Color Vision 2: Color Matching
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- เผยแพร่เมื่อ 24 ก.ค. 2024
- The science of color is based on Color Matching, the ability to match any color using 3 basic colors, red, green and blue. Results of color matching lead through color space, to a color map called the Chromaticity Diagram. That defines a standard way to specify color, and is very useful for understanding how color works and color vision. Number 2 in series about Color Vision.
- วิทยาศาสตร์และเทคโนโลยี
10 years later and this is still one of the best series on internet describing color, amazing, thank you for sharing this great knowledge with us.
On behalf of the University of Waterloo School of Optometry, thank you for helping us understand this concept!
some things never change
This is a great explanation. I've been reading stuff about the CIE xyz colour model for a few days and I didn't really understand the negative red values and how 'imaginary colours' arise until I came cross this video. Thank you so much.
This is possibly the most accessible and also elaborate explaination of these concepts you will find online.
This should be required viewing for people like me who are trying to understand color science for working with modern video format and colour grading.
All videos on topic of color vision are just awesome. I have looked for more than 75 articles and various videos but your explanations are easy to understand and simply the best. Thank you for sharing your knowledge.
this is absolutely a brilliant explanation...I read a book about the CIE diagram...I could never figure it out....this video clears it up! thanks for uploading this!!!!
Oh my God this is the best explanation of color I've seen so far! Fascinating!
I've been researching this topic for weeks and this is one of the best videos I've seen so far!
This is by far the best explanation of the Yxy model I've come across since forever.
Literally the best explanation of colour matching on the internet!
Thank you!
Great explanation! I learned and understood a few things about color matching and color that I didn't before!
Thank you for your great work here!
Great video
Just wow! I spent several weeks trying to understand this subject and the different aspects of it didn’t quite tie in together. Till I watched this video. Thanks a bunch. Now I think I’m better prepared for my finals!
as every one else, a very warm thank you. You make it sooooo much clearer! Great explanations
this is an excellent presentation of some tough concepts. I've been trying to get my head around this stuff recently and your video has really furthered my understanding. Looking forward to part 3 :)
Perfect explanations! Very grateful for all the work input, it surely helped a lot :)
Excellent explanation... this same thing took me around 2 hours to understand by reading... Thank you.
Incredibly helpful. Thank you very much!
Thank you! Especially for the explanation of negative part of the 'r'...
This is a life saver, thank you for your work
Awesome and easy explanation. Thank you!
This is a great explanation of my favorite subject : color
Thank you 💖
Wow....what a wonderful teacher...Thank you very much..........A great way of explanation...
wow, I can actually understand the diagram now! thank you for the great video
When we see the locus graph, is it as if we're seeing the 3d triangle chart side on? If so then I don't get why the diagonal base doesn't aim for the xy zero point. Or is it because it's being adjusted back due to the negative color thing?
To be honest the negative color thing doesn't really make sense to me either but I guess it's ultimately down to a perception thing (we don't have equally spaced RGB color receptors in our eyes) and I'll blame nature.
So, in order to get these blue-green colors outside of RGB space, we need additional blue and green light sources at their wavelengths being closer to that part of the gamut?
wow! Thank you so much for sharing these videos.
Fantastic video Craig!
That is correct. Picture a triangle inscribed within a circle. There will always be uncovered regions.
However, for TV and computer monitors it turns out we don't seem to notice the missing colors.
Sir, may I please know if there is any mathematical modeling done to get this tristimulus values?
Exactly what i needed, thank you so much!!
Question. Why do some devices go outside of the RGB triangle?
Very good explanation. A good resource who works in Lighting Technology
It would be a wonderful image for understanding if the spectrum shown on 3:37 could be put under the curves on 3:59. (All on the same image). For even quicker understanding. Very good lectures! Thank you
Excellent explanation. Thanks you !!
Very informative, thank you very much! :-)
and could you please make a video or suggest me some reference material to understand the Munsell color system?
If monitors used 530 nm or 525 nm green, wouldn't that improve the range of colors that can be displayed substantially?
excellent set of videos!
Wow, I'm wondering why purple lies so close to blue in the chromaticity diagram. It seems that just a little bit of red is sufficient to create purple from blue, which is not the case, when I add R and B in RGB.
So, the colors I see on my screen, outside of the RGB triangle on the CIE map, which can not be recreated by RGB combinations, are not the true map colors? As my screen is RGB?
Awesome video! Thank for sharing
You have save me!! Great video.
+Rachel Exler lol
Thanks for this contribution!
Looking at the chromaticity diagram, why not change the value of pure green to 520 manometers? Wouldn't this significantly expand the number of colors that can be generated by mixing pure red, blue, and green? What am I missing here?
So why do we only use red, green and blue to reproduce colours when it can't completely recreate cyan? Surely if we used a 4th cyan coloured light, then we would get closer to the full range of colours, right? Or even 5 lights to get close to the shape of the chromaticity diagram.
Thanks for this great video! Why do you still label XYZ axes as red/green/blue? Aren't XYZ transformed from RGB, thus different than RGB?
If you are given the X and Y cordinates, how do you work out Z?
I need an example of metamerism with the cie, but i cannot find any. can someone help
Great video. Thanks!
Thank you. This was very helpful.
A well informative video. But sir, can this concept be used to select which color goes well with each other ?
Thank you! It helped me a lot!
what does the module of the vector mean?
what about violet?? why did he grouped it with blue like if they were the same???
Thanks for the video. Does this means that the monitors, that mix light from red, green and blue pixels, can't represent all spectrum of visible light? Thanks again.
Exactly. Most can't even represent all colors of the standard RGB (sRGB) space.
best explanation! thank you
Hello! I have a hard time understanding the tristimulus chart. I thought the CIE diagram was based on the normalized responsivity spectra of human cone cells, not on the linear combination component values of a wavelength onto the 700 nm, 546.1 nm and 435.8 nm. Or are they the same thing? And why is the tristimulus chart negative? And why those particular wave lengths?
Thanks!
thank you for this video!
Awesome explanation.
Thank you. Really helpful.
Great video! love from UW optometry! :) thanks
Actual Life Saver
Hi. Very informative vidoe.. my final year project is based on this and i'd love to read more about this.. is there a book you recommend to understand color spaces in general?
Thank you so much I really needed it ♥️♥️
Thank You. It was helpful
Thanks, great explaination
Thank you so much I really needed it
really great and helpful video
helpful and informative. i have a couple of questions if someone cares to answer:
1. Why does the spectral locus look the same in the unit plane and in the XY graph later on
2. why is it the adding colors represented by chromaticity points on the chormaticity diagram will result in a color that is in between the line joining the two points
To answer your second question, it's just how linear combination works. Let us assume you have two points: (x₁, y₁, z₁) and (x₂, y₂, z₂). Now you have the conditions:
x₁ + y₁ + z₁ = 1
x₂ + y₂ + z₂ = 1
and adding them together yields
x₁ + x₂ + y₁ + y₂ + z₁ + z₂ = 2.
Now if you divide by 2 you get (x₁ + x₂ + y₁ + y₂ + z₁ + z₂)/2 = 1, which shows that adding the points and normalizing the sum is the same as taking the midpoint of the points.
How exactly did you go from RGB into XYZ into xyY? What is physical interpretation of all those axes? OK, RGB values are intensities of light reflectors. You could have drawn a 3D figure of visible light in that color space (disregarding reds being negative) and then went on explaining from there?
Some complexity here. There are several steps in the process of converting real RGB stimulus values into the useful, but imaginary, XYZ system. Transformation reasoning and equations can be found in detail in the classic text, Wyszecki and Stiles (Color Science, 2nd ed), section 3.2.5. Judd (Color in Business, 1975) has a friendlier, but less detailed explanation. (In a good library near you?)
Yes I have those transformations and I'm watching them. Correct me if wrong.
1. Y was chosen to match luminosity and X and Z were "pulled away" so that XYZ space could envelope the whole visible spectrum with coordinates for all visible colors (and even some more) being positive. What confuses me is jump into xyY. It should be just a slice for X+Y+Z=1? But if Y is luminosity, how come we have color information upwards the Y axis? Why don't we have a chromaticity diagram in X-Z plane, but we go up in X+Y+Z=1 plane?
2.If cyan color was the problem for color matching experiment, so we had to add negative red, and our solution was to drive blue and green into imaginary supersaturation, we ended up in XYZ where X, Y and Z represent super-saturated red, green and blue, how come Y only carries luminosity and no chromaticity data?
3. OK, the intersection of that plane (X+Y=Z=1) and our visible color space forms a basic version of chromaticity diagram? Why don't we use it as is?
4. Is there a special reason we project it on XY plane, and not on XZ? Or, in other words, what would be the fundamental difference in xzY against xyY?
Thanks for understandable explaination
Surely if we can't represent the full gamut of human vision with RGB, that must mean we chose inadequate primary colours? If we used the same primaries as our cone cells detect, wouldn't we be able to match any colour they can perceive?
Unfortunately no. The gamut in XYZ space is cone-shaped, so there's no way to position three real colors as primaries inside the gamut such that all other colors can be mixed with positive-only coefficients. I'm not sure how to relate this to how our eyes detect color, though. Maybe it has something to do with the response curves not being symmetrical around their maxima?
Lumpiluk Apparently it's something to do with the response curves overlapping. Such that it is impossible to stimulate one set of cells without also stimulating the others.
It is a really good explanation
Wonderful explanation
Thanks a lot
Great explains 😊😊
困惑了我很久，非常感谢
I dont understand why matching red(700nm) requires 0 red, shouldnt it peak there
Rad. Thank you.
Perfect！
Thanku soo much
Excellent
There is one thing I don't understand:
If our eyes can only react to R, G and B, and no combination of RGB can create cyan, how can we see it then? Can someone explain?
Yea I was also confuse at first, but then I assume he is referring to cyan at 500 nanometers, but not as a general cyan color.
He says that no linear combination of those wavelengths can give a cyan color experience, but our cones detect a range of wavelengths and not only three.
WOW AMAZING!!!!
Thank you very much appreciate you posting this online really helped me out.... Thanks again
wow.
Light bulbs do not look while to me. Even the ones people say are white.
Javian Brown you’re probably ‘colour blind’ as I am. Coloured filters are rubbish and if fed by a white light, will appear to not look as they’re meant too. Doctors are morons by the way:-)
wow
I thought I knew how color worked…
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Amazing video, thanks!