Many people don't seem to know that the lenses in the human eye start going yellow with age. By the age of 50 most people are looking at the world through yellow filters! I experienced this when having a lens replaced because of cataract. The new plastic lens was clear, and when I came out of the operating room, I could see that the dresses of the nurses (that were grey/white stripes before) were now blue/white when I looked at them with the new lens. With the yellow lens in my other eye they were still grey/white! A blue sky was now qite vivid with the new plastic lens, not so with the old yellow lens. I played about with Wratten filters to see how yellow my original lens was, but sadly I can't find the details any more, and nnow have two clear plastic lenses. I wonder how old the 'Standard Observer' was? Bob Frost
On Jan 14, 2020, at 8:42 AM, Bob-BTY via colorsync-users <colorsync-users@lists.apple.com> wrote: I wonder how old the 'Standard Observer' was?
Multiple ages! There is no single person used to produce the model we know of as the Standard Observer: Establishing Standard Observers In 1927, physicists John Guild and David Wright gathered subjects and performed a color matching experiment to determine how the average person perceives color. Subjects were asked to look through a hole and match each color in the spectrum by combining various intensities of red, green, and blue lights. The hole only allowed a 2 degree field of view (similar to looking at one's thumbnail from arm's length distance or equivalent to a 1.7cm circle from a 50cm distance) because of the belief that our color-sensing cones were located in a 2 degree arc in the fovea, a region of the retina. Note as well, the In 1964, the CIE defined an additional standard observer, this time based upon a 10 field of view; this is referred to as the 10 Supplementary Standard Observer. According to this site (verification necessary) https://medium.com/hipster-color-science/a-beginners-guide-to-colorimetry-40... <https://medium.com/hipster-color-science/a-beginners-guide-to-colorimetry-401f1830b65a> “In the 1920s two color scientists, W. D. Wright and J. Guild, each performed similar color vision experiments. Wright performed his experiment on 10 subjects, Guild used 7. Their results agreed with each other so well that they were combined by CIE to create the RGB color matching functions we’ve been discussing.” So if we inspect the actual history, we see that the Standard Observer is an ‘average’ of many samples just like D50 is a sample of many actual cases of data collection. Andrew Rodney http://www.digitaldog.net/ <http://www.digitaldog.net/>
Bob-BTY via colorsync-users wrote:
Many people don't seem to know that the lenses in the human eye start going yellow with age. By the age of 50 most people are looking at the world through yellow filters!
This is well characterized by the CIE 2006 physiological observer. See "CIE 170-1:2006 Fundamental chromaticity diagram with physiological axes - Part 1". <http://cie.co.at/publications/fundamental-chromaticity-diagram-physiological-axes-part-1> Basically there are two tables that characterize the lens optical density as it is affected by age, that are a linear equation approximation to measured data. Cheers, Graeme Gill.
participants (3)
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Andrew Rodney
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Bob-BTY
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Graeme Gill