Do hues of color change linearly?

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Hello,
I am trying to set up a method of calibrating colors. My program will take an image as input, and compute the % of pixels that contain a range of a certain hue (yellow). In order to ensure that everyone gets the same user experience, I need to make sure that the images have their colors calibrated. Hence, I am wondering if the hue of a color changes linearly with another color. For example, if the hue of x changes by 1 degree, would the hue of y change by 1 degree?
thanks.

Accepted Answer

Image Analyst
Image Analyst on 11 Mar 2015
Well I would have thought everyone would have seen the dress as white and gold as I see it. But despite Photoshop saying that the "gold" has a red content twice as much as the blue, some people don't see it. They think the "gold" is black even after you show them how the green and especially the red content is so great. It's not neutral colored at all, not even close. But to be fair, the "white" does have a somewhat greater blue signal so it is somewhat blue, though mostly white. So not everyone sees color the same.
I do high precision calibrated color imaging all the time, as you can probably tell from my logo to the left. But I don't know what you mean by "hue of a color changes linearly with another color" Sure, you can add an offset to the hue channel to shift all the colors by the same angle, if that's what you mean. You'd have to take care to subtract 1 from those hues that ended up more than 1.
Run the attached demo. Below is one of the images it produces:
I hope it helps - unless you're one of those black and blue dress people, then you can go stick your head in the sand.
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John D'Errico
John D'Errico on 13 Mar 2015
He, he, he. Good thing I did not see blue. Whew!

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More Answers (2)

Image Analyst
Image Analyst on 13 Mar 2015
Marcus, any reply?
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seven_dwarves
seven_dwarves on 13 Mar 2015
Edited: seven_dwarves on 13 Mar 2015
Apologies for the slow response. I know that I can add an offset to shift all the colors and your demo is very helpful, but it does not answer my question.
Let's say I were to place a piece of paper with 3 different hue values of say 20/360 30/360 and 40/360 in a room with a yellow light and I take a picture of that paper. Obviously the hue values would change by a certain degree. In order to check the degree changed, I measure the hue value of just 1 color, say 20/360 for example. If this value changes to 25/360, would it be safe to assume that the rest of the values are offset by 5 degrees as well? And if not, is there a way to find the offset, considering I am only able to check one of those colors? This example is just for explanation, I know that ideally I should check all 3 hues for their change, but in my problem I am physically unable to check for all the different hues.
Thanks.
P/s: I am one of those black and blue dress people ;).
Image Analyst
Image Analyst on 14 Mar 2015
No. Absolutely not. The perceived color is the integral of the light spectral emittance times the spectral reflectivity of the object times the spectral responsivity of the 3 cones in the eye. Because you have 3 spectra multiplied and integrated to produce a single number (L, A, or b), you could have materials look different under one light source than they do under another. This is called metamerism (pronounced meh - TAM - er - ism). The classic examples are where two colors match under one light source but when the light source changes, the colors change to two different colors - like you said, the two hues do not change by the same amount.
For some examples of metamerism, see these pages:

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Star Strider
Star Strider on 13 Mar 2015
I contribute 25% of the people have a 4th cone and see colors as they are to have fun with! I can’t claim that there is a genuine physiological basis for it, however. Retinal neurophysiology is not my are of expertise.
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Star Strider
Star Strider on 13 Mar 2015
I share your scepticism.
I couldn’t find any references to more than trichromat vision when I searched PubMed. There are too many articles to search quickly, but an article in a 2012 issue of Discover online reported that there are tetrochromats, all thus far being women. (The gender predisposition is due to colour vision being X-linked, so random mutations leading to that would be most likely to show up in women.)
That leads me to believe that there may be more genetic variation in colour vision acuity than is commonly realised. The genetic studies I found were all oriented toward the etiology of colour vision defects, not variations in normal colour vision, so this could be an area of potentially valuable research for someone interested in the topic.
The ‘mach effect’ in colour vision is new to me, so I looked it up. For all those interested, ‘Does the Chromatic Mach bands effect exist?’ provides an explanation.
I saw ‘the dress’ as white and gold as well.
John D'Errico
John D'Errico on 13 Mar 2015
Edited: John D'Errico on 13 Mar 2015
I recall that it is mostly women who tend to be quad-chromats. Due to the chromosomal setup. If they inherit subtly different cones on each X chromosome, then they can be quad-chromats. My interest in the area was actually in the other direction, due to some playing around with color blindness.

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