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Why we don’t know
              how many colors there are
            Ján Morovič, Vien Cheung* & Peter Morovič
          ...
How many colors are there?




   28 × 28 × 28 = ~ 16.8 million




    3                              infinity
How many colors are there?



    o  interesting!

    o  usefulness in engineering decision processes

    o  but ... wha...
What does ‘all possible colors’
mean?




                16 million | 2-10 million

              CIE system | visual sys...
Color illusions


     o  the notion of color is essentially a property of an
     object does not explain color illusions
Color ‘illusions’




                [255 0 0]



       physical colors > perceptual colors
       physical colors < col...
Related studies
     2010   Maric-France & Foster


     2008   Linhares et al.


     2005   Heckaman et al.
            ...
Our work



    o  counting all possible colors ‘by hand’


    o  computationally predicting all possible colors


    o ...
Counting colors ‘by hand’




   o  this exercise can tell us how many colors there are on a gray
   background, when view...
Counting colors ‘by hand’
Computational prediction



    o  an ecosystem enabling varying color experiences

    o  CIECAM02

    o  color appearan...
Computational prediction
Computational prediction

 Light source                   D50                     F11



   Surround       average       d...
Computational prediction

   o  expanding to standard iluminants to freely varying their SPD

   o  242 synthetic light so...
Computational prediction


  o  CIECAM02 dramatically predicts color gamut with 1011 volumes
  in Jab space


  o  i.e. 10...
Computational prediction

  o  a revised prediction uses 173 measured light sources
                                      ...
Computational prediction


         0.5


                                                                               1...
Computational prediction
                                          200                                                    ...
CAM


 o  Note that CIECAM02 does not include
 many complexities of colour vision
 such as contrast effects


 o  using CA...
Conclusions



 o  based upon the available data to-date there are at
 least ~1.7 million colors


 o  to go beyond this t...
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Why we don’t know how many colors there are Slide 1 Why we don’t know how many colors there are Slide 2 Why we don’t know how many colors there are Slide 3 Why we don’t know how many colors there are Slide 4 Why we don’t know how many colors there are Slide 5 Why we don’t know how many colors there are Slide 6 Why we don’t know how many colors there are Slide 7 Why we don’t know how many colors there are Slide 8 Why we don’t know how many colors there are Slide 9 Why we don’t know how many colors there are Slide 10 Why we don’t know how many colors there are Slide 11 Why we don’t know how many colors there are Slide 12 Why we don’t know how many colors there are Slide 13 Why we don’t know how many colors there are Slide 14 Why we don’t know how many colors there are Slide 15 Why we don’t know how many colors there are Slide 16 Why we don’t know how many colors there are Slide 17 Why we don’t know how many colors there are Slide 18 Why we don’t know how many colors there are Slide 19 Why we don’t know how many colors there are Slide 20
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Why we don’t know how many colors there are

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There have been many attempts to answer the question of how many distinct colors there are, with widely varying answers. Here we present an analysis of what it would take to arrive at a reliable answer and show how currently available models fail to make predictions under the wide range of conditions that needs to be considered. Gamut volumes are reported for a number of light sources and viewing modes and the conclusion is drawn that the only reliable data we have comes from psychophysical work. The color gamut of the LUTCHI data in CIECAM02 is therefore shown as an alternative to the gamut of all possible colors.

Why we don’t know how many colors there are

  1. 1. Why we don’t know how many colors there are Ján Morovič, Vien Cheung* & Peter Morovič Hewlett-Packard Company *University of Leeds Presented by Dr. Vien Cheung at CGIV ‘12, Amseterdam on 7th May 2012 CGIV 2012
  2. 2. How many colors are there? 28 × 28 × 28 = ~ 16.8 million 3 infinity
  3. 3. How many colors are there? o  interesting! o  usefulness in engineering decision processes o  but ... what is color? and what does ‘all possible colors’ mean?
  4. 4. What does ‘all possible colors’ mean? 16 million | 2-10 million CIE system | visual system physical colors | perceptual colors
  5. 5. Color illusions o  the notion of color is essentially a property of an object does not explain color illusions
  6. 6. Color ‘illusions’ [255 0 0] physical colors > perceptual colors physical colors < colors depend upon context
  7. 7. Related studies 2010 Maric-France & Foster 2008 Linhares et al. 2005 Heckaman et al. o  natural surface 2004 Inui et al. o  color spaces | gamut computations 2001 Morovič et al. o  viewing condition 1999 McCann o  illumination | adapted white 1980 Pointer o  natural scenes o  all possible surface colors 1920 Schrodinger
  8. 8. Our work o  counting all possible colors ‘by hand’ o  computationally predicting all possible colors o  discuss the limitations of gamut computation and appearance prediction
  9. 9. Counting colors ‘by hand’ o  this exercise can tell us how many colors there are on a gray background, when viewed under a certain light source, etc.!
  10. 10. Counting colors ‘by hand’
  11. 11. Computational prediction o  an ecosystem enabling varying color experiences o  CIECAM02 o  color appearance attributes  effect on predicting gamut o  explore the effect of various model parameters
  12. 12. Computational prediction
  13. 13. Computational prediction Light source D50 F11 Surround average dim dark average Background 20% 20% 20% 20% Luminance of ~60 cd/m2 ~60 cd/m2 ~60 cd/m2 ~60 cd/m2 adapting field Gamut volume 3.8 MJab 3.5 MJab 3.0 MJab 4.2 MJab o  D50 + F11 = 4.4 MJab o  D50 + F11 + A (3.5 MJab) = 4.5 MJab
  14. 14. Computational prediction o  expanding to standard iluminants to freely varying their SPD o  242 synthetic light sources 0.9 0.8 0.7 0.6 11 log10 Jab gamut volume 0.5 10 CIE y 9 0.4 8 0.3 7 0.2 6 0.2 0.1 5 0.4 0.1 0.2 CIE x 0 0.3 0.4 0.6 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.7 0.8 CIE y CIE x
  15. 15. Computational prediction o  CIECAM02 dramatically predicts color gamut with 1011 volumes in Jab space o  i.e. 100,000 times of all possible surface colors under D50 o  however, this increment does not agree with experience and is a psychophysical data-based model o  the difficulty of viewing all possible visual ecosystems remains
  16. 16. Computational prediction o  a revised prediction uses 173 measured light sources 1 0.9 0.8 0.7 relative spectral power 0.6 0.5 0.4 0.3 0.2 0.1 0 400 450 500 550 600 650 700 wavelength (nm)
  17. 17. Computational prediction 0.5 11 0.4 10 log10 Jab gamut volume CIE y 0.3 9 8 0.2 7 6 0.1 0.2 5 0.4 0.1 CIE x 0.2 0.3 0.4 0.6 0 0.5 0.6 CIE y 0.7 0.8 0.1 0.2 0.3 0.4 0.5 0.6 0.7 CIE x o  a total gamut volume of 6.6 MJab o  i.e. the surface, which under D50 (3.8 MJab), result in ~2× that range of colors viewed under a variety of light sources
  18. 18. Computational prediction 200 200 150 150 100 100 50 50 CIE b* CIE b* 0 0 −50 −50 −100 −100 −150 −150 −200 −200 −200 −150 −100 −50 0 50 100 150 200 −200 −150 −100 −50 0 50 100 150 200 CIE a* CIE a* D50 | 173 measured light sources 120 120 100 100 80 80 CIE L* 60 CIE L* 60 40 40 20 20 0 0 200 200 150 150 100 100 50 50 200 200 0 150 0 150 CIE b* 100 CIE b* 100 −50 −50 50 50 −100 0 −100 0 −50 −50 CIE a* −150 CIE a* −150 −100 −100 −150 −150 −200 −200 −200 −200
  19. 19. CAM o  Note that CIECAM02 does not include many complexities of colour vision such as contrast effects o  using CAM to indicate all possible colors should consider the color gamuts of colour appearance they are derived from o  CIECAM02 (LUTCHI data) – 1.7 MJab
  20. 20. Conclusions o  based upon the available data to-date there are at least ~1.7 million colors o  to go beyond this type of number would require: o  a color appearance model closely mimics the human visual system o  extend psychophysical basis
  • pmorovic

    Jul. 2, 2012

There have been many attempts to answer the question of how many distinct colors there are, with widely varying answers. Here we present an analysis of what it would take to arrive at a reliable answer and show how currently available models fail to make predictions under the wide range of conditions that needs to be considered. Gamut volumes are reported for a number of light sources and viewing modes and the conclusion is drawn that the only reliable data we have comes from psychophysical work. The color gamut of the LUTCHI data in CIECAM02 is therefore shown as an alternative to the gamut of all possible colors.

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