Hue & Saturation doubt

[KronoX]

Good morning,

I was reading the tutorial named: "COLOR PERCEPTION"
(https://www.cambridgeincolour.com/tu...perception.htm)

In the last section "COLOR PROPERTIES: HUE & SATURATION", is said

Hue: describes which wavelength appears to be most dominant.
Saturation: is a measure of the its purity

But, in the hue explanation, it also says:
"If this object instead had separate and pronounced peaks in just
the the red and green regions, then its hue would instead be yellow"
Here is my doubt: what would be the "Saturation" of such spectrum?

Sorry if I'm misunderstanding something, and thank you in advance.

Regards.

[dem]

The saturation depends on how high the peak is with respect to the background (the base line).

At the end of that page it says: "A highly saturated color will contain a very narrow set of wavelengths and appear much more pronounced than a similar, but less saturated color". And there is an interactive example.

What I did not understand though is how this information can be useful to anyone.

[xpatUSA]

Good morning,

I was reading the tutorial named: "COLOR PERCEPTION"
(https://www.cambridgeincolour.com/tu...perception.htm)

In the last section "COLOR PROPERTIES: HUE & SATURATION", is said

Hue: describes which wavelength appears to be most dominant.
Saturation: is a measure of the its purity

But, in the hue explanation, it also says:
"If this object instead had separate and pronounced peaks in just
the the red and green regions, then its hue would instead be yellow"
Here is my doubt: what would be the "Saturation" of such spectrum?

Sorry if I'm misunderstanding something, and thank you in advance.

Regards.

The best explanation I've read is the Wikipedia, in particular this section:

https://en.wikipedia.org/wiki/HSL_an...ing_attributes

Saturation is kind of like Chroma (how colorful something is) but is not quite the same:

https://en.wikipedia.org/wiki/HSL_an...and_chroma.svg

Saturation in our context usually refers to that given by the HSB model as found in Photoshop.

In the HSB model, Chroma gets scaled to fit into the model and is simply Saturation = Chroma (C)/highest value of RGB (M), i.e. S = C/M. Now Chroma itself = the highest value of RGB (M) minus the smallest value of RGB (m) i.e. C = M-m.

So now, combining the two formulae, we get Saturation = (M-m)/M.

Now we can calculate "the 'Saturation' of such spectrum"

Back to CiC's color with two peaks in red and green and some lower value for blue, say R,G,B = 210, 150, 10. For Saturation that comes to (210-10)/210 = 0.95 = 95% saturated.

There you have it

As to usefulness, Dem:

From that formula we can see that, if any of R,G,B is zero, the color is 100% saturated. This knowledge is useful for seeking out saturation-clipping in flower shots.

Also from that formula, we learn that saturation is independent of the 'brightness' of a color - for example R,G,B = 0,1,1 is 100% saturated but probably looks black on your screen. This knowledge is useful for those unfamiliar with color in general and in particular for those who think that the brighter a color is, the more saturated it is.

[KronoX]

Sorry for not answering before, I just realized I got answers to my thread.

Thanks to both for your replies.

Now, I'll start reading the info in the links you passed me.

[KronoX]

Sorry for answering late. I just realized I got answers to my thread.
Thank you, both, very much.
Now I will start reading the recommended information