as perceived by an observer. It is an attribute associated with the dominant wavelength. • Saturation refers to the relative purity or the amount of white light mixed with a hue. The pure spectrum colors are fully saturated. Pink and lavender are less saturated. • Intensity reflects the brightness. © Yao Wang, 2016 EL-GY 6123 26 Conversion Between RGB and HSI • Converting from RGB to HSI ⎧ 1 ⎫ [(R − G) + (R − B)] ⎧ θ if B ≤ G 1⎪ ⎪ H with cos− 2 = ⎨ θ = ⎨ 1 ⎬ ⎩360 −θ if B > G 2 ⎪ (R G) (R B)(G B) 2 ⎪ ⎩⎪[ − + − − ] ⎭⎪ 3 S = 1− [min(R,G, B)] (R + G + B) 1 I = [R + G + B] 3 • Converting from HSI to RGB RG sector (0≤H<120) GB sector (120≤H<240) BR sector (240≤H<360) B = I(1− S) R = I(1− S) G = I(1− S) ⎡ S cos H ⎤ ⎡ S cos(H −120) ⎤ ⎡ S cos(H − 240) ⎤ R I 1 G = I 1+ B = I 1+ = ⎢ + ⎥ ⎢ cos(60 (H 120))⎥ ⎢ ⎥ ⎣ cos(60 − H )⎦ ⎣ − − ⎦ ⎣ cos(60 − (H − 240))⎦ G =1− (R + B) B =1− (R + G) R =1− (G + B) © Yao Wang, 2016 EL-GY 6123 from [Gonzalez02] 27 YIQ Color Coordinate System • YIQ is defined by the National Television System Committee (NTSC) for US analog color TV system – Y describes the luminance, I and Q describes the chrominance. – A more compact representation of the color. – YUV plays similar role in PAL and SECAM. • Conversion between RGB and YIQ ⎡Y ⎤ ⎡0.299 0.587 0.114 ⎤⎡R⎤ ⎡R⎤ ⎡1.0 0.956 0.621 ⎤⎡Y ⎤ ⎢ I ⎥ ⎢0.596 0.274 0.322⎥⎢G⎥, ⎢G⎥ ⎢1.0 0.272 0.649⎥⎢ I ⎥ ⎢ ⎥ = ⎢ − − ⎥⎢ ⎥ ⎢ ⎥ = ⎢ − − ⎥⎢ ⎥ ⎣⎢Q⎦⎥ ⎣⎢0.211 − 0.523 0.311 ⎦⎥⎣⎢B⎦⎥ ⎣⎢B⎦⎥ ⎣⎢1.0 −1.106 1.703 ⎦⎥⎣⎢Q⎦⎥ © Yao Wang, 2016 EL-GY 6123 28 YUV/YCbCr Coordinate • YUV is the color coordinate
Recommended publications
  • Image Processing Terms Used in This Section Working with Different Screen Bit Describes How to Determine the Screen Bit Depth of Your Depths (P

    Image Processing Terms Used in This Section Working with Different Screen Bit Describes How to Determine the Screen Bit Depth of Your Depths (P

    13 Color This section describes the toolbox functions that help you work with color image data. Note that “color” includes shades of gray; therefore much of the discussion in this chapter applies to grayscale images as well as color images. Topics covered include Terminology (p. 13-2) Provides definitions of image processing terms used in this section Working with Different Screen Bit Describes how to determine the screen bit depth of your Depths (p. 13-3) system and provides recommendations if you can change the bit depth Reducing the Number of Colors in an Describes how to use imapprox and rgb2ind to reduce the Image (p. 13-6) number of colors in an image, including information about dithering Converting to Other Color Spaces Defines the concept of image color space and describes (p. 13-15) how to convert images between color spaces 13 Color Terminology An understanding of the following terms will help you to use this chapter. Terms Definitions Approximation The method by which the software chooses replacement colors in the event that direct matches cannot be found. The methods of approximation discussed in this chapter are colormap mapping, uniform quantization, and minimum variance quantization. Indexed image An image whose pixel values are direct indices into an RGB colormap. In MATLAB, an indexed image is represented by an array of class uint8, uint16, or double. The colormap is always an m-by-3 array of class double. We often use the variable name X to represent an indexed image in memory, and map to represent the colormap. Intensity image An image consisting of intensity (grayscale) values.
  • Real-Time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location

    Real-Time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location

    Missouri University of Science and Technology Scholars' Mine Electrical and Computer Engineering Faculty Research & Creative Works Electrical and Computer Engineering 01 Nov 2015 Real-Time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location Ravneet Kaur P. P. Albano Justin G. Cole Jason R. Hagerty et. al. For a complete list of authors, see https://scholarsmine.mst.edu/ele_comeng_facwork/3045 Follow this and additional works at: https://scholarsmine.mst.edu/ele_comeng_facwork Part of the Chemistry Commons, and the Electrical and Computer Engineering Commons Recommended Citation R. Kaur et al., "Real-Time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location," Skin Research and Technology, vol. 21, no. 4, pp. 466-473, John Wiley & Sons, Nov 2015. The definitive version is available at https://doi.org/10.1111/srt.12216 This Article - Journal is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in Electrical and Computer Engineering Faculty Research & Creative Works by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. Published in final edited form as: Skin Res Technol. 2015 November ; 21(4): 466–473. doi:10.1111/srt.12216. Real-time Supervised Detection of Pink Areas in Dermoscopic Images of Melanoma: Importance of Color Shades, Texture and Location Ravneet Kaur, MS, Department of Electrical and Computer Engineering, Southern Illinois University Edwardsville, Campus Box 1801, Edwardsville, IL 62026-1801, Telephone: 618-210-6223, [email protected] Peter P.
  • Alternative Processes a Few Essentials Introduction

    Alternative Processes a Few Essentials Introduction

    Alternative Processes A Few Essentials Introduction Chapter 1. Capture Techniques From Alternative Photographic Processes: Crafting Handmade Images Chapter 2. Digital Negatives for Gum From Gum Printing: A Step-by-Step Manual, Highlighting Artists and Their Creative Practice Chapter 3. Fugitive and Not-So-Fugitive Printing From Jill Enfield?s Guide to Photographic Alternative Processes: Popular Historical and Contemporary Techniques 2 Featured Books on Alternative Process Photography from Routledge | Focal Press Use discount code FLR40 to take 20% off all Routledge titles. Simply visit www.routledge.com/photography to browse and purchase books of interest. 3 Introduction A young art though it may be, photography already has a rich history. As media moves full steam ahead into the digital revolution and beyond, it is a natural instinct to look back at where we?ve come from. With more artists rediscovering photography?s historical processes, the practice of photography continually redefines and re-contextualizes itself. The creative possibilities of these historical processes are endless, spawning a growing arena of practice - alternative processes, which combines past, present and everything in between, in the creation of art. This collection is an introduction to and a sample of these processes and possibilities. With Alternative Photographic Processes, Brady Wilks demonstrates techniques for manipulating photographs, negatives and prints ? emphasizing the ?hand-made? touch. Bridging the gap between the simplest of processes to the most complex, Wilks? introduction demonstrates image-manipulation pre-capture, allowing the artist to get intimate with his or her images long before development. In the newly-released Gum Printing, leading gum expert Christina Z.
  • Accurately Reproducing Pantone Colors on Digital Presses

    Accurately Reproducing Pantone Colors on Digital Presses

    Accurately Reproducing Pantone Colors on Digital Presses By Anne Howard Graphic Communication Department College of Liberal Arts California Polytechnic State University June 2012 Abstract Anne Howard Graphic Communication Department, June 2012 Advisor: Dr. Xiaoying Rong The purpose of this study was to find out how accurately digital presses reproduce Pantone spot colors. The Pantone Matching System is a printing industry standard for spot colors. Because digital printing is becoming more popular, this study was intended to help designers decide on whether they should print Pantone colors on digital presses and expect to see similar colors on paper as they do on a computer monitor. This study investigated how a Xerox DocuColor 2060, Ricoh Pro C900s, and a Konica Minolta bizhub Press C8000 with default settings could print 45 Pantone colors from the Uncoated Solid color book with only the use of cyan, magenta, yellow and black toner. After creating a profile with a GRACoL target sheet, the 45 colors were printed again, measured and compared to the original Pantone Swatch book. Results from this study showed that the profile helped correct the DocuColor color output, however, the Konica Minolta and Ricoh color outputs generally produced the same as they did without the profile. The Konica Minolta and Ricoh have much newer versions of the EFI Fiery RIPs than the DocuColor so they are more likely to interpret Pantone colors the same way as when a profile is used. If printers are using newer presses, they should expect to see consistent color output of Pantone colors with or without profiles when using default settings.
  • A Digital Astrophotography Primer - OR - This Is NOT Your Daddy’S SLR!

    A Digital Astrophotography Primer - OR - This Is NOT Your Daddy’S SLR!

    A Digital Astrophotography Primer - OR - This is NOT your Daddy’s SLR! Page 1 of 22 Table of Contents A Digital Astrophotography Primer...........................................................................................................................................................1 Table of Contents.......................................................................................................................................................................................2 Introduction............................................................................................................................................................................................3 What is an SLR, anyways? ....................................................................................................................................................................3 SLR, DSLR, What’s the Difference?.....................................................................................................................................................4 The Viewfinder ......................................................................................................................................................................................4 The Focus Mechanism ...........................................................................................................................................................................5 The Capture Medium .............................................................................................................................................................................6
  • Predictability of Spot Color Overprints

    Predictability of Spot Color Overprints

    Predictability of Spot Color Overprints Robert Chung, Michael Riordan, and Sri Prakhya Rochester Institute of Technology School of Print Media 69 Lomb Memorial Drive, Rochester, NY 14623, USA emails: [email protected], [email protected], [email protected] Keywords spot color, overprint, color management, portability, predictability Abstract Pre-media software packages, e.g., Adobe Illustrator, do amazing things. They give designers endless choices of how line, area, color, and transparency can interact with one another while providing the display that simulates printed results. Most prepress practitioners are thrilled with pre-media software when working with process colors. This research encountered a color management gap in pre-media software’s ability to predict spot color overprint accurately between display and print. In order to understand the problem, this paper (1) describes the concepts of color portability and color predictability in the context of color management, (2) describes an experimental set-up whereby display and print are viewed under bright viewing surround, (3) conducts display-to-print comparison of process color patches, (4) conducts display-to-print comparison of spot color solids, and, finally, (5) conducts display-to-print comparison of spot color overprints. In doing so, this research points out why the display-to-print match works for process colors, and fails for spot color overprints. Like Genie out of the bottle, there is no turning back nor quick fix to reconcile the problem with predictability of spot color overprints in pre-media software for some time to come. 1. Introduction Color portability is a key concept in ICC color management.
  • Digital Negative (DNG) Specification

    Digital Negative (DNG) Specification

    Digital Negative (DNG) Ë Specification Version 1.1.0.0 February 2005 ADOBE SYSTEMS INCORPORATED Corporate Headquarters 345 Park Avenue San Jose, CA 95110-2704 (408) 536-6000 http://www.adobe.com Copyright © 2004-2005 Adobe Systems Incorporated. All rights reserved. NOTICE: All information contained herein is the property of Adobe Systems Incorporated. No part of this publication (whether in hardcopy or electronic form) may be reproduced or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written consent of Adobe Systems Incorporated. Adobe, the Adobe logo, and Photoshop are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries. All other trademarks are the property of their respective owners. This publication and the information herein is furnished AS IS, is subject to change without notice, and should not be construed as a commitment by Adobe Systems Incorporated. Adobe Systems Incorporated assumes no responsibility or liability for any errors or inaccuracies, makes no warranty of any kind (express, implied, or statutory) with respect to this publication, and expressly disclaims any and all warranties of merchantability, fitness for particular purposes, and noninfringement of third party rights. Table of Contents Preface . .vii About This Document . vii Audience . vii How This Document Is Organized . vii Where to Go for More Information . viii Chapter 1 Introduction . 9 The Pros and Cons of Raw Data. 9 A Standard Format . 9 The Advantages of DNG . 10 Chapter 2 DNG Format Overview . .11 File Extensions . 11 SubIFD Trees . 11 Byte Order . 11 Masked Pixels .
  • The DIGITAL NEGATIVE & PRINT Books

    The DIGITAL NEGATIVE & PRINT Books

    THE DIGITAL NEGATIVE Raw Image Processing in Lightroom, Camera Raw, and Photoshop JEFF SCHEWE Peachpit Press THE DIGITAL NEGATIVE RAW IMAGE PROCEssING IN LIGHTROOM, CAMERA RAW, AND PHOTOSHOP Jeff Schewe PEACHPIT PREss www.peachpit.com To report errors, please send a note to: [email protected] Peachpit Press is a division of Pearson Education. Copyright © 2013 by Jeff Schewe Acquisitions Editor: Rebecca Gulick Production Editor: Lisa Brazieal Development and Copy Editor: Elizabeth Kuball Compositor: Kim Scott/Bumpy Design Proofreader: Patricia Pane Indexer: Emily Glossbrenner Cover and Interior Designer: Mimi Heft NOTICE OF RIGHTS All rights reserved. No part of this book may be reproduced or transmitted in any form by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. For information on getting permission for reprints and excerpts, contact [email protected]. NOTICE OF LIABILITY The information in this book is distributed on an “As Is” basis, without warranty. While every precau- tion has been taken in the preparation of the book, neither the author nor Peachpit Press shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the instructions contained in this book or by the computer software and hardware products described in it. TrADEMARKS Adobe, Adobe Bridge, Adobe Camera Raw, Lightroom, and Photoshop are registered trademarks of Adobe Systems Incorporated in the United States and/or other countries. All other trademarks are the property of their respective owners. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks.
  • Certified Digital Designer Professional Certification Examination Review

    Certified Digital Designer Professional Certification Examination Review

    Digital Imaging & Editing and Digital & General Photography Certified Digital Designer Professional Certification Examination Review Within this presentation – We will use specific names and terminologies. These will be related to specific products, software, brands and trade names. ADDA does not endorse any specific software or manufacturer. It is the sole decision of the individual to choose and purchase based on their personal preference and financial capabilities. the Examination Examination Contain at Total 325 Questions 200 Questions in Digital Image Creation and Editing Image Editing is applicable to all Areas related to Digital Graphics 125 Question in Photography Knowledge and History Photography is applicable to General Principles of Photography Does not cover Photography as a General Arts Program Examination is based on entry level intermediate employment knowledge Certain Processes may be omitted that are required to achieve an end result ADDA Professional Certification Series – Digital Imaging & Editing the Examination Knowledge of Graphic and Photography Acronyms Knowledge of Graphic Program Tool Symbols Some Knowledge of Photography Lighting Ability to do some basic Geometric Calculations Basic Knowledge of Graphic History & Theory Basic Knowledge of Digital & Standard Film Cameras Basic Knowledge of Camera Lens and Operation General Knowledge of Computer Operation Some Common Sense ADDA Professional Certification Series – Digital Imaging & Editing This is the Comprehensive Digital Imaging & Editing Certified Digital Designer Professional Certification Examination Review Within this presentation – We will use specific names and terminologies. These will be related to specific products, software, brands and trade names. ADDA does not endorse any specific software or manufacturer. It is the sole decision of the individual to choose and purchase based on their personal preference and financial capabilities.
  • Color Images, Color Spaces and Color Image Processing

    Color Images, Color Spaces and Color Image Processing

    color images, color spaces and color image processing Ole-Johan Skrede 08.03.2017 INF2310 - Digital Image Processing Department of Informatics The Faculty of Mathematics and Natural Sciences University of Oslo After original slides by Fritz Albregtsen today’s lecture ∙ Color, color vision and color detection ∙ Color spaces and color models ∙ Transitions between color spaces ∙ Color image display ∙ Look up tables for colors ∙ Color image printing ∙ Pseudocolors and fake colors ∙ Color image processing ∙ Sections in Gonzales & Woods: ∙ 6.1 Color Funcdamentals ∙ 6.2 Color Models ∙ 6.3 Pseudocolor Image Processing ∙ 6.4 Basics of Full-Color Image Processing ∙ 6.5.5 Histogram Processing ∙ 6.6 Smoothing and Sharpening ∙ 6.7 Image Segmentation Based on Color 1 motivation ∙ We can differentiate between thousands of colors ∙ Colors make it easy to distinguish objects ∙ Visually ∙ And digitally ∙ We need to: ∙ Know what color space to use for different tasks ∙ Transit between color spaces ∙ Store color images rationally and compactly ∙ Know techniques for color image printing 2 the color of the light from the sun spectral exitance The light from the sun can be modeled with the spectral exitance of a black surface (the radiant exitance of a surface per unit wavelength) 2πhc2 1 M(λ) = { } : λ5 hc − exp λkT 1 where ∙ h ≈ 6:626 070 04 × 10−34 m2 kg s−1 is the Planck constant. ∙ c = 299 792 458 m s−1 is the speed of light. ∙ λ [m] is the radiation wavelength. ∙ k ≈ 1:380 648 52 × 10−23 m2 kg s−2 K−1 is the Boltzmann constant. T ∙ [K] is the surface temperature of the radiating Figure 1: Spectral exitance of a black body surface for different body.
  • Film Printing

    Film Printing

    1 2 3 4 5 6 7 8 9 10 1 2 3 Film Technology in Post Production 4 5 6 7 8 9 20 1 2 3 4 5 6 7 8 9 30 1 2 3 4 5 6 7 8 9 40 1 2 3111 This Page Intentionally Left Blank 1 2 3 Film Technology 4 5 6 in Post Production 7 8 9 10 1 2 Second edition 3 4 5 6 7 8 9 20 1 Dominic Case 2 3 4 5 6 7 8 9 30 1 2 3 4 5 6 7 8 9 40 1 2 3111 4 5 6 7 8 Focal Press 9 OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI 1 Focal Press An imprint of Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd A member of the Reed Elsevier plc group First published 1997 Reprinted 1998, 1999 Second edition 2001 © Dominic Case 2001 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 0LP. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging in Publication Data A catalogue record
  • Compendium for Digital Photography

    Compendium for Digital Photography

    English translation sponsored by: English translation sponsored by: Image Engineering COMPENDIUM FOR DIGITAL PHOTOGRAPHY A cooperation of : Compendium for digital photography 1 English translation sponsored by: Image Engineering Preambel Dear readers. The "Compendium for digital photography" aka. "DigiPix" in version 3 was originally written and published November 2004 in and by the cooperation of the adf (Working Group Digital Photography) and the ECI (European Color Initiative) - in german only. With the kind of posi- tive acceptance we received in public the idea of an international ver- sion available in english was soon born and eventually realized. Due to the fast paced innovation in the field of digital photography and digital imaging in general some areas of this guide are not up-to-date with the latest and greatest. An updated version will be available in the near future. Meanwhile the authoring team hopes to provide you, the photog- rapher with a batch of tips and helpful background info, in order to make your daily digital job a lot easier. I would like to thank the sponsors, Image Engineering Dietmar Wüller, Tecco Braun & Frings GmbH and LaserSoft Imaging AG for making this translation possible through their much appreciated support. We wanted to make sure that this publication can be used as freely as possible which is why we issued CREATIVE COMMONS PUBLIC LICENSE at the end of this document. We the authors expect the compliance with it. Jan-Willem Rossée September of 2006 ([email protected]) The authors: adf (workingroup digital photography): Reinhard Fittkau, Holger Hagedorn, Dirk Hartmann, Dr. Martin Knapp, Matthias Weise ECI: Dieter Dolezal, Dietmar Fuchs, Jan-Willem Rossée, Andre Schützen- hofer, Dietmar Wueller weitere Autoren: Ulrike Haessler, Christian Westphalen 2 Compendium for digital photography English translation sponsored by: Image Engineering Content Preamble 2 Content 3 1.