Anyone else think 1931 is rather long ago?

In 1931 there were no LEDs, no lasers, no computers, and photo-electric technology was in its infancy. To the best of my knowledge diffraction gratings and dichroic filters weren't readily obtainable either.

 

Since 1931 the general standard of human nutrition has also improved dramatically.

 

And yet, the year 1931 is apparently the most recent that human perception of colour was "standardised" by the Commission Internationale de l'Eclairage. Said CIE have apparently been sitting on their corporate backsides over the matter ever since.

 

There seems to be no record either of the size or ethnic mix of the sample of people used to derive the CIE "horseshoe", but I'd like to bet it was mainly White Europeans.

 

Time for a retest using modern technology and a sample truly representative of human ethnic diversity?

 

I surely think so. What about you?

Perhaps the CIE "horseshoe" is as basic as 2+2=4, and ethnicity has nothing to do with it. There's also the CIELUV of 1976:

 

CIELUV - Wikipedia

You bring up an interesting question. I suspect that there is more variation in color perception among individuals of one race than average differences between races. It brings to mind the old question, "do you see red the same way that I see red?". A question that is hard to quantify.

 

I find one study titled, "Racial differences in color vision: do they exist?" at Racial differences in color vision: do they exist? - PubMed - NCBI . The study concludes that "Results indicated that pigment (i.e., racial) differences in color vision do not exist, as measured by the two psychophysical methods used." I have only read the abstract, so I can't comment further on the study.

Pigments in the eye, responsible for color vision, can be isolated and objectively analyzed. Perception, on the other hand, is the way your brain interprets these signals. It is unlikely that visual pigments vary between races or individuals. Perception involves many factors, which are difficult to measure. There are physical factors as well. Cataracts absorb blue to the extent your perception of color can be grossly distorted. Paintings of Claude Monet became increasingly blue in his later life, probably in compensation for his cataracts. There are also genetic defects which affect development of the color-sensing mechanism. The frequency and extent of these deficiencies vary between populations, and presumably race. Damage to one or both occipital lobes of the brain can affect color perception, even if the retina is normal.

 

Environment and culture probably affect color perception. Nor is this effect limited to color. We tend to hear and understand that which reinforce our personal biases. Eye witness accounts of the same events can vary widely. News reports of political speeches often bear little resemblance to the actual transcripts.

I read that Claude Monet had cataract surgery (in the early 1900's!) for one eye, but not the other. He wore a patch over the other eye which eliminated his stereoscopic vision. Henceforth, his subjects tended to be more two dimensional as well as blue.

 

There was an update to the CIE chromaticity diagram in 1964 to account for the obsever's field of view. From Wikepedia, CIE 1931 color space - Wikipedia,

"Due to the distribution of cones in the eye, the tristimulus values depend on the observer's field of view. To eliminate this variable, the CIE defined a color-mapping function called the standard (colorimetric) observer, to represent an average human's chromatic response within a 2° arc inside the fovea. This angle was chosen owing to the belief that the color-sensitive cones resided within a 2° arc of the fovea. Thus the CIE 1931 Standard Observer function is also known as the CIE 1931 2° Standard Observer. A more modern but less-used alternative is the CIE 1964 10° Standard Observer, which is derived from the work of Stiles and Burch,[7] and Speranskaya."

 

I would guess that the 10° standard observer would be more applicable to photography than the 2° since most photographs cover a wider field of view.

Edited August 21, 2017 by Glenn McCreery

1964 is still a long time ago, and the 1976 CIELUV was derived directly by mathematical transform from the 1931 data as I understand.

 

Leaving aside any ethnic variance, there's still the issue that nutritional changes could well impact colour vision. As they have stature and general health.

 

However, the main concern must be that 1931 (or 1964) technology simply didn't allow the degree of accuracy that could be achieved today.

 

In 1931 I imagine that a prism monochromator set in front of an incandescent lamp or arc source and compared with some crude gel filtered RGB sources controlled by 3 rheostats was considered state of the art. And goodness knows how any objective control response was measured or servoed.

 

Sorry, but that ancient methodology just wouldn't wash today.

If it ain't broke, don't fix it.

I would be in favor of repeating and updating the 1931 tests with modern equipment, especially if the test participants were of too narrow a range of differences. I would not be surprised if they were all university students, which would imply that they were young, healthy, and mostly male (especially in 1931).

 

An updated CIE chromaticity diagram should have uncertainty bands, or a list of uncertainties, not just sharply specified regions.

 

Updating a well established standard is never easy. We in the U.S. are still using the British system of inches and feet for building materials when the rest of the world, including Britain, has gone to S.I. (metric).

"If it ain't broke, don't fix it."

 

- Except how do we know it ain't broke?

They didn't even have the jet engine or anti-reflection lens coating in 1931, and some thought Adolf Hitler was a decent chap.

You understanding of what's happened since 1931, based solely on that set of data is lacking.

 

The work of the CIE in 1931 is all about color perception, not color appearance and the later has been worked on for years! And it is vastly MORE complex to understand! This original work was never, ever designed as a color appearance model. It was never designed to even be used as an interchange space between device dependent color models. It's not designed for imagery at all. It's all based on solid colors in very specific ambient and surround conditions.

 

Colorimetry and the dE testing is about color perception. It is not about color appearance. The reason why viewing a print is more valid than measuring it is because measurement is about comparing two solid colors. Which is what the work of the CIE is based upon back in 1931. It's not perfect and has been updated since (probably most recently in 2000 with updated dE formulas). Color appearance is about evaluating images and color in context which measurement devices can't provide. Again: Colorimetry is about color perception. It is not about color appearance. Colorimetry based on TWO solid colors in very specific ambient and surround conditions. This is the means of which the CIE produced it's initial work back in 1931.

 

Go out and get a copy of Mark Fairchild's book on color appearance, you'll get an updated idea of what's radically changed in our understanding of color since 1931.

Wiley: Color Appearance Models, 3rd Edition - Mark D. Fairchild

Beyond the locus of spectrally pure colors

Mark D. Fairchild*
Munsell Color Science Laboratory, RIT, Rochester, NY, USA 14623-5604

 

The spectrum locus of a CIE chromaticity diagram defines the boundary within which all physically realizable color stimuli must fall. While that is a physical and mathematical reality that cannot be violated, it is possible to create colors that appear as if they were produced by physically impossible stimuli. This can be accomplished through careful control of the viewing conditions and states of adaptation.

 

The CIE 1931 xy chromaticity diagram is widely recognized by the horseshoe shape of the spectrum locus. This locus of spectrally pure colors is simply defined by the standard color matching functions, the computation of chromaticity coordinates, and the fundamental limitation of monochromatic stimuli that have energy at a single wavelength and no energy at any other visible wavelength.1 More commonly, the spectrum locus is referred to as defining the boundary of the gamut of all physically possible colors. This, however, is an error. The spectrum locus does define the gamut boundary for physically possible stimuli, but it does not limit the color appearance of stimuli. Specification of color appearance requires more information about the stimulus and adaptation state of the observer2 and it is entirely feasible that a stimulus in one viewing condition might appear to be produced by a stimulus from beyond the locus of spectrally pure colors in some other reference viewing condition.

" horseshoe shape of the spectrum locus."

 

A locus is a single point and cannot have a shape.

 

Regardless of the above gobbledegook.

 

The objective mapping of human colour perception is necessarily limited by stimuli that can be physically produced, and not by imaginary stimuli that cannot.

 

Technology has moved on since 1931 (you don't say?!), and enables us to produce brighter and purer monochromatic stimuli and more importantly, better RGB filters or sources for matching stimuli. While computer data handling allows automated gathering and rapid collimation and analysis of that data.

 

Photonics wasn't even a word in 1931, and photometry was in a comparative stone age. The technology was nowhere near mature and alike to trying to measure pico-seconds accurately without the aid of an atomic clock!

 

Going back to square one and doing the job properly with modern tools just wouldn't go amiss.

 

And I'm perfectly aware of the difference between colour perception and colour appearance. Nobody was talking about colour appearance or colour reproduction.

 

Do you not think the fundamental area (space) of human colour perception is important to have an accurate and up to date map of?

 

It may well be smaller, larger or differently shaped than the "here be dragons" map of ancient times.

Edited August 21, 2017 by rodeo_joe|1

Do you realise that if you perpetually tell a child, from a very early age, that red is green and green is red, not only will it believe you, it will also greatly perplex its school teachers. So the child is seeing the same colours as everyone, but just associating the incorrect names with them. How then can its colour perception be measured ?

" horseshoe shape of the spectrum locus."

 

A locus is a single point and cannot have a shape.

Regardless of the above gobbledegook.

Calling the work of Fairchild gobbledegook illustrates this is a topic you don't understand nor should you be taken seriously.

Worse is the very first person here who used the word, horseshoe: you! More reasons not to take your post here at all seriously!

 

There seems to be no record either of the size or ethnic mix of the sample of people used to derive the CIE "horseshoe", but I'd like to bet it was mainly White Europeans.

 

And I'm perfectly aware of the difference between colour perception and colour appearance.

Now I'm perfectly aware that you do not!

The reason there's so much ignorance on the subject of color management, is that those who have it are so eager to regularly share it!

Edited August 21, 2017 by digitaldog

"If it ain't broke, don't fix it."

 

- Except how do we know it ain't broke?

They didn't even have the jet engine or anti-reflection lens coating in 1931, and some thought Adolf Hitler was a decent chap.

They didn't even have the jet engine or anti-reflection lens coating in 1931, and some thought Adolf Hitler was a decent chap.

The earliest reference to anti-reflective lens coating was in 1822 by Taylor Cook, inventor of the eponymous Cook Triplet.

 

A Brief History of Optical Coatings

 

Hitler didn't fool most folks, with the notable exception of Neville Chamberlain, Charles Lindberg, and Joseph Kennedy, father of John F Kennedy. They remained fooled until 1939.

The earliest reference to anti-reflective lens coating was in 1822 by Taylor Cook, inventor of the eponymous Cook Triplet.

We will probably now be told it's just:

gobbledegook

:cool:

The bit about Hitler originally posted is yet another data point that the original poster isn't to be taken too seriously.

We were asked: I surely think so. What about you?

I now do believe the OP has an agenda to have us post what he wants to hear....

The principles of anti-reflection coatings go all the way back to the 16th century, from the work of Willibrord Snellius (scientists latinized their names in the Renaissance), who reflected {pun intended) on studies by Ptolomy, two millennia earlier. Snellius' Laws of Refraction go well beyond concepts introduced in high school physics. Among these is the simplified concept that light not reflected from an optical surface is transmitted. Think "conservation of momentum." Snellius also delved into reflections from metals, which led to metallic filters (used widely in spectrophotometry) and dichroic heat absorbing glass. We spent two weeks on Snellius' Law in quantum mechanics (graduate school).

 

Snell's law - Wikipedia

Willebrord Snellius - Wikipedia

 

Photographers in the 19th century experimented with metal deposition (e.g., mercury and tin) as well as flame treatment to oxidize the surface, to improve the transmittance of lenses. Karl Zeiss pretty much nailed it in the 1890s with dielectric coating.

 

I studied gobbledygook for credit ;)

Edited August 22, 2017 by Ed_Ingold

" horseshoe shape of the spectrum locus."

 

A locus is a single point and cannot have a shape.

 

.

 

 

Not so,

 

the definition of locus

 

"Mathematics. the set of all points, lines, or surfaces that satisfy a given requirement."

You're of course correct bgelfand!

Easy to find this on 'the google" :D

 

lo·cus

ˈlōkəs/Submit

noun

1.technical

a particular position, point, or place.

"it is impossible to specify the exact locus in the brain of these neural events"

More to this topic of which some here consider gobbledegook:

 

2. MATHEMATICS

A curve or other figure formed by all the points satisfying a particular equation of the relation between coordinates, or by a point, line, or surface moving according to mathematically defined conditions.

 

Facts one** here considers due to ignorance, gobbledegook:

In color spaces which include all, or most spectral colors, they form a part of boundary of the set of all real colors. If luminance is counted, then spectral colors form a surface, otherwise their locus is a curve in a two-dimensional chromaticity space.

 

"The highest form of ignorance is when you reject something you don't know anything about". -Wayne Dyer

 

**Here's all we know about Rodeo Joe (no transparency, probably not a real name):

Rodeo Joe | photo.net

 

Here's what we know about Dr. Mark Fairchild, the so called author of gobbledegook by someone who appears to know more about rodeo's than color science:

 

RIT College of Science | Mark Fairchild

Dr. Fairchild has been a faculty member in the Program of Color Science / Munsell Color Science Laboratory since 1986 and achieved the rank of Professor in 1999. He received his B.S. and M.S. degrees in Imaging Science from R.I.T. and Ph.D. in Vision Science from the University of Rochester. He also serves as the Director of the Ph.D. Program of Color Science and Munsell Color Science Laboratory, roles he held from 1996-2007 and 2013-present. He is author or co-author of over 300 technical publications in color and imaging sciences and the books, Color Appearance Models, 3rd Ed. (2013), which serves as a reference to the fundamentals of color appearance and the formulation of specific models and the Handbook of Color Psychology (2015) as well as 3 websites related to color and science education. He has received 8 best-paper awards from various conferences. He has supervised the graduate research of 59 M.S. or Ph.D. students.

 

https://scholar.google.com/citations?user=3lQS8Y4AAAAJ&hl=en&oi=sra

 

So who do you want to listen to about the science of color?

The nomenclature of colours (red/green or green/red) is irrelevant when objectively measuring human eye response to wavelengths.

 

Perception of colour, or the visual part of the electromagnetic spectrum, can be divided into 3 parts by increasing difficulty of measurement and complexity of methodology.

 

1. Bandwidth from Lambda min to Lambda max. I.e. the shortest wavelength that causes a sensation of colour, to the longest. Or vice versa. There will obviously be variation by luminous intensity - weighted power level of light, and possibly by gender, age, or ethnicity of subject. Naming of colours has no bearing on this measurement.

 

2. Colour discrimination or Delta-Lambda. I.e. the smallest shift of wavelength that can be detected by eye. Variation by luminous intensity, etc can be expected here as well. Here too, there is no need to name the colours being compared.

 

3. Measurement of response to or recognition of saturation, which could be defined as how "diluted" or polluted by white light a monochromatic source can be before it's recognised as differing from truly monochromatic. Or alternatively, how far the frequency of light can be widened before it's perceived as differing from monochromatic. Variance by subject and luminous intensity should also be expected here.

 

Unless by some wild chance all of the subjects show an identical response; it should be expected that the colour space of human vision will vary from some maximum to minimum set of values. Even excluding those subjects with a recognised colour vision deficiency or abnormal extended sensitivity. No such parameters are shown or mentioned in the CIE "hard and fast" colour map.

 

FWIW. The technology to repeatably and reliably manufacture anti-reflection coatings on lenses was not developed until well after 1931. Previous reports of AR coatings refer to accidental chemical or age induced surface modification of the glass itself. Not a purposeful deposition of a separate dielectric material.

 

Mr Rodney. If you can't contribute anything except nit-picking and deliberate misconstruction of my posts; then please uninvite yourself from making further "contributions".

 

The Latin word "locus" BTW, means "a place" singular. If mathematicians choose to appropriate that word to mean "a line joining a number of places" then that shows their poor understanding of classic languages.

Edited August 22, 2017 by rodeo_joe|1

The nomenclature of colours (red/green or green/red) is irrelevant when objectively measuring human eye response to wavelengths.

 

Perception of colour, or the visual part of the electromagnetic spectrum, can be divided into 3 parts by increasing difficulty of measurement and complexity of methodology.

 

1. Bandwidth from Lambda min to Lambda max. I.e. the shortest wavelength that causes a sensation of colour, to the longest. Or vice versa. There will obviously be variation by luminous intensity - weighted power level of light, and possibly by gender, age, or ethnicity of subject. Naming of colours has no bearing on this measurement.

 

2. Colour discrimination or Delta-Lambda. I.e. the smallest shift of wavelength that can be detected by eye. Variation by luminous intensity, etc can be expected here as well. Here too, there is no need to name the colours being compared.

 

3. Measurement of response to or recognition of saturation, which could be defined as how "diluted" or polluted by white light a monochromatic source can be before it's recognised as differing from truly monochromatic. Or alternatively, how far the frequency of light can be widened before it's perceived as differing from monochromatic. Variance by subject and luminous intensity should also be expected here.

 

Unless by some wild chance all of the subjects show an identical response; it should be expected that the colour space of human vision will vary from some maximum to minimum set of values. Even excluding those subjects with a recognised colour vision deficiency or abnormal extended sensitivity. No such parameters are shown or mentioned in the CIE "hard and fast" colour map.

 

FWIW. The technology to repeatably and reliably manufacture anti-reflection coatings on lenses was not developed until well after 1931. Previous reports of AR coatings refer to accidental chemical or age induced surface modification of the glass itself. Not a purposeful deposition of a separate dielectric material.

 

Mr Rodney. If you can't contribute anything except nit-picking and deliberate misconstruction of my posts; then please uninvite yourself from making further "contributions".

 

The Latin word "locus" BTW, means "a place" singular. If mathematicians choose to appropriate that word to mean "a line joining a number of places" then that shows their poor understanding of classic languages.

 

Pure gobbledegook.

Unless by some wild chance all of the subjects show an identical response; it should be expected that the colour space of human vision will vary from some maximum to minimum set of values.

Studies of this sort use biometric statistics, which accounts for variations and produces defendable results with an estimate of uncertainty. Applying analysis of variance (ANOVA), you can accurately estimate variations between various populations as well as individuals in repeated experiments, as well as the overall uncertainty. The generic process is called Experimental Design - aka Statistics 401.

Edited August 22, 2017 by Ed_Ingold

I'm sorry, but I'm finding it very difficult to take any of the discussion on this thread seriously when all the authors seem ignorant of Crosley Bendix's pioneering work on colour perception theory, which makes CIE 1931 and all its derivatives completely obsolete: Squant