Development and Application of Color Appearance Phenomenon and Color Appearance Model
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Color Models
Color Models Jian Huang CS456 Main Color Spaces • CIE XYZ, xyY • RGB, CMYK • HSV (Munsell, HSL, IHS) • Lab, UVW, YUV, YCrCb, Luv, Differences in Color Spaces • What is the use? For display, editing, computation, compression, …? • Several key (very often conflicting) features may be sought after: – Additive (RGB) or subtractive (CMYK) – Separation of luminance and chromaticity – Equal distance between colors are equally perceivable CIE Standard • CIE: International Commission on Illumination (Comission Internationale de l’Eclairage). • Human perception based standard (1931), established with color matching experiment • Standard observer: a composite of a group of 15 to 20 people CIE Experiment CIE Experiment Result • Three pure light source: R = 700 nm, G = 546 nm, B = 436 nm. CIE Color Space • 3 hypothetical light sources, X, Y, and Z, which yield positive matching curves • Y: roughly corresponds to luminous efficiency characteristic of human eye CIE Color Space CIE xyY Space • Irregular 3D volume shape is difficult to understand • Chromaticity diagram (the same color of the varying intensity, Y, should all end up at the same point) Color Gamut • The range of color representation of a display device RGB (monitors) • The de facto standard The RGB Cube • RGB color space is perceptually non-linear • RGB space is a subset of the colors human can perceive • Con: what is ‘bloody red’ in RGB? CMY(K): printing • Cyan, Magenta, Yellow (Black) – CMY(K) • A subtractive color model dye color absorbs reflects cyan red blue and green magenta green blue and red yellow blue red and green black all none RGB and CMY • Converting between RGB and CMY RGB and CMY HSV • This color model is based on polar coordinates, not Cartesian coordinates. -
Chapter 6 : Color Image Processing
Chapter 6 : Color Image Processing CCU, Taiwan Wen-Nung Lie Color Fundamentals Spectrum that covers visible colors : 400 ~ 700 nm Three basic quantities Radiance : energy that flows from the light source (measured in Watts) Luminance : a measure of energy an observer perceives from a light source (in lumens) Brightness : a subjective descriptor difficult to measure CCU, Taiwan Wen-Nung Lie 6-1 About human eyes Primary colors for standardization blue : 435.8 nm, green : 546.1 nm, red : 700 nm Not all visible colors can be produced by mixing these three primaries in various intensity proportions Cones in human eyes are divided into three sensing categories 65% are sensitive to red light, 33% sensitive to green light, 2% sensitive to blue (but most sensitive) The R, G, and B colors perceived by CCU, Taiwan human eyes cover a range of spectrum Wen-Nung Lie 6-2 Primary and secondary colors of light and pigments Secondary colors of light magenta (R+B), cyan (G+B), yellow (R+G) R+G+B=white Primary colors of pigments magenta, cyan, and yellow M+C+Y=black CCU, Taiwan Wen-Nung Lie 6-3 Chromaticity Hue + saturation = chromaticity hue : an attribute associated with the dominant wavelength or dominant colors perceived by an observer saturation : relative purity or the amount of white light mixed with a hue (the degree of saturation is inversely proportional to the amount of added white light) Color = brightness + chromaticity Tristimulus values (the amount of R, G, and B needed to form any particular color : X, Y, Z trichromatic -
The Art of Digital Black & White by Jeff Schewe There's Just Something
The Art of Digital Black & White By Jeff Schewe There’s just something magical about watching an image develop on a piece of photo paper in the developer tray…to see the paper go from being just a blank white piece of paper to becoming a photograph is what many photographers think of when they think of Black & White photography. That process of watching the image develop is what got me hooked on photography over 30 years ago and Black & White is where my heart really lives even though I’ve done more color work professionally. I used to have the brown stains on my fingers like any good darkroom tech, but commercially, I turned toward color photography. Later, when going digital, I basically gave up being able to ever achieve what used to be commonplace from the darkroom–until just recently. At about the same time Kodak announced it was going to stop making Black & White photo paper, Epson announced their new line of digital ink jet printers and a new ink, Ultrachrome K3 (3 Blacks- hence the K3), that has given me hope of returning to darkroom quality prints but with a digital printer instead of working in a smelly darkroom environment. Combine the new printers with the power of digital image processing in Adobe Photoshop and the capabilities of recent digital cameras and I think you’ll see a strong trend towards photographers going digital to get the best Black & White prints possible. Making the optimal Black & White print digitally is not simply a click of the shutter and push button printing. -
Fast and Stable Color Balancing for Images and Augmented Reality
Fast and Stable Color Balancing for Images and Augmented Reality Thomas Oskam 1,2 Alexander Hornung 1 Robert W. Sumner 1 Markus Gross 1,2 1 Disney Research Zurich 2 ETH Zurich Abstract This paper addresses the problem of globally balanc- ing colors between images. The input to our algorithm is a sparse set of desired color correspondences between a source and a target image. The global color space trans- formation problem is then solved by computing a smooth Source Image Target Image Color Balanced vector field in CIE Lab color space that maps the gamut of the source to that of the target. We employ normalized ra- dial basis functions for which we compute optimized shape parameters based on the input images, allowing for more faithful and flexible color matching compared to existing RBF-, regression- or histogram-based techniques. Further- more, we show how the basic per-image matching can be Rendered Objects efficiently and robustly extended to the temporal domain us- Tracked Colors balancing Augmented Image ing RANSAC-based correspondence classification. Besides Figure 1. Two applications of our color balancing algorithm. Top: interactive color balancing for images, these properties ren- an underexposed image is balanced using only three user selected der our method extremely useful for automatic, consistent correspondences to a target image. Bottom: our extension for embedding of synthetic graphics in video, as required by temporally stable color balancing enables seamless compositing applications such as augmented reality. in augmented reality applications by using known colors in the scene as constraints. 1. Introduction even for different scenes. With today’s tools this process re- quires considerable, cost-intensive manual efforts. -
Chapter 2 Fundamentals of Digital Imaging
Chapter 2 Fundamentals of Digital Imaging Part 4 Color Representation © 2016 Pearson Education, Inc., Hoboken, 1 NJ. All rights reserved. In this lecture, you will find answers to these questions • What is RGB color model and how does it represent colors? • What is CMY color model and how does it represent colors? • What is HSB color model and how does it represent colors? • What is color gamut? What does out-of-gamut mean? • Why can't the colors on a printout match exactly what you see on screen? © 2016 Pearson Education, Inc., Hoboken, 2 NJ. All rights reserved. Color Models • Used to describe colors numerically, usually in terms of varying amounts of primary colors. • Common color models: – RGB – CMYK – HSB – CIE and their variants. © 2016 Pearson Education, Inc., Hoboken, 3 NJ. All rights reserved. RGB Color Model • Primary colors: – red – green – blue • Additive Color System © 2016 Pearson Education, Inc., Hoboken, 4 NJ. All rights reserved. Additive Color System © 2016 Pearson Education, Inc., Hoboken, 5 NJ. All rights reserved. Additive Color System of RGB • Full intensities of red + green + blue = white • Full intensities of red + green = yellow • Full intensities of green + blue = cyan • Full intensities of red + blue = magenta • Zero intensities of red , green , and blue = black • Same intensities of red , green , and blue = some kind of gray © 2016 Pearson Education, Inc., Hoboken, 6 NJ. All rights reserved. Color Display From a standard CRT monitor screen © 2016 Pearson Education, Inc., Hoboken, 7 NJ. All rights reserved. Color Display From a SONY Trinitron monitor screen © 2016 Pearson Education, Inc., Hoboken, 8 NJ. -
Computational RYB Color Model and Its Applications
IIEEJ Transactions on Image Electronics and Visual Computing Vol.5 No.2 (2017) -- Special Issue on Application-Based Image Processing Technologies -- Computational RYB Color Model and its Applications Junichi SUGITA† (Member), Tokiichiro TAKAHASHI†† (Member) †Tokyo Healthcare University, ††Tokyo Denki University/UEI Research <Summary> The red-yellow-blue (RYB) color model is a subtractive model based on pigment color mixing and is widely used in art education. In the RYB color model, red, yellow, and blue are defined as the primary colors. In this study, we apply this model to computers by formulating a conversion between the red-green-blue (RGB) and RYB color spaces. In addition, we present a class of compositing methods in the RYB color space. Moreover, we prescribe the appropriate uses of these compo- siting methods in different situations. By using RYB color compositing, paint-like compositing can be easily achieved. We also verified the effectiveness of our proposed method by using several experiments and demonstrated its application on the basis of RYB color compositing. Keywords: RYB, RGB, CMY(K), color model, color space, color compositing man perception system and computer displays, most com- 1. Introduction puter applications use the red-green-blue (RGB) color mod- Most people have had the experience of creating an arbi- el3); however, this model is not comprehensible for many trary color by mixing different color pigments on a palette or people who not trained in the RGB color model because of a canvas. The red-yellow-blue (RYB) color model proposed its use of additive color mixing. As shown in Fig. -
Color Printing Techniques
4-H Photography Skill Guide Color Printing Techniques Enlarging Color Negatives Making your own color prints from Color Relations color negatives provides a whole new area of Before going ahead into this fascinating photography for you to enjoy. You can make subject of color printing, let’s make sure we prints nearly any size you want, from small ones understand some basic photographic color and to big enlargements. You can crop pictures for the visual relationships. composition that’s most pleasing to you. You can 1. White light (sunlight or the light from an control the lightness or darkness of the print, as enlarger lamp) is made up of three primary well as the color balance, and you can experiment colors: red, green, and blue. These colors are with control techniques to achieve just the effect known as additive primary colors. When you’re looking for. The possibilities for creating added together in approximately equal beautiful color prints are as great as your own amounts, they produce white light. imagination. You can print color negatives on conventional 2. Color‑negative film has a separate light‑ color printing paper. It’s the kind of paper your sensitive layer to correspond with each photofinisher uses. It requires precise processing of these three additive primary colors. in two or three chemical solutions and several Images recorded on these layers appear as washes in water. It can be processed in trays or a complementary (opposite) colors. drum processor. • A red subject records on the red‑sensitive layer as cyan (blue‑green). • A green subject records on the green‑ sensitive layer as magenta (blue‑red). -
Simplest Color Balance
Published in Image Processing On Line on 2011{10{24. Submitted on 2011{00{00, accepted on 2011{00{00. ISSN 2105{1232 c 2011 IPOL & the authors CC{BY{NC{SA This article is available online with supplementary materials, software, datasets and online demo at http://dx.doi.org/10.5201/ipol.2011.llmps-scb 2014/07/01 v0.5 IPOL article class Simplest Color Balance Nicolas Limare1, Jose-Luis Lisani2, Jean-Michel Morel1, Ana Bel´enPetro2, Catalina Sbert2 1 CMLA, ENS Cachan, France ([email protected], [email protected]) 2 TAMI, Universitat Illes Balears, Spain (fjoseluis.lisani, anabelen.petro, [email protected]) Abstract In this paper we present the simplest possible color balance algorithm. The assumption under- lying this algorithm is that the highest values of R, G, B observed in the image must correspond to white, and the lowest values to obscurity. The algorithm simply stretches, as much as it can, the values of the three channels Red, Green, Blue (R, G, B), so that they occupy the maximal possible range [0, 255] by applying an affine transform ax+b to each channel. Since many images contain a few aberrant pixels that already occupy the 0 and 255 values, the proposed method saturates a small percentage of the pixels with the highest values to 255 and a small percentage of the pixels with the lowest values to 0, before applying the affine transform. Source Code The source code (ANSI C), its documentation, and the online demo are accessible at the IPOL web page of this article1. -
Image Processing Based Automatic Color Inspection and Detection of Colored Wires in Electric Cables
International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 5 (2017) pp. 611-617 © Research India Publications. http://www.ripublication.com Image Processing based Automatic Color Inspection and Detection of Colored Wires in Electric Cables 1Rajalakshmi M, 2Ganapathy V, 3Rengaraj R and 4Rohit D 1Assistant Professor, 2Professor, Dept. of IT., SRM University, Kattankulathur-603203, Tamil Nadu, India. 3Associate Professor, Dept. of EEE, SSN College of Engg., Kalavakkam-603110, Tamil Nadu, India. 4Research Associate, Siechem Wires and Cables, Pondicherry, India. Abstract manipulation and interpretation of visual information, and it plays an increasingly important role in our daily life. Also it In this paper, an automatic visual inspection system using is applied in a variety of disciplines and fields in science and image processing techniques to check the consistency of technology. Some of the applications are television, color of the wire after insulation, and meeting the photography, robotics, remote sensing, medical diagnosis requirements of the manufacturer, is presented. Also any and industrial inspection. Probably the most powerful image color irregularities occurring across the insulation are processing system is the human brain together with the eye. displayed. The main contributions of this paper are: (i) the The system receives, enhances and stores images at self-learning system, which does not require manual enormous rates of speed. The objective of image processing intervention and (ii) a color detection algorithm that can be is to visually enhance or statistically evaluate some aspect of able to meet up with varied finishing of the wire insulation. an image not readily apparent in its original form. -
Arxiv:1902.00267V1 [Cs.CV] 1 Feb 2019 Fcmue Iin Oto H Aaesue O Mg Classificat Image Th for in Used Applications Datasets Fundamental the Most of the Most Vision
ColorNet: Investigating the importance of color spaces for image classification⋆ Shreyank N Gowda1 and Chun Yuan2 1 Computer Science Department, Tsinghua University, Beijing 10084, China [email protected] 2 Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China [email protected] Abstract. Image classification is a fundamental application in computer vision. Recently, deeper networks and highly connected networks have shown state of the art performance for image classification tasks. Most datasets these days consist of a finite number of color images. These color images are taken as input in the form of RGB images and clas- sification is done without modifying them. We explore the importance of color spaces and show that color spaces (essentially transformations of original RGB images) can significantly affect classification accuracy. Further, we show that certain classes of images are better represented in particular color spaces and for a dataset with a highly varying number of classes such as CIFAR and Imagenet, using a model that considers multi- ple color spaces within the same model gives excellent levels of accuracy. Also, we show that such a model, where the input is preprocessed into multiple color spaces simultaneously, needs far fewer parameters to ob- tain high accuracy for classification. For example, our model with 1.75M parameters significantly outperforms DenseNet 100-12 that has 12M pa- rameters and gives results comparable to Densenet-BC-190-40 that has 25.6M parameters for classification of four competitive image classifica- tion datasets namely: CIFAR-10, CIFAR-100, SVHN and Imagenet. Our model essentially takes an RGB image as input, simultaneously converts the image into 7 different color spaces and uses these as inputs to individ- ual densenets. -
Color Balance
TECHNOLOGY 3.2 – ADOBE® PHOTOSHOP® MINUTE7 STARTER Color Balance OBJECTIVES STEP 1 | LEARN By reviewing the Color Balance tutorial, students will learn how to modify the color balance of a photograph using Adobe® Photoshop®. STEP 2 | PRACTICE Students will use the Color Balance tutorial as a reference as they change the color balance of a photograph. Note: A practice photo is provided in the tutorial folder. STEP 3 | USE Students will apply knowledge when editing and reviewing photographs being published. 21ST CENTURY SKILLS Employment in the 21st century requires the ability to learn and use technology appropriately and effectively. Adobe Photoshop is an industry-standard software that allows for creative thinking. COMMON CORE ISTE STANDARDS ISTE STATE STANDARDS 1B: Create original works. ELA-Literacy.SL.9-12.5, CCRA.SL.5 6A: Understand and use technology systems. Make strategic use of digital media to 6B: Select and use applications effectively enhance understanding. and productively. 6C: Troubleshoot systems and applications. Do you have an idea for a 7-Minute Starter? Email us at [email protected] 14-0610 Color Balance Sometimes an image may have a slight color cast, either due to White Balance issues with the camera or simply because of artificial lighting indoors where the photo was taken. Color can be quickly neutralized by using Adobe® Photoshop’s® Auto Color feature located under the Image Tab. Auto Color adjusts the contrast and color of an image by searching the image to identify shadows, mid-tones and highlights. If the Auto Color tool doesn’t do the trick — the following method is an easy way to help remove the color cast from a photo using the Neutral Color Picker and may produce better results. -
Color Management Guide Printing with Epson Premium ICC Profiles Copyright Notice All Rights Reserved
Epson Professional Imaging Color Management Guide Printing With Epson Premium ICC Profiles Copyright Notice All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Seiko Epson Corporation. The information contained herein is designed only for use with this Epson product. Epson is not responsible for any use of this information as applied to other equipment. Neither Seiko Epson Corporation nor its affiliates shall be liable to the purchaser of this product or third parties for damages, losses, costs, or expenses incurred by purchaser or third parties as a result of: accident, misuse, or abuse of this product or unauthorized modifications, repairs, or alterations to this product, or (excluding the U.S.) failure to strictly comply with Seiko Epson Corporation’s operating and maintenance instructions. Seiko Epson Corporation shall not be liable for any damages or problems arising from the use of any options or any consumable products other than those designated as Original Epson Products or Epson Approved Products by Seiko Epson Corporation. Responsible Use of Copyrighted Materials Epson encourages each user to be responsible and respectful of the copyright laws when using any Epson product. While some countries’ laws permit limited copying or reuse of copyrighted material in certain circumstances, those circumstances may not be as broad as some people assume. Contact your legal advisor for any questions regarding copyright law. Trademarks Epson and Epson Stylus are registered trademarks, and Epson Exceed Your Vision is a registered logomark of Seiko Epson Corporation.