Color and Color Models

Size: px
Start display at page:

Download "Color and Color Models"

Transcription

1 Einführung in Visual Computing Color and Color Models Werner Purgathofer Color problem specification light and perception colorimetry device color systems color ordering systems color symbolism Werner Purgathofer 1 1

2 Color - Why Do We Care? Computer Graphics is all about the generation and the manipulation of color images proper understanding and handling of color is necessary at every step Werner Purgathofer 2 What is Light? light = narrow frequency band of electromagnetic spectrum red border: 380 THz 780 nm violet border: 780 THz 380 nm AM radio FM radio an nd TV icrowaves m frared inf visible traviolet ult X- -rays (nm) wavelength frequency (Hz) Werner Purgathofer 3 2

3 Light - An Electromagnetic Wave light is electromagnetic energy monochrome light can be described either by frequency f or wavelength c = f (c = speed of light) shorter wavelength equals higher frequency red 700 nm violet 400 nm E Werner Purgathofer 4 t Light Spectrum normally, a ray of light contains many different waves with individual frequencies the associated distribution of wavelength intensities per wavelength is referred to as the spectrum of a given ray or light source Werner Purgathofer 5 3

4 Dominant Wavelength Frequency energy white light energy greenish light E D E W wavelength wavelength 400 nm 700 nm dominant wavelength dominant wavelength frequency (hue, color) brightness (area under the curve) purity E E E D...dominant energy density Werner Purgathofer 6 D E D W E W...white light energy density The Human Eye aqueous [Augenkammer] lens cornea [Hornhaut] iris [Regenbogen- haut] retina contains rods: b/w cones: color retina [Netzhaut] vitreous humor [Glaskörper] optical axis visual axis optic disc [Papille] fovea nerve macula lutea [gelber Fleck] Werner Purgathofer 7 rods cones 4

5 The Human Eye 3 types of cones different wavelength sensitivities: red green blue fraction of absorbed light 16% 8% 4% 2% 1% λ Werner Purgathofer 8 Color Blindness red/green blindness red & green cones too similar fraction of absorbed light 16% 8% 4% 2% 1% λ Werner Purgathofer 9 5

6 Color Blindness red/green blindness red & green cones too similar blue blindness other no blue cones cones missing cones too similar fraction of absorbed light 16% 8% 4% 2% 1% λ Werner Purgathofer 10 Color Blindness Tests 5 = normal nothing = red/green blind 2 = red/green weak nothing = normal Werner Purgathofer 11 6

7 Color Blindness Tests 8 = normal 3 = red/green weak nothing = r/g blind 8 = red/green blind 12 = blue/yellow blind 182 = normal Werner Purgathofer 12 Color Spaces (CS) Color Metric Spaces (CIE XYZ, L*a*b*) used to measure absolute values and differences - roots in colorimetry Device Color Spaces (RGB, CMY, CMYK) used in conjunction with device Color Ordering Spaces (HSV, HLS) used to find colors according to some criterion the distinction between them is somewhat obscured by the prevalence of multi-purpose RGB in computer graphics Werner Purgathofer 13 7

8 What is our Goal? to be able to quantify color in a meaningful, expressive, consistent and reproducible way. problem: color is a perceived quantity, not a direct, physical observable Werner Purgathofer 14 Color - A Visual Sensation object light stimulus eye nerve signal brain electromagnetic rays realm of direct observables color sensation realm of psychology Werner Purgathofer 15 8

9 Colorimetry CM is the branch of color science concerned with numerically specifying the color of a physically defined visual stimulus in such manner that stimuli with the same specification look alike under the same viewing conditions stimuli that look alike have the same specification the numbers used are continuous functions of the physical parameters Werner Purgathofer 16 Colorimetry Properties Colorimetry only considers the visual discriminability of physical beams of radiation for the purposes of Colorimetry a color is an equivalence class of mutually indiscriminable beams colors in this sense cannot be said to be red, green or any other color name discriminability is decided before the brain - Colorimetry is not psychology Werner Purgathofer 17 9

10 Color Matching Experiments observers had to match monochromatic test lights by combining 3 fixed primaries test test R+G+B green goal: find the unique RGB coordinates for each stimulus Werner Purgathofer 18 Color Matching Experiments observers had to match monochromatic test lights by combining 3 fixed primaries R = nm G = nm B = nm viewer controls independently variable primary sources viewing screen test source masking screen Werner Purgathofer 19 10

11 Tristimulus Values the values R Q, G Q and B Q of a stimulus Q that fulfill test test R+G+B green Q R Q R G Q G B Q B are called the tristimulus values of Q in the case of a monochromatic stimulus Q, the values R, G and B are called the spectral tristimulus values Werner Purgathofer 20 Color Matching Procedure (1) test field = 700 nm-red with radiance P ref observer adjusts luminance of R (G=0, B=0) (2) test light wavelength is decreased in constant steps (radiance P ref stays the same) observer adjusts R, G, B (3) repeat for entire visible range Werner Purgathofer nm 11

12 Color Matching Result!? 100 no match possible!?!? nm observers want to subtract red light from the match side...!? Werner Purgathofer 22 Color Matching Experiment Problem for some colors observers want to reduce red light to negative values!? but there is no negative light! test test t R+ +G+B green? Werner Purgathofer 23 12

13 Negative Light in a Color Matching Exp. if a match using only positive RGB values proved impossible, observers could simulate a subtraction of red from the match side by adding it to the test side test tes st + R G+B green Werner Purgathofer 24 CIE RGB Color Matching Functions 100 b(λ) g(λ) r(λ) 0? nm nm nm nm Werner Purgathofer 25 13

14 CIE XYZ problem solution: XYZ color system tristimulus system derived from RGB based on 3 imaginaryi primaries i all 3 primaries are imaginary colors only positive XYZ values can occur! 1931 by CIE (Commission Internationale de l Eclairage) Werner Purgathofer 26 Y Z X RGB vs. XYZ negative component disappears y( ) is the achromatic luminance sensitivity RGB system XYZ system b(λ) r(λ) g(λ) 1 z(λ) y(λ) x(λ) nm nm amounts of RGB primaries needed to display spectral colors Werner Purgathofer 27 amounts of CIE primaries needed to display spectral colors 14

15 CIE Color Model Formulas XYZ color model C( ) = XX + YY + ZZ (X, Y, Z are primaries) normalized chromaticity values x, y X x X Y Z ( z = 1 x y ) Y y X Y Z Y 1 complete description of color: x, y, Y Werner Purgathofer 28 1 Z 1 X CIE Chromaticity Diagram spectral colors identifying complementary colors determining dominant wavelength, purity comparing color gamuts purple line spectral color positions are along the boundary curve Werner Purgathofer 29 15

16 Properties of CIE Diagram (2) C 1 representing complementary colors on the chromaticity diagram C C 2 Werner Purgathofer 30 Properties of CIE Diagram (3) C sp C s determining dominant wavelength and purity with the chromaticity diagram C 1 C C 2 Cp C 1 C s C 2 C p? complement C sp Werner Purgathofer 31 16

17 Color Spaces (CS) Color Metric Spaces (CIE XYZ, L*a*b) used to measure absolute values and differences - roots in colorimetry Device Color Spaces (RGB, CMY, CMYK) used in conjunction with device Color Ordering Spaces (HSV, HLS) used to find colors according to some criterion the distinction between them is somewhat obscured by the prevalence of multi-purpose RGB in computer graphics Werner Purgathofer 32 RGB Color Model cyan (0,1,1) blue (0,0,1) green (0,1,0) black (0,0,0) white (1,1,1) magenta (1,0,1) yellow (1,1,0) red (1,0,0) primary colors red, green, blue additive color model (for monitors) Werner Purgathofer 33 C( ) = RR + GG + BB 17

18 RGB Color Model Images 3 views of the RGB color cube Werner Purgathofer 34 Gamuts of RGB Monitors monitor gamuts can be very different no monitor can display all colors Werner Purgathofer 35 18

19 CMY Color Model magenta (0,1,0) blue (1,1,0) red (011) (0,1,1) black (1,1,1) yellow (0,0,1) white (0,0,0) green (1,0,1) cyan (1,0,0) Werner Purgathofer 36 primary colors cyan, magenta, yellow subtractive color model (for hardcopy devices) C=G+B, using C subtracts R C 1 R M 1 G Y 1 B CMY Color Model Images 3 views of the CMY color cube Werner Purgathofer 37 19

20 Gamuts of CMY(K) Printers printer gamuts can be very different no printer can display all colors Werner Purgathofer 38 Color Spaces (CS) Color Metric Spaces (CIE XYZ, L*a*b) used to measure absolute values and differences - roots in colorimetry Device Color Spaces (RGB, CMY, CMYK) used in conjunction with device Color Ordering Spaces (HSV, HLS) used to find colors according to some criterion the distinction between them is somewhat obscured by the prevalence of multi-purpose RGB in computer graphics Werner Purgathofer 39 20

21 Colour Ordering Systems (COS) primary aim: enable the user to intuitively choose colour values according to certain criteria choice can yield single or multiple colour values examples: HSV, HLS, Munsell, NCS, RAL Design, Coloroid used in bottom-up parts of a design process sometimes physical samples are provided Werner Purgathofer 40 HSV Color Model more intuitive color specification derived from the RGB color model: when the RGB color cube is viewed along the diagonal from white to black, the color cube outline is a hexagon RGB Color Cube Werner Purgathofer 41 Color Hexagon 21

22 HSV Color Model Hexcone color components: hue (H) [0, 360 ] saturation (S) [0, 1] value (V) [0, 1] HSV hexcone Werner Purgathofer 42 HSV Color Model Hexcone color components: hue (H) [0, 360 ] saturation (S) [0, 1] value (V) [0, 1] HSV hexcone Werner Purgathofer 43 22

23 HSV Color Definition color definition select hue, S=1, V=1 add black pigments, pg i.e., decrease V add white pigments, i.e., decrease S Shades cross section of the HSV hexcone showing regions for shades, tints, and tones Werner Purgathofer 44 S HLS Color Model color components: hue (H) [0, 360 ] lightness (L) [0, 1] saturation (S) [0, 1] HLS double cone Werner Purgathofer 45 23

24 Color Model Summary Colorimetry: CIE XYZ: contains all visible colours Device Color Systems: RGB: additive device color space (monitors) CMY(K): subtractive device color space (printers) YIQ: television (NTSC) (Y=luminance, I=R-Y, Q=B-Y) Color Ordering Systems: HSV, HLS: for user interfaces Werner Purgathofer 46 Color Symbolism: Some Aspects 6 to 11 basic colors categories, hierarchies dependentd on context t / application large variation in use what is red? what is blue? what is white?! Werner Purgathofer 47 24

25 Color in Religion Islam: green Buddhism: yellow, orange, red & purple Hinduism: orange, blue & blue-violet Christs: liturgical colors without theological connex Werner Purgathofer 48 Political Symbol Colors parties revolutions / movements flags Werner Purgathofer 49 25

26 Color Labeling at home water pipes electrical wires traffic... waste separation traffic signs traffic lights parking concepts public transport Werner Purgathofer 50 Color Labeling technology resistors thermochrome colors nature courtship [Balz] warning colors protective mimicry [Tarnfarben] Werner Purgathofer 51 26

27 Color Effect: BLUE distance faithfulness, loyality desire phantasy male devine peace cold Werner Purgathofer 52 Color Effect: RED blood energy love female rich, noble labor movement warm corrections Werner Purgathofer 53 27

28 Color Effect: GREEN profit young love hope prematurity, unripe poison nature neutral environment protection Werner Purgathofer 54 Color Effect: YELLOW sun optimism enlightenment t jealousy [Neid] stinginess [Geiz] warning color warm Werner Purgathofer 55 28

29 Color Effect: BLACK end, death sadness negative emotions bad luck elegance emptiness cold Werner Purgathofer 56 Einführung in Visual Computing Color and Color Models The End 29

Werner Purgathofer

Werner Purgathofer Einführung in Visual Computing 186.822 Color and Color Models Werner Purgathofer Color problem specification light and perceptionp colorimetry device color systems color ordering systems color symbolism

More information

COLOR. and the human response to light

COLOR. and the human response to light COLOR and the human response to light Contents Introduction: The nature of light The physiology of human vision Color Spaces: Linear Artistic View Standard Distances between colors Color in the TV 2 Amazing

More information

COLOR and the human response to light

COLOR and the human response to light COLOR and the human response to light Contents Introduction: The nature of light The physiology of human vision Color Spaces: Linear Artistic View Standard Distances between colors Color in the TV 2 How

More information

Color & Graphics. Color & Vision. The complete display system is: We'll talk about: Model Frame Buffer Screen Eye Brain

Color & Graphics. Color & Vision. The complete display system is: We'll talk about: Model Frame Buffer Screen Eye Brain Color & Graphics The complete display system is: Model Frame Buffer Screen Eye Brain Color & Vision We'll talk about: Light Visions Psychophysics, Colorimetry Color Perceptually based models Hardware models

More information

To discuss. Color Science Color Models in image. Computer Graphics 2

To discuss. Color Science Color Models in image. Computer Graphics 2 Color To discuss Color Science Color Models in image Computer Graphics 2 Color Science Light & Spectra Light is an electromagnetic wave It s color is characterized by its wavelength Laser consists of single

More information

Light. intensity wavelength. Light is electromagnetic waves Laser is light that contains only a narrow spectrum of frequencies

Light. intensity wavelength. Light is electromagnetic waves Laser is light that contains only a narrow spectrum of frequencies Image formation World, image, eye Light Light is electromagnetic waves Laser is light that contains only a narrow spectrum of frequencies intensity wavelength Visible light is light with wavelength from

More information

Digital Image Processing Color Models &Processing

Digital Image Processing Color Models &Processing Digital Image Processing Color Models &Processing Dr. Hatem Elaydi Electrical Engineering Department Islamic University of Gaza Fall 2015 Nov 16, 2015 Color interpretation Color spectrum vs. electromagnetic

More information

Image and video processing (EBU723U) Colour Images. Dr. Yi-Zhe Song

Image and video processing (EBU723U) Colour Images. Dr. Yi-Zhe Song Image and video processing () Colour Images Dr. Yi-Zhe Song yizhe.song@qmul.ac.uk Today s agenda Colour spaces Colour images PGM/PPM images Today s agenda Colour spaces Colour images PGM/PPM images History

More information

Colors in Images & Video

Colors in Images & Video LECTURE 8 Colors in Images & Video CS 5513 Multimedia Systems Spring 2009 Imran Ihsan Principal Design Consultant OPUSVII www.opuseven.com Faculty of Engineering & Applied Sciences 1. Light and Spectra

More information

The Principles of Chromatics

The Principles of Chromatics The Principles of Chromatics 03/20/07 2 Light Electromagnetic radiation, that produces a sight perception when being hit directly in the eye The wavelength of visible light is 400-700 nm 1 03/20/07 3 Visible

More information

Color Image Processing

Color Image Processing Color Image Processing Jesus J. Caban Outline Discuss Assignment #1 Project Proposal Color Perception & Analysis 1 Discuss Assignment #1 Project Proposal Due next Monday, Oct 4th Project proposal Submit

More information

Raster Graphics. Overview קורס גרפיקה ממוחשבת 2008 סמסטר ב' What is an image? What is an image? Image Acquisition. Image display 5/19/2008.

Raster Graphics. Overview קורס גרפיקה ממוחשבת 2008 סמסטר ב' What is an image? What is an image? Image Acquisition. Image display 5/19/2008. Overview Images What is an image? How are images displayed? Color models How do we perceive colors? How can we describe and represent colors? קורס גרפיקה ממוחשבת 2008 סמסטר ב' Raster Graphics 1 חלק מהשקפים

More information

קורס גרפיקה ממוחשבת 2008 סמסטר ב' Raster Graphics 1 חלק מהשקפים מעובדים משקפים של פרדו דוראנד, טומס פנקהאוסר ודניאל כהן-אור

קורס גרפיקה ממוחשבת 2008 סמסטר ב' Raster Graphics 1 חלק מהשקפים מעובדים משקפים של פרדו דוראנד, טומס פנקהאוסר ודניאל כהן-אור קורס גרפיקה ממוחשבת 2008 סמסטר ב' Raster Graphics 1 חלק מהשקפים מעובדים משקפים של פרדו דוראנד, טומס פנקהאוסר ודניאל כהן-אור Images What is an image? How are images displayed? Color models Overview How

More information

Color Science. CS 4620 Lecture 15

Color Science. CS 4620 Lecture 15 Color Science CS 4620 Lecture 15 2013 Steve Marschner 1 [source unknown] 2013 Steve Marschner 2 What light is Light is electromagnetic radiation exists as oscillations of different frequency (or, wavelength)

More information

COLOR. Elements of color. Visible spectrum. The Fovea. Lecture 3 October 30, Ingela Nyström 1. There are three types of cones, S, M and L

COLOR. Elements of color. Visible spectrum. The Fovea. Lecture 3 October 30, Ingela Nyström 1. There are three types of cones, S, M and L COLOR Elements of color Angel 1.4, 2.4, 7.12 J. Lindblad 2001-11-01 Color = The eye s and the brain s impression of electromagnetic radiation in the visual spectra. How is color perceived? Visible spectrum

More information

Color Image Processing. Gonzales & Woods: Chapter 6

Color Image Processing. Gonzales & Woods: Chapter 6 Color Image Processing Gonzales & Woods: Chapter 6 Objectives What are the most important concepts and terms related to color perception? What are the main color models used to represent and quantify color?

More information

the eye Light is electromagnetic radiation. The different wavelengths of the (to humans) visible part of the spectra make up the colors.

the eye Light is electromagnetic radiation. The different wavelengths of the (to humans) visible part of the spectra make up the colors. Computer Assisted Image Analysis TF 3p and MN1 5p Color Image Processing Lecture 14 GW 6 (suggested problem 6.25) How does the human eye perceive color? How can color be described using mathematics? Different

More information

Multimedia Systems and Technologies

Multimedia Systems and Technologies Multimedia Systems and Technologies Faculty of Engineering Master s s degree in Computer Engineering Marco Porta Computer Vision & Multimedia Lab Dipartimento di Ingegneria Industriale e dell Informazione

More information

Achim J. Lilienthal Mobile Robotics and Olfaction Lab, AASS, Örebro University

Achim J. Lilienthal Mobile Robotics and Olfaction Lab, AASS, Örebro University Achim J. Lilienthal Mobile Robotics and Olfaction Lab, Room T1227, Mo, 11-12 o'clock AASS, Örebro University (please drop me an email in advance) achim.lilienthal@oru.se 1 2. General Introduction Schedule

More information

IFT3355: Infographie Couleur. Victor Ostromoukhov, Pierre Poulin Dép. I.R.O. Université de Montréal

IFT3355: Infographie Couleur. Victor Ostromoukhov, Pierre Poulin Dép. I.R.O. Université de Montréal IFT3355: Infographie Couleur Victor Ostromoukhov, Pierre Poulin Dép. I.R.O. Université de Montréal Color Appearance Visual Range Electromagnetic waves (in nanometres) γ rays X rays ultraviolet violet

More information

LECTURE 07 COLORS IN IMAGES & VIDEO

LECTURE 07 COLORS IN IMAGES & VIDEO MULTIMEDIA TECHNOLOGIES LECTURE 07 COLORS IN IMAGES & VIDEO IMRAN IHSAN ASSISTANT PROFESSOR LIGHT AND SPECTRA Visible light is an electromagnetic wave in the 400nm 700 nm range. The eye is basically similar

More information

For a long time I limited myself to one color as a form of discipline. Pablo Picasso. Color Image Processing

For a long time I limited myself to one color as a form of discipline. Pablo Picasso. Color Image Processing For a long time I limited myself to one color as a form of discipline. Pablo Picasso Color Image Processing 1 Preview Motive - Color is a powerful descriptor that often simplifies object identification

More information

COLOR. Elements of color. Visible spectrum. The Human Visual System. The Fovea. There are three types of cones, S, M and L. r( λ)

COLOR. Elements of color. Visible spectrum. The Human Visual System. The Fovea. There are three types of cones, S, M and L. r( λ) COLOR Elements of color Angel, 4th ed. 1, 2.5, 7.13 excerpt from Joakim Lindblad Color = The eye s and the brain s impression of electromagnetic radiation in the visual spectra How is color perceived?

More information

Color Science. What light is. Measuring light. CS 4620 Lecture 15. Salient property is the spectral power distribution (SPD)

Color Science. What light is. Measuring light. CS 4620 Lecture 15. Salient property is the spectral power distribution (SPD) Color Science CS 4620 Lecture 15 1 2 What light is Measuring light Light is electromagnetic radiation Salient property is the spectral power distribution (SPD) [Lawrence Berkeley Lab / MicroWorlds] exists

More information

Lecture Color Image Processing. by Shahid Farid

Lecture Color Image Processing. by Shahid Farid Lecture Color Image Processing by Shahid Farid What is color? Why colors? How we see objects? Photometry, Radiometry and Colorimetry Color measurement Chromaticity diagram Shahid Farid, PUCIT 2 Color or

More information

Digital Image Processing. Lecture # 8 Color Processing

Digital Image Processing. Lecture # 8 Color Processing Digital Image Processing Lecture # 8 Color Processing 1 COLOR IMAGE PROCESSING COLOR IMAGE PROCESSING Color Importance Color is an excellent descriptor Suitable for object Identification and Extraction

More information

Understand brightness, intensity, eye characteristics, and gamma correction, halftone technology, Understand general usage of color

Understand brightness, intensity, eye characteristics, and gamma correction, halftone technology, Understand general usage of color Understand brightness, intensity, eye characteristics, and gamma correction, halftone technology, Understand general usage of color 1 ACHROMATIC LIGHT (Grayscale) Quantity of light physics sense of energy

More information

12 Color Models and Color Applications. Chapter 12. Color Models and Color Applications. Department of Computer Science and Engineering 12-1

12 Color Models and Color Applications. Chapter 12. Color Models and Color Applications. Department of Computer Science and Engineering 12-1 Chapter 12 Color Models and Color Applications 12-1 12.1 Overview Color plays a significant role in achieving realistic computer graphic renderings. This chapter describes the quantitative aspects of color,

More information

Colorimetry and Color Modeling

Colorimetry and Color Modeling Color Matching Experiments 1 Colorimetry and Color Modeling Colorimetry is the science of measuring color. Color modeling, for the purposes of this Field Guide, is defined as the mathematical constructs

More information

Colour. Cunliffe & Elliott, Chapter 8 Chapman & Chapman, Digital Multimedia, Chapter 5. Autumn 2016 University of Stirling

Colour. Cunliffe & Elliott, Chapter 8 Chapman & Chapman, Digital Multimedia, Chapter 5. Autumn 2016 University of Stirling CSCU9N5: Multimedia and HCI 1 Colour What is colour? Human-centric view of colour Computer-centric view of colour Colour models Monitor production of colour Accurate colour reproduction Cunliffe & Elliott,

More information

Colour. Why/How do we perceive colours? Electromagnetic Spectrum (1: visible is very small part 2: not all colours are present in the rainbow!

Colour. Why/How do we perceive colours? Electromagnetic Spectrum (1: visible is very small part 2: not all colours are present in the rainbow! Colour What is colour? Human-centric view of colour Computer-centric view of colour Colour models Monitor production of colour Accurate colour reproduction Colour Lecture (2 lectures)! Richardson, Chapter

More information

Multimedia Systems Color Space Mahdi Amiri March 2012 Sharif University of Technology

Multimedia Systems Color Space Mahdi Amiri March 2012 Sharif University of Technology Course Presentation Multimedia Systems Color Space Mahdi Amiri March 2012 Sharif University of Technology Physics of Color Light Light or visible light is the portion of electromagnetic radiation that

More information

Color Image Processing. Jen-Chang Liu, Spring 2006

Color Image Processing. Jen-Chang Liu, Spring 2006 Color Image Processing Jen-Chang Liu, Spring 2006 For a long time I limited myself to one color as a form of discipline. Pablo Picasso It is only after years of preparation that the young artist should

More information

Image Processing for Mechatronics Engineering For senior undergraduate students Academic Year 2017/2018, Winter Semester

Image Processing for Mechatronics Engineering For senior undergraduate students Academic Year 2017/2018, Winter Semester Image Processing for Mechatronics Engineering For senior undergraduate students Academic Year 2017/2018, Winter Semester Lecture 8: Color Image Processing 04.11.2017 Dr. Mohammed Abdel-Megeed Salem Media

More information

Digital Image Processing COSC 6380/4393. Lecture 20 Oct 25 th, 2018 Pranav Mantini

Digital Image Processing COSC 6380/4393. Lecture 20 Oct 25 th, 2018 Pranav Mantini Digital Image Processing COSC 6380/4393 Lecture 20 Oct 25 th, 2018 Pranav Mantini What is color? Color is a psychological property of our visual experiences when we look at objects and lights, not a physical

More information

Color and Color Model. Chap. 12 Intro. to Computer Graphics, Spring 2009, Y. G. Shin

Color and Color Model. Chap. 12 Intro. to Computer Graphics, Spring 2009, Y. G. Shin Color and Color Model Chap. 12 Intro. to Computer Graphics, Spring 2009, Y. G. Shin Color Interpretation of color is a psychophysiology problem We could not fully understand the mechanism Physical characteristics

More information

CS 565 Computer Vision. Nazar Khan PUCIT Lecture 4: Colour

CS 565 Computer Vision. Nazar Khan PUCIT Lecture 4: Colour CS 565 Computer Vision Nazar Khan PUCIT Lecture 4: Colour Topics to be covered Motivation for Studying Colour Physical Background Biological Background Technical Colour Spaces Motivation Colour science

More information

Colour. Electromagnetic Spectrum (1: visible is very small part 2: not all colours are present in the rainbow!) Colour Lecture!

Colour. Electromagnetic Spectrum (1: visible is very small part 2: not all colours are present in the rainbow!) Colour Lecture! Colour Lecture! ITNP80: Multimedia 1 Colour What is colour? Human-centric view of colour Computer-centric view of colour Colour models Monitor production of colour Accurate colour reproduction Richardson,

More information

University of British Columbia CPSC 314 Computer Graphics Jan-Apr Tamara Munzner. Color.

University of British Columbia CPSC 314 Computer Graphics Jan-Apr Tamara Munzner. Color. University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2016 Tamara Munzner Color http://www.ugrad.cs.ubc.ca/~cs314/vjan2016 Vision/Color 2 RGB Color triple (r, g, b) represents colors with amount

More information

CIE tri-stimulus experiment. Color Value Functions. CIE 1931 Standard. Color. Diagram. Color light intensity for visual color match

CIE tri-stimulus experiment. Color Value Functions. CIE 1931 Standard. Color. Diagram. Color light intensity for visual color match CIE tri-stimulus experiment diffuse reflecting screen diffuse reflecting screen 770 769 768 test light 382 381 380 observer test light 445 535 630 445 535 630 observer light intensity for visual color

More information

Bettina Selig. Centre for Image Analysis. Swedish University of Agricultural Sciences Uppsala University

Bettina Selig. Centre for Image Analysis. Swedish University of Agricultural Sciences Uppsala University 2011-10-26 Bettina Selig Centre for Image Analysis Swedish University of Agricultural Sciences Uppsala University 2 Electromagnetic Radiation Illumination - Reflection - Detection The Human Eye Digital

More information

Color Image Processing

Color Image Processing Color Image Processing Selim Aksoy Department of Computer Engineering Bilkent University saksoy@cs.bilkent.edu.tr Color Used heavily in human vision. Visible spectrum for humans is 400 nm (blue) to 700

More information

Fig Color spectrum seen by passing white light through a prism.

Fig Color spectrum seen by passing white light through a prism. 1. Explain about color fundamentals. Color of an object is determined by the nature of the light reflected from it. When a beam of sunlight passes through a glass prism, the emerging beam of light is not

More information

Visual Perception. Overview. The Eye. Information Processing by Human Observer

Visual Perception. Overview. The Eye. Information Processing by Human Observer Visual Perception Spring 06 Instructor: K. J. Ray Liu ECE Department, Univ. of Maryland, College Park Overview Last Class Introduction to DIP/DVP applications and examples Image as a function Concepts

More information

Reading. Foley, Computer graphics, Chapter 13. Optional. Color. Brian Wandell. Foundations of Vision. Sinauer Associates, Sunderland, MA 1995.

Reading. Foley, Computer graphics, Chapter 13. Optional. Color. Brian Wandell. Foundations of Vision. Sinauer Associates, Sunderland, MA 1995. Reading Foley, Computer graphics, Chapter 13. Color Optional Brian Wandell. Foundations of Vision. Sinauer Associates, Sunderland, MA 1995. Gerald S. Wasserman. Color Vision: An Historical ntroduction.

More information

Reading for Color. Vision/Color. RGB Color. Vision/Color. University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2013.

Reading for Color. Vision/Color. RGB Color. Vision/Color. University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2013. University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2013 Tamara Munzner Vision/Color Reading for Color RB Chap Color FCG Sections 3.2-3.3 FCG Chap 20 Color FCG Chap 21.2.2 Visual Perception

More information

Chapter 3 Part 2 Color image processing

Chapter 3 Part 2 Color image processing Chapter 3 Part 2 Color image processing Motivation Color fundamentals Color models Pseudocolor image processing Full-color image processing: Component-wise Vector-based Recent and current work Spring 2002

More information

6 Color Image Processing

6 Color Image Processing 6 Color Image Processing Angela Chih-Wei Tang ( 唐之瑋 ) Department of Communication Engineering National Central University JhongLi, Taiwan 2009 Fall Outline Color fundamentals Color models Pseudocolor image

More information

EECS490: Digital Image Processing. Lecture #12

EECS490: Digital Image Processing. Lecture #12 Lecture #12 Image Correlation (example) Color basics (Chapter 6) The Chromaticity Diagram Color Images RGB Color Cube Color spaces Pseudocolor Multispectral Imaging White Light A prism splits white light

More information

Mahdi Amiri. March Sharif University of Technology

Mahdi Amiri. March Sharif University of Technology Course Presentation Multimedia Systems Color Space Mahdi Amiri March 2014 Sharif University of Technology The wavelength λ of a sinusoidal waveform traveling at constant speed ν is given by Physics of

More information

Color and Perception. CS535 Fall Daniel G. Aliaga Department of Computer Science Purdue University

Color and Perception. CS535 Fall Daniel G. Aliaga Department of Computer Science Purdue University Color and Perception CS535 Fall 2014 Daniel G. Aliaga Department of Computer Science Purdue University Elements of Color Perception 2 Elements of Color Physics: Illumination Electromagnetic spectra; approx.

More information

PERCEIVING COLOR. Functions of Color Vision

PERCEIVING COLOR. Functions of Color Vision PERCEIVING COLOR Functions of Color Vision Object identification Evolution : Identify fruits in trees Perceptual organization Add beauty to life Slide 2 Visible Light Spectrum Slide 3 Color is due to..

More information

Lecture 8. Color Image Processing

Lecture 8. Color Image Processing Lecture 8. Color Image Processing EL512 Image Processing Dr. Zhu Liu zliu@research.att.com Note: Part of the materials in the slides are from Gonzalez s Digital Image Processing and Onur s lecture slides

More information

Comparing Sound and Light. Light and Color. More complicated light. Seeing colors. Rods and cones

Comparing Sound and Light. Light and Color. More complicated light. Seeing colors. Rods and cones Light and Color Eye perceives EM radiation of different wavelengths as different colors. Sensitive only to the range 4nm - 7 nm This is a narrow piece of the entire electromagnetic spectrum. Comparing

More information

Colors in images. Color spaces, perception, mixing, printing, manipulating...

Colors in images. Color spaces, perception, mixing, printing, manipulating... Colors in images Color spaces, perception, mixing, printing, manipulating... Tomáš Svoboda Czech Technical University, Faculty of Electrical Engineering Center for Machine Perception, Prague, Czech Republic

More information

Figure 1: Energy Distributions for light

Figure 1: Energy Distributions for light Lecture 4: Colour The physical description of colour Colour vision is a very complicated biological and psychological phenomenon. It can be described in many different ways, including by physics, by subjective

More information

Digital Image Processing (DIP)

Digital Image Processing (DIP) University of Kurdistan Digital Image Processing (DIP) Lecture 6: Color Image Processing Instructor: Kaveh Mollazade, Ph.D. Department of Biosystems Engineering, Faculty of Agriculture, University of Kurdistan,

More information

Color vision and representation

Color vision and representation Color vision and representation S M L 0.0 0.44 0.52 Mark Rzchowski Physics Department 1 Eye perceives different wavelengths as different colors. Sensitive only to 400nm - 700 nm range Narrow piece of the

More information

Introduction to computer vision. Image Color Conversion. CIE Chromaticity Diagram and Color Gamut. Color Models

Introduction to computer vision. Image Color Conversion. CIE Chromaticity Diagram and Color Gamut. Color Models Introduction to computer vision In general, computer vision covers very wide area of issues concerning understanding of images by computers. It may be considered as a part of artificial intelligence and

More information

Unit 8: Color Image Processing

Unit 8: Color Image Processing Unit 8: Color Image Processing Colour Fundamentals In 666 Sir Isaac Newton discovered that when a beam of sunlight passes through a glass prism, the emerging beam is split into a spectrum of colours The

More information

Lecture 3: Grey and Color Image Processing

Lecture 3: Grey and Color Image Processing I22: Digital Image processing Lecture 3: Grey and Color Image Processing Prof. YingLi Tian Sept. 13, 217 Department of Electrical Engineering The City College of New York The City University of New York

More information

Color images C1 C2 C3

Color images C1 C2 C3 Color imaging Color images C1 C2 C3 Each colored pixel corresponds to a vector of three values {C1,C2,C3} The characteristics of the components depend on the chosen colorspace (RGB, YUV, CIELab,..) Digital

More information

Digital Image Processing

Digital Image Processing Digital Image Processing Color Image Processing Christophoros Nikou cnikou@cs.uoi.gr University of Ioannina - Department of Computer Science and Engineering 2 Color Image Processing It is only after years

More information

Introduction & Colour

Introduction & Colour Introduction & Colour Eric C. McCreath School of Computer Science The Australian National University ACT 0200 Australia ericm@cs.anu.edu.au Overview 2 Computer Graphics Uses (Chapter 1) Basic Hardware

More information

Wireless Communication

Wireless Communication Wireless Communication Systems @CS.NCTU Lecture 4: Color Instructor: Kate Ching-Ju Lin ( 林靖茹 ) Chap. 4 of Fundamentals of Multimedia Some reference from http://media.ee.ntu.edu.tw/courses/dvt/15f/ 1 Outline

More information

Color Image Processing EEE 6209 Digital Image Processing. Outline

Color Image Processing EEE 6209 Digital Image Processing. Outline Outline Color Image Processing Motivation and Color Fundamentals Standard Color Models (RGB/CMYK/HSI) Demosaicing and Color Filtering Pseudo-color and Full-color Image Processing Color Transformation Tone

More information

Digital Image Processing

Digital Image Processing Digital Image Processing 6. Color Image Processing Computer Engineering, Sejong University Category of Color Processing Algorithm Full-color processing Using Full color sensor, it can obtain the image

More information

Introduction. The Spectral Basis for Color

Introduction. The Spectral Basis for Color Introduction Color is an extremely important part of most visualizations. Choosing good colors for your visualizations involves understanding their properties and the perceptual characteristics of human

More information

Color. Fredo Durand Many slides by Victor Ostromoukhov. Color Vision 1

Color. Fredo Durand Many slides by Victor Ostromoukhov. Color Vision 1 Color Fredo Durand Many slides by Victor Ostromoukhov Color Vision 1 Today: color Disclaimer: Color is both quite simple and quite complex There are two options to teach color: pretend it all makes sense

More information

19. Vision and color

19. Vision and color 19. Vision and color 1 Reading Glassner, Principles of Digital Image Synthesis, pp. 5-32. Watt, Chapter 15. Brian Wandell. Foundations of Vision. Sinauer Associates, Sunderland, MA, pp. 45-50 and 69-97,

More information

Color Theory: Defining Brown

Color Theory: Defining Brown Color Theory: Defining Brown Defining Colors Colors can be defined in many different ways. Computer users are often familiar with colors defined as percentages or amounts of red, green, and blue (RGB).

More information

Color Perception. Color, What is It Good For? G Perception October 5, 2009 Maloney. perceptual organization. perceptual organization

Color Perception. Color, What is It Good For? G Perception October 5, 2009 Maloney. perceptual organization. perceptual organization G892223 Perception October 5, 2009 Maloney Color Perception Color What s it good for? Acknowledgments (slides) David Brainard David Heeger perceptual organization perceptual organization 1 signaling ripeness

More information

University of British Columbia CPSC 414 Computer Graphics

University of British Columbia CPSC 414 Computer Graphics University of British Columbia CPSC 414 Computer Graphics Color 2 Week 10, Fri 7 Nov 2003 Tamara Munzner 1 Readings Chapter 1.4: color plus supplemental reading: A Survey of Color for Computer Graphics,

More information

IMAGE PROCESSING >COLOR SPACES UTRECHT UNIVERSITY RONALD POPPE

IMAGE PROCESSING >COLOR SPACES UTRECHT UNIVERSITY RONALD POPPE IMAGE PROCESSING >COLOR SPACES UTRECHT UNIVERSITY RONALD POPPE OUTLINE Human visual system Color images Color quantization Colorimetric color spaces HUMAN VISUAL SYSTEM HUMAN VISUAL SYSTEM HUMAN VISUAL

More information

Geography 360 Principles of Cartography. April 24, 2006

Geography 360 Principles of Cartography. April 24, 2006 Geography 360 Principles of Cartography April 24, 2006 Outlines 1. Principles of color Color as physical phenomenon Color as physiological phenomenon 2. How is color specified? (color model) Hardware-oriented

More information

Hello, welcome to the video lecture series on Digital image processing. (Refer Slide Time: 00:30)

Hello, welcome to the video lecture series on Digital image processing. (Refer Slide Time: 00:30) Digital Image Processing Prof. P. K. Biswas Department of Electronics and Electrical Communications Engineering Indian Institute of Technology, Kharagpur Module 11 Lecture Number 52 Conversion of one Color

More information

Introduction to Color Science (Cont)

Introduction to Color Science (Cont) Lecture 24: Introduction to Color Science (Cont) Computer Graphics and Imaging UC Berkeley Empirical Color Matching Experiment Additive Color Matching Experiment Show test light spectrum on left Mix primaries

More information

VC 16/17 TP4 Colour and Noise

VC 16/17 TP4 Colour and Noise VC 16/17 TP4 Colour and Noise Mestrado em Ciência de Computadores Mestrado Integrado em Engenharia de Redes e Sistemas Informáticos Hélder Filipe Pinto de Oliveira Outline Colour spaces Colour processing

More information

Color. Chapter 6. (colour) Digital Multimedia, 2nd edition

Color. Chapter 6. (colour) Digital Multimedia, 2nd edition Color (colour) Chapter 6 Digital Multimedia, 2nd edition What is color? Color is how our eyes perceive different forms of energy. Energy moves in the form of waves. What is a wave? Think of a fat guy (Dr.

More information

Victor Ostromoukhov Université de Montréal. Victor Ostromoukhov - Université de Montréal

Victor Ostromoukhov Université de Montréal. Victor Ostromoukhov - Université de Montréal IFT3355 Victor Ostromoukhov Université de Montréal full world 2 1 in art history Mondrian 1921 The cave of Lascaux About 17000 BC Vermeer mid-xvii century 3 is one of the most effective visual attributes

More information

any kind, you have two receptive fields, one the small center region, the other the surround region.

any kind, you have two receptive fields, one the small center region, the other the surround region. In a centersurround cell of any kind, you have two receptive fields, one the small center region, the other the surround region. + _ In a chromatic center-surround field, each in innervated by one class

More information

Light and Colour. Light as part of the EM spectrum. Light as part of the EM spectrum

Light and Colour. Light as part of the EM spectrum. Light as part of the EM spectrum Light and Colour Prof. Grega Bizjak, PhD Laboratory of Lighting and Photometry Faculty of Electrical Engineering University of Ljubljana Light as part of the EM spectrum Visible light can be seen as part

More information

Color. Bilkent University. CS554 Computer Vision Pinar Duygulu

Color. Bilkent University. CS554 Computer Vision Pinar Duygulu 1 Color CS 554 Computer Vision Pinar Duygulu Bilkent University 2 What is light? Electromagnetic radiation (EMR) moving along rays in space R(λ) is EMR, measured in units of power (watts) λ is wavelength

More information

Vision and color. University of Texas at Austin CS384G - Computer Graphics Fall 2010 Don Fussell

Vision and color. University of Texas at Austin CS384G - Computer Graphics Fall 2010 Don Fussell Vision and color University of Texas at Austin CS384G - Computer Graphics Fall 2010 Don Fussell Reading Glassner, Principles of Digital Image Synthesis, pp. 5-32. Watt, Chapter 15. Brian Wandell. Foundations

More information

Color. Color. Colorfull world IFT3350. Victor Ostromoukhov Université de Montréal. Victor Ostromoukhov - Université de Montréal

Color. Color. Colorfull world IFT3350. Victor Ostromoukhov Université de Montréal. Victor Ostromoukhov - Université de Montréal IFT3350 Victor Ostromoukhov Université de Montréal full world 2 1 in art history Mondrian 1921 The cave of Lascaux About 17000 BC Vermeer mid-xvii century 3 is one of the most effective visual attributes

More information

Digital Image Processing Chapter 6: Color Image Processing ( )

Digital Image Processing Chapter 6: Color Image Processing ( ) Digital Image Processing Chapter 6: Color Image Processing (6.1 6.3) 6. Preview The process followed by the human brain in perceiving and interpreting color is a physiopsychological henomenon that is not

More information

Color image processing

Color image processing Color image processing Color images C1 C2 C3 Each colored pixel corresponds to a vector of three values {C1,C2,C3} The characteristics of the components depend on the chosen colorspace (RGB, YUV, CIELab,..)

More information

MATH 5300 Lecture 3- Summary Date: May 12, 2008 By: Violeta Constantin

MATH 5300 Lecture 3- Summary Date: May 12, 2008 By: Violeta Constantin MATH 5300 Lecture 3- Summary Date: May 12, 2008 By: Violeta Constantin Facebook, Blogs and Wiki tools for sharing ideas or presenting work Using Facebook as a tool to ask questions - discussion on GIMP

More information

Reading instructions: Chapter 6

Reading instructions: Chapter 6 Lecture 8 in Computerized Image Analysis Digital Color Processing Hamid Sarve hamid@cb.uu.se Reading instructions: Chapter 6 Electromagnetic Radiation Visible light (for humans) is electromagnetic radiation

More information

Additive. Subtractive

Additive. Subtractive Physics 106 Additive Subtractive Subtractive Mixing Rules: Mixing Cyan + Magenta, one gets Blue Mixing Cyan + Yellow, one gets Green Mixing Magenta + Yellow, one gets Red Mixing any two of the Blue, Red,

More information

Interactive Computer Graphics

Interactive Computer Graphics Interactive Computer Graphics Lecture 4: Colour Graphics Lecture 4: Slide 1 Ways of looking at colour 1. Physics 2. Human visual receptors 3. Subjective assessment Graphics Lecture 4: Slide 2 The physics

More information

Color, Vision, & Perception. Outline

Color, Vision, & Perception. Outline Color, Vision, & Perception CS 160, Fall 97 Professor James Landay September 24, 1997 9/24/97 1 Outline Administrivia Review Human visual system Color perception Color deficiency Guidelines for design

More information

Digital Image Processing. Lecture # 6 Corner Detection & Color Processing

Digital Image Processing. Lecture # 6 Corner Detection & Color Processing Digital Image Processing Lecture # 6 Corner Detection & Color Processing 1 Corners Corners (interest points) Unlike edges, corners (patches of pixels surrounding the corner) do not necessarily correspond

More information

Using Color in Scientific Visualization

Using Color in Scientific Visualization Using Color in Scientific Visualization Mike Bailey The often scant benefits derived from coloring data indicate that even putting a good color in a good place is a complex matter. Indeed, so difficult

More information

COLOR AS A DESIGN ELEMENT

COLOR AS A DESIGN ELEMENT COLOR COLOR AS A DESIGN ELEMENT Color is one of the most important elements of design. It can evoke action and emotion. It can attract or detract attention. I. COLOR SETS COLOR HARMONY Color Harmony occurs

More information

Visual Imaging and the Electronic Age Color Science

Visual Imaging and the Electronic Age Color Science Visual Imaging and the Electronic Age Color Science Grassman s Experiments & Trichromacy Lecture #5 September 5, 2017 Prof. Donald P. Greenberg Light as Rays Light as Waves Light as Photons What is Color

More information

Color + Quality. 1. Description of Color

Color + Quality. 1. Description of Color Color + Quality 1. Description of Color Agenda Part 1: Description of color - Sensation of color -Light sources -Standard light -Additive und subtractive colormixing -Complementary colors -Reflection and

More information

Introduction to Color

Introduction to Color Introduction to Color Andries van Dam September 30, 2003 Introduction to Computer Graphics 1/82 All You Need to Know About Color in CS123 Andries van Dam September 30, 2003 Introduction to Computer Graphics

More information

Chapter 2 Fundamentals of Digital Imaging

Chapter 2 Fundamentals of Digital Imaging Chapter 2 Fundamentals of Digital Imaging Part 4 Color Representation 1 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

More information

Color images C1 C2 C3

Color images C1 C2 C3 Color imaging Color images C1 C2 C3 Each colored pixel corresponds to a vector of three values {C1,C2,C3} The characteristics of the components depend on the chosen colorspace (RGB, YUV, CIELab,..) Digital

More information