SlideShare uma empresa Scribd logo
1 de 17
Baixar para ler offline
Color


                                         1




               Color

To understand how to make realistic
images, we need a basic understanding of
the physics and physiology of vision. Here
we step away from the code and math for
a bit to talk about basic principles.




                                             2




                                                 1
Basics Of Color
• elements of color:




                                                      3




         Basics of Color
   • Physics:
     – Illumination
        • Electromagnetic spectra
     – Reflection
        • Material properties
        • Surface geometry and microgeometry (i.e.,
          polished versus matte versus brushed)
   • Perception
     – Physiology and neurophysiology
     – Perceptual psychology
                                                      4




                                                          2
Electromagnetic Spectrum




                           5




    Theory of color




                           6




                               3
Theory of color (Goethe)




                            7




Theory of color (Goethe)




                            8




                                4
White Light
• Sun or light bulbs emit all frequencies
  within the visible range to produce
  what we perceive as the quot;white lightquot;




                                            9




       Sunlight Spectrum




                                        10




                                                5
White Light and Color

• when white light is incident upon an
  object, some frequencies are
  reflected and some are absorbed by
  the object
• combination of frequencies present
  in the reflected light that
  determines what we perceive as the
  color of the object

                                         11




           Reflection




                                         12




                                              6
Physiology of Vision

• The eye:
• The retina
  – Rods
  – Cones
    • Color!




                                13




               Photoreceptors




                                14




                                     7
15




     Physiology of Vision
• The center of the retina is a densely
  packed region called the fovea.
  – Cones much denser here than the
   periphery




                                          16




                                               8
Trichromacy
• three types of cones
  – L or R, most sensitive to red light (610 nm)
  – M or G, most sensitive to green light (560 nm)
  – S or B, most sensitive to blue light (430 nm)




  – color blindness results from missing cone type(s)
                                                              17




   Trichromats
  (with a special
                                • Some animals – for example
   sensitivity to                 bees – have three types of
                                  cones. Two of the cones are
    ultraviolet)                  sensitive to quot;human visiblequot;
                                  wavelengths. The third cone
                                  is sensitive to colors in the
                                  ultraviolet range of the
                                  spectrum.
                                  This cone enables them to
                                  see colors that humans can’t
                                  see.

                                   They also perceive human-
                                   visible spectra in different
                                   hues than those that humans
                                   experience

       http://www.colormatters.com/kids/eye.html
                                                              18




                                                                   9
• Most bird species (that
                               have been studied) have
Tetrachromats                  at least four types of
                               cones. They are
                               quot;tetrachromats.quot;
                               Recent studies have
                               confirmed
                               tetrachromacy in some
                               fish and turtles.

                                Perhaps it is mammals,
                                including humans, that
                                have poor color vision!



  http://www.bio.bris.ac.uk/research/vision/4d.htm
                                                            19




                             • It has been suggested that
                               some women are also
Tetrachromats                  tetrachromats. One study
                               suggested that 2-3% of the
                               world's women may have the
                               kind of fourth cone that
                               gives a significant increase
                               in color differentiation.
                             •
                               Another thing to consider:
                               Some data suggests that the
                               architecture of the human
                               visual system (as well as that
                               of many animals) is really
                               tetrachromatic - but that
                               this capacity is blocked.


  http://en.wikipedia.org/wiki/Tetrachromat
  http://www.4colorvision.com/files/tetrachromat.htm       20




                                                                 10
• Many animals have only
    Dichromats                                                       two kinds of cones in
                                                                     their eyes. They are
                                                                     known as “dichromats.”
                                                                     It’s worth noting that
                                                                     the color-sensing
                                                                     pigment in these cones
                                                                     may be weak.
                                                                     Therefore, an animal –
                                                                     for example a dog -
                                                                     probably sees very weak
                                                                     colors.


         http://en.wikipedia.org/wiki/Tetrachromat
         http://www.4colorvision.com/files/tetrachromat.htm                                                                               21




                               Receptors in Retina
•    Receptors contain photopigments that produce electro-chemical
     response; our dynamic range of light, from a few photons to looking at
     the sun,        is 1011 => division of labor among receptors
•    Rods (scotopic): only see grays, work in low-light/night conditions,
     mostly in periphery
•    Cones (photopic): respond to different wavelength to produce color
     sensations, work in bright light, densely packed near fovea, center of
     retina, fewer in periphery
•    Young-Helmholtz tristimulus theory1: 3 types of cones, each sensitive
     to all visible wavelengths of light, each maximally responsive in
     different ranges, often associated with red, green, and blue (although
     red and green peaks of these cones actually more yellow)
•    The three types of receptors can produce a 3-space of hue, saturation
     and value (lightness/brightness)
•    To avoid misinterpretations S (short), I (intermediate), L (long) often
     used instead


    1Thomas Young proposed the idea of three receptors in 1801. Hermann von Helmholtz looked at the theory from a quantitative basis

    in 1866. Hence, although they did not work together, the theory is called the Young-Helmholtz theory since they arrived at the same
    conclusions.
                                                                                                                                          22




                                                                                                                                               11
Humans and Light
• when we view a source of light, our
  eyes respond to
  – hue: the color we see (red, green, purple)
    • dominant frequency
  – saturation: how far is color from grey
    • how far is the color from gray (pink is less
      saturated than red, sky blue is less saturated
      than royal blue)
  – brightness: how bright is the color
    • how bright are the lights illuminating the
      object?
                                                   23




                    Hue
 • hue (or simply, quot;colorquot;) is dominant
   wavelength




   – integration of energy for all visible
     wavelengths is proportional to intensity of
     color
                                                   24




                                                        12
Saturation or Purity of Light
• how washed out or how pure the color of
  the light appears
  – contribution of dominant light vs. other
    frequencies producing white light




                                               25




     Intensity, Brightness
 • intensity : radiant energy emitted
   per unit of time, per unit solid angle,
   and per unit projected area of the
   source (related to the luminance of
   the source)

 • brightness : perceived intensity of
   light. One may lower the intensity by
   adding white or black.

                                               26




                                                    13
Perception of Color
• Human eyes can not differentiate
  between spectral yellow and any
  combination of red and green




                                      27




               Activity




                                     28




                                           14
Do all of the red squares look the
 same or do they look different?




                                     29




                                     30




                                          15
31




               Metamers

  a given perceptual sensation of color
  derives from the stimulus of all three
  cone types




• identical perceptions of color can thus be
  caused by very different spectra             32




                                                    16
Metamer Demo
•   http://www.cs.brown.edu/exploratories/freeSoftware/catalogs/color_theory.h
    tml




                                                                            33




                                                                                 17

Mais conteúdo relacionado

Semelhante a Color

The Membrane Of The Cone Cells
The Membrane Of The Cone CellsThe Membrane Of The Cone Cells
The Membrane Of The Cone CellsMindi Schneider
 
When The Senses Fail You Essay
When The Senses Fail You EssayWhen The Senses Fail You Essay
When The Senses Fail You EssayAlicia Johnson
 
Color Blindness And Testing In Children Essay
Color Blindness And Testing In Children EssayColor Blindness And Testing In Children Essay
Color Blindness And Testing In Children EssayDeborah Quintana
 
Human color vision
Human color visionHuman color vision
Human color visionAbu Sayed
 
IB Sl Physics Sight and Waves Flippingphysics by Nothingnerdy
IB Sl Physics Sight and Waves Flippingphysics by NothingnerdyIB Sl Physics Sight and Waves Flippingphysics by Nothingnerdy
IB Sl Physics Sight and Waves Flippingphysics by NothingnerdyNothingnerdy
 
独中高中生物Chapter 12 Receptors and sensation
独中高中生物Chapter 12 Receptors and sensation独中高中生物Chapter 12 Receptors and sensation
独中高中生物Chapter 12 Receptors and sensationYee Sing Ong
 
Insectvision 161127070950
Insectvision 161127070950Insectvision 161127070950
Insectvision 161127070950DiyaMalik4
 
Introductory Psychology: Sensation & Perception (Vision)
Introductory Psychology: Sensation & Perception (Vision)Introductory Psychology: Sensation & Perception (Vision)
Introductory Psychology: Sensation & Perception (Vision)Brian Piper
 
Cinder Cone Research Paper
Cinder Cone Research PaperCinder Cone Research Paper
Cinder Cone Research PaperAnna Melek
 
Animal vision nsta 102911
Animal vision nsta 102911Animal vision nsta 102911
Animal vision nsta 102911guisbond
 
Research Paper On Colorblinness
Research Paper On ColorblinnessResearch Paper On Colorblinness
Research Paper On ColorblinnessMia Malone
 
Cone-Beams Tomography Report
Cone-Beams Tomography ReportCone-Beams Tomography Report
Cone-Beams Tomography ReportAmber Butler
 
insect vision, entomology, insect eye facet
insect vision, entomology, insect eye facetinsect vision, entomology, insect eye facet
insect vision, entomology, insect eye facetagri20
 

Semelhante a Color (20)

The Membrane Of The Cone Cells
The Membrane Of The Cone CellsThe Membrane Of The Cone Cells
The Membrane Of The Cone Cells
 
Cones Lab Report
Cones Lab ReportCones Lab Report
Cones Lab Report
 
Visual Acuity
Visual AcuityVisual Acuity
Visual Acuity
 
Eye Facts
Eye FactsEye Facts
Eye Facts
 
When The Senses Fail You Essay
When The Senses Fail You EssayWhen The Senses Fail You Essay
When The Senses Fail You Essay
 
Color Blindness And Testing In Children Essay
Color Blindness And Testing In Children EssayColor Blindness And Testing In Children Essay
Color Blindness And Testing In Children Essay
 
Human color vision
Human color visionHuman color vision
Human color vision
 
IB Sl Physics Sight and Waves Flippingphysics by Nothingnerdy
IB Sl Physics Sight and Waves Flippingphysics by NothingnerdyIB Sl Physics Sight and Waves Flippingphysics by Nothingnerdy
IB Sl Physics Sight and Waves Flippingphysics by Nothingnerdy
 
独中高中生物Chapter 12 Receptors and sensation
独中高中生物Chapter 12 Receptors and sensation独中高中生物Chapter 12 Receptors and sensation
独中高中生物Chapter 12 Receptors and sensation
 
Insectvision 161127070950
Insectvision 161127070950Insectvision 161127070950
Insectvision 161127070950
 
Insect vision
Insect visionInsect vision
Insect vision
 
Introductory Psychology: Sensation & Perception (Vision)
Introductory Psychology: Sensation & Perception (Vision)Introductory Psychology: Sensation & Perception (Vision)
Introductory Psychology: Sensation & Perception (Vision)
 
2012 Ch4 Vision
2012 Ch4 Vision2012 Ch4 Vision
2012 Ch4 Vision
 
Cinder Cone Research Paper
Cinder Cone Research PaperCinder Cone Research Paper
Cinder Cone Research Paper
 
Animal vision nsta 102911
Animal vision nsta 102911Animal vision nsta 102911
Animal vision nsta 102911
 
Research Paper On Colorblinness
Research Paper On ColorblinnessResearch Paper On Colorblinness
Research Paper On Colorblinness
 
Perception
PerceptionPerception
Perception
 
Cone-Beams Tomography Report
Cone-Beams Tomography ReportCone-Beams Tomography Report
Cone-Beams Tomography Report
 
insect vision, entomology, insect eye facet
insect vision, entomology, insect eye facetinsect vision, entomology, insect eye facet
insect vision, entomology, insect eye facet
 
Color theory part 2
Color theory part 2Color theory part 2
Color theory part 2
 

Mais de johanna20

Digitales examen 1
Digitales examen 1Digitales examen 1
Digitales examen 1johanna20
 
Digitales examen 2
Digitales examen 2Digitales examen 2
Digitales examen 2johanna20
 
Digitales examen 1
Digitales examen 1Digitales examen 1
Digitales examen 1johanna20
 
Datos Escalares
Datos EscalaresDatos Escalares
Datos Escalaresjohanna20
 
examen fisica c
examen fisica cexamen fisica c
examen fisica cjohanna20
 
Examen Fisica
Examen FisicaExamen Fisica
Examen Fisicajohanna20
 
EXamen Fisica Parcial Termino2004
EXamen Fisica Parcial Termino2004EXamen Fisica Parcial Termino2004
EXamen Fisica Parcial Termino2004johanna20
 
Gramaticas Regulares
Gramaticas RegularesGramaticas Regulares
Gramaticas Regularesjohanna20
 
Ciclo Contable De Una Empresa Comercial
Ciclo Contable De Una Empresa  ComercialCiclo Contable De Una Empresa  Comercial
Ciclo Contable De Una Empresa Comercialjohanna20
 
Ajustes y Actualizaciones
Ajustes y ActualizacionesAjustes y Actualizaciones
Ajustes y Actualizacionesjohanna20
 
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)johanna20
 
Ciclo Contable De Una Empresa Comercial Parte I
Ciclo Contable De Una Empresa  Comercial Parte ICiclo Contable De Una Empresa  Comercial Parte I
Ciclo Contable De Una Empresa Comercial Parte Ijohanna20
 
Ciclo Contable
Ciclo ContableCiclo Contable
Ciclo Contablejohanna20
 
Conceptos Basicos
Conceptos BasicosConceptos Basicos
Conceptos Basicosjohanna20
 
Introduccion A Sistemas De Informacion
Introduccion A Sistemas De InformacionIntroduccion A Sistemas De Informacion
Introduccion A Sistemas De Informacionjohanna20
 

Mais de johanna20 (20)

Digitales examen 1
Digitales examen 1Digitales examen 1
Digitales examen 1
 
Digitales examen 2
Digitales examen 2Digitales examen 2
Digitales examen 2
 
Digitales examen 1
Digitales examen 1Digitales examen 1
Digitales examen 1
 
Adt
AdtAdt
Adt
 
Arreglos
ArreglosArreglos
Arreglos
 
Datos Escalares
Datos EscalaresDatos Escalares
Datos Escalares
 
examen fisica c
examen fisica cexamen fisica c
examen fisica c
 
Examen Fisica
Examen FisicaExamen Fisica
Examen Fisica
 
EXamen Fisica Parcial Termino2004
EXamen Fisica Parcial Termino2004EXamen Fisica Parcial Termino2004
EXamen Fisica Parcial Termino2004
 
Gramaticas Regulares
Gramaticas RegularesGramaticas Regulares
Gramaticas Regulares
 
Ciclo Contable De Una Empresa Comercial
Ciclo Contable De Una Empresa  ComercialCiclo Contable De Una Empresa  Comercial
Ciclo Contable De Una Empresa Comercial
 
Ajustes y Actualizaciones
Ajustes y ActualizacionesAjustes y Actualizaciones
Ajustes y Actualizaciones
 
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)
Ciclo Contable De Una Empresa Comercial Parte Ii.Ppt(3parte)
 
Ciclo Contable De Una Empresa Comercial Parte I
Ciclo Contable De Una Empresa  Comercial Parte ICiclo Contable De Una Empresa  Comercial Parte I
Ciclo Contable De Una Empresa Comercial Parte I
 
Ciclo Contable
Ciclo ContableCiclo Contable
Ciclo Contable
 
Conceptos Basicos
Conceptos BasicosConceptos Basicos
Conceptos Basicos
 
Introduccion A Sistemas De Informacion
Introduccion A Sistemas De InformacionIntroduccion A Sistemas De Informacion
Introduccion A Sistemas De Informacion
 
Clipping
ClippingClipping
Clipping
 
Iluminacion
IluminacionIluminacion
Iluminacion
 
Hilos
HilosHilos
Hilos
 

Último

Patch notes explaining DISARM Version 1.4 update
Patch notes explaining DISARM Version 1.4 updatePatch notes explaining DISARM Version 1.4 update
Patch notes explaining DISARM Version 1.4 updateadam112203
 
Where developers are challenged, what developers want and where DevEx is going
Where developers are challenged, what developers want and where DevEx is goingWhere developers are challenged, what developers want and where DevEx is going
Where developers are challenged, what developers want and where DevEx is goingFrancesco Corti
 
How to release an Open Source Dataweave Library
How to release an Open Source Dataweave LibraryHow to release an Open Source Dataweave Library
How to release an Open Source Dataweave Libraryshyamraj55
 
Extra-120324-Visite-Entreprise-icare.pdf
Extra-120324-Visite-Entreprise-icare.pdfExtra-120324-Visite-Entreprise-icare.pdf
Extra-120324-Visite-Entreprise-icare.pdfInfopole1
 
Stobox 4: Revolutionizing Investment in Real-World Assets Through Tokenization
Stobox 4: Revolutionizing Investment in Real-World Assets Through TokenizationStobox 4: Revolutionizing Investment in Real-World Assets Through Tokenization
Stobox 4: Revolutionizing Investment in Real-World Assets Through TokenizationStobox
 
TrustArc Webinar - How to Live in a Post Third-Party Cookie World
TrustArc Webinar - How to Live in a Post Third-Party Cookie WorldTrustArc Webinar - How to Live in a Post Third-Party Cookie World
TrustArc Webinar - How to Live in a Post Third-Party Cookie WorldTrustArc
 
IT Service Management (ITSM) Best Practices for Advanced Computing
IT Service Management (ITSM) Best Practices for Advanced ComputingIT Service Management (ITSM) Best Practices for Advanced Computing
IT Service Management (ITSM) Best Practices for Advanced ComputingMAGNIntelligence
 
Flow Control | Block Size | ST Min | First Frame
Flow Control | Block Size | ST Min | First FrameFlow Control | Block Size | ST Min | First Frame
Flow Control | Block Size | ST Min | First FrameKapil Thakar
 
LF Energy Webinar - Unveiling OpenEEMeter 4.0
LF Energy Webinar - Unveiling OpenEEMeter 4.0LF Energy Webinar - Unveiling OpenEEMeter 4.0
LF Energy Webinar - Unveiling OpenEEMeter 4.0DanBrown980551
 
UiPath Studio Web workshop Series - Day 3
UiPath Studio Web workshop Series - Day 3UiPath Studio Web workshop Series - Day 3
UiPath Studio Web workshop Series - Day 3DianaGray10
 
UiPath Studio Web workshop series - Day 4
UiPath Studio Web workshop series - Day 4UiPath Studio Web workshop series - Day 4
UiPath Studio Web workshop series - Day 4DianaGray10
 
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptx
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptxGraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptx
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptxNeo4j
 
Planetek Italia Srl - Corporate Profile Brochure
Planetek Italia Srl - Corporate Profile BrochurePlanetek Italia Srl - Corporate Profile Brochure
Planetek Italia Srl - Corporate Profile BrochurePlanetek Italia Srl
 
Explore the UiPath Community and ways you can benefit on your journey to auto...
Explore the UiPath Community and ways you can benefit on your journey to auto...Explore the UiPath Community and ways you can benefit on your journey to auto...
Explore the UiPath Community and ways you can benefit on your journey to auto...DianaGray10
 
UiPath Studio Web workshop series - Day 2
UiPath Studio Web workshop series - Day 2UiPath Studio Web workshop series - Day 2
UiPath Studio Web workshop series - Day 2DianaGray10
 
EMEA What is ThousandEyes? Webinar
EMEA What is ThousandEyes? WebinarEMEA What is ThousandEyes? Webinar
EMEA What is ThousandEyes? WebinarThousandEyes
 
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - Tech
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - TechWebinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - Tech
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - TechProduct School
 
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024Alkin Tezuysal
 
.NET 8 ChatBot with Azure OpenAI Services.pptx
.NET 8 ChatBot with Azure OpenAI Services.pptx.NET 8 ChatBot with Azure OpenAI Services.pptx
.NET 8 ChatBot with Azure OpenAI Services.pptxHansamali Gamage
 
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptx
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptxEmil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptx
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptxNeo4j
 

Último (20)

Patch notes explaining DISARM Version 1.4 update
Patch notes explaining DISARM Version 1.4 updatePatch notes explaining DISARM Version 1.4 update
Patch notes explaining DISARM Version 1.4 update
 
Where developers are challenged, what developers want and where DevEx is going
Where developers are challenged, what developers want and where DevEx is goingWhere developers are challenged, what developers want and where DevEx is going
Where developers are challenged, what developers want and where DevEx is going
 
How to release an Open Source Dataweave Library
How to release an Open Source Dataweave LibraryHow to release an Open Source Dataweave Library
How to release an Open Source Dataweave Library
 
Extra-120324-Visite-Entreprise-icare.pdf
Extra-120324-Visite-Entreprise-icare.pdfExtra-120324-Visite-Entreprise-icare.pdf
Extra-120324-Visite-Entreprise-icare.pdf
 
Stobox 4: Revolutionizing Investment in Real-World Assets Through Tokenization
Stobox 4: Revolutionizing Investment in Real-World Assets Through TokenizationStobox 4: Revolutionizing Investment in Real-World Assets Through Tokenization
Stobox 4: Revolutionizing Investment in Real-World Assets Through Tokenization
 
TrustArc Webinar - How to Live in a Post Third-Party Cookie World
TrustArc Webinar - How to Live in a Post Third-Party Cookie WorldTrustArc Webinar - How to Live in a Post Third-Party Cookie World
TrustArc Webinar - How to Live in a Post Third-Party Cookie World
 
IT Service Management (ITSM) Best Practices for Advanced Computing
IT Service Management (ITSM) Best Practices for Advanced ComputingIT Service Management (ITSM) Best Practices for Advanced Computing
IT Service Management (ITSM) Best Practices for Advanced Computing
 
Flow Control | Block Size | ST Min | First Frame
Flow Control | Block Size | ST Min | First FrameFlow Control | Block Size | ST Min | First Frame
Flow Control | Block Size | ST Min | First Frame
 
LF Energy Webinar - Unveiling OpenEEMeter 4.0
LF Energy Webinar - Unveiling OpenEEMeter 4.0LF Energy Webinar - Unveiling OpenEEMeter 4.0
LF Energy Webinar - Unveiling OpenEEMeter 4.0
 
UiPath Studio Web workshop Series - Day 3
UiPath Studio Web workshop Series - Day 3UiPath Studio Web workshop Series - Day 3
UiPath Studio Web workshop Series - Day 3
 
UiPath Studio Web workshop series - Day 4
UiPath Studio Web workshop series - Day 4UiPath Studio Web workshop series - Day 4
UiPath Studio Web workshop series - Day 4
 
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptx
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptxGraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptx
GraphSummit Copenhagen 2024 - Neo4j Vision and Roadmap.pptx
 
Planetek Italia Srl - Corporate Profile Brochure
Planetek Italia Srl - Corporate Profile BrochurePlanetek Italia Srl - Corporate Profile Brochure
Planetek Italia Srl - Corporate Profile Brochure
 
Explore the UiPath Community and ways you can benefit on your journey to auto...
Explore the UiPath Community and ways you can benefit on your journey to auto...Explore the UiPath Community and ways you can benefit on your journey to auto...
Explore the UiPath Community and ways you can benefit on your journey to auto...
 
UiPath Studio Web workshop series - Day 2
UiPath Studio Web workshop series - Day 2UiPath Studio Web workshop series - Day 2
UiPath Studio Web workshop series - Day 2
 
EMEA What is ThousandEyes? Webinar
EMEA What is ThousandEyes? WebinarEMEA What is ThousandEyes? Webinar
EMEA What is ThousandEyes? Webinar
 
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - Tech
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - TechWebinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - Tech
Webinar: The Art of Prioritizing Your Product Roadmap by AWS Sr PM - Tech
 
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024
Design and Modeling for MySQL SCALE 21X Pasadena, CA Mar 2024
 
.NET 8 ChatBot with Azure OpenAI Services.pptx
.NET 8 ChatBot with Azure OpenAI Services.pptx.NET 8 ChatBot with Azure OpenAI Services.pptx
.NET 8 ChatBot with Azure OpenAI Services.pptx
 
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptx
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptxEmil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptx
Emil Eifrem at GraphSummit Copenhagen 2024 - The Art of the Possible.pptx
 

Color

  • 1. Color 1 Color To understand how to make realistic images, we need a basic understanding of the physics and physiology of vision. Here we step away from the code and math for a bit to talk about basic principles. 2 1
  • 2. Basics Of Color • elements of color: 3 Basics of Color • Physics: – Illumination • Electromagnetic spectra – Reflection • Material properties • Surface geometry and microgeometry (i.e., polished versus matte versus brushed) • Perception – Physiology and neurophysiology – Perceptual psychology 4 2
  • 3. Electromagnetic Spectrum 5 Theory of color 6 3
  • 4. Theory of color (Goethe) 7 Theory of color (Goethe) 8 4
  • 5. White Light • Sun or light bulbs emit all frequencies within the visible range to produce what we perceive as the quot;white lightquot; 9 Sunlight Spectrum 10 5
  • 6. White Light and Color • when white light is incident upon an object, some frequencies are reflected and some are absorbed by the object • combination of frequencies present in the reflected light that determines what we perceive as the color of the object 11 Reflection 12 6
  • 7. Physiology of Vision • The eye: • The retina – Rods – Cones • Color! 13 Photoreceptors 14 7
  • 8. 15 Physiology of Vision • The center of the retina is a densely packed region called the fovea. – Cones much denser here than the periphery 16 8
  • 9. Trichromacy • three types of cones – L or R, most sensitive to red light (610 nm) – M or G, most sensitive to green light (560 nm) – S or B, most sensitive to blue light (430 nm) – color blindness results from missing cone type(s) 17 Trichromats (with a special • Some animals – for example sensitivity to bees – have three types of cones. Two of the cones are ultraviolet) sensitive to quot;human visiblequot; wavelengths. The third cone is sensitive to colors in the ultraviolet range of the spectrum. This cone enables them to see colors that humans can’t see. They also perceive human- visible spectra in different hues than those that humans experience http://www.colormatters.com/kids/eye.html 18 9
  • 10. • Most bird species (that have been studied) have Tetrachromats at least four types of cones. They are quot;tetrachromats.quot; Recent studies have confirmed tetrachromacy in some fish and turtles. Perhaps it is mammals, including humans, that have poor color vision! http://www.bio.bris.ac.uk/research/vision/4d.htm 19 • It has been suggested that some women are also Tetrachromats tetrachromats. One study suggested that 2-3% of the world's women may have the kind of fourth cone that gives a significant increase in color differentiation. • Another thing to consider: Some data suggests that the architecture of the human visual system (as well as that of many animals) is really tetrachromatic - but that this capacity is blocked. http://en.wikipedia.org/wiki/Tetrachromat http://www.4colorvision.com/files/tetrachromat.htm 20 10
  • 11. • Many animals have only Dichromats two kinds of cones in their eyes. They are known as “dichromats.” It’s worth noting that the color-sensing pigment in these cones may be weak. Therefore, an animal – for example a dog - probably sees very weak colors. http://en.wikipedia.org/wiki/Tetrachromat http://www.4colorvision.com/files/tetrachromat.htm 21 Receptors in Retina • Receptors contain photopigments that produce electro-chemical response; our dynamic range of light, from a few photons to looking at the sun, is 1011 => division of labor among receptors • Rods (scotopic): only see grays, work in low-light/night conditions, mostly in periphery • Cones (photopic): respond to different wavelength to produce color sensations, work in bright light, densely packed near fovea, center of retina, fewer in periphery • Young-Helmholtz tristimulus theory1: 3 types of cones, each sensitive to all visible wavelengths of light, each maximally responsive in different ranges, often associated with red, green, and blue (although red and green peaks of these cones actually more yellow) • The three types of receptors can produce a 3-space of hue, saturation and value (lightness/brightness) • To avoid misinterpretations S (short), I (intermediate), L (long) often used instead 1Thomas Young proposed the idea of three receptors in 1801. Hermann von Helmholtz looked at the theory from a quantitative basis in 1866. Hence, although they did not work together, the theory is called the Young-Helmholtz theory since they arrived at the same conclusions. 22 11
  • 12. Humans and Light • when we view a source of light, our eyes respond to – hue: the color we see (red, green, purple) • dominant frequency – saturation: how far is color from grey • how far is the color from gray (pink is less saturated than red, sky blue is less saturated than royal blue) – brightness: how bright is the color • how bright are the lights illuminating the object? 23 Hue • hue (or simply, quot;colorquot;) is dominant wavelength – integration of energy for all visible wavelengths is proportional to intensity of color 24 12
  • 13. Saturation or Purity of Light • how washed out or how pure the color of the light appears – contribution of dominant light vs. other frequencies producing white light 25 Intensity, Brightness • intensity : radiant energy emitted per unit of time, per unit solid angle, and per unit projected area of the source (related to the luminance of the source) • brightness : perceived intensity of light. One may lower the intensity by adding white or black. 26 13
  • 14. Perception of Color • Human eyes can not differentiate between spectral yellow and any combination of red and green 27 Activity 28 14
  • 15. Do all of the red squares look the same or do they look different? 29 30 15
  • 16. 31 Metamers a given perceptual sensation of color derives from the stimulus of all three cone types • identical perceptions of color can thus be caused by very different spectra 32 16
  • 17. Metamer Demo • http://www.cs.brown.edu/exploratories/freeSoftware/catalogs/color_theory.h tml 33 17