Can not correlate RGB values to paint colors as outlined above.
RGB applies exclusively to the additive (emitted light) color space. RGB are the three channels of colored light that mix together to create a bunch of different colors. Additive color is emitted light beamed to your eyeballs. i.e. A television, a computer monitor.
Paint colors are the subtractive color space. Subtractive color is reflected light that bounces off an object and then to your eyeballs. i.e. A red ball, or paint color on a wall.
There are mathematical formulas to toggle between color spaces. And you toggle for different, very specific reasons. Here's a link to chart of said formulas: http://www.brucelindbloom.com/index.html?Equations.html
But the bottom line is RGB does not apply in any way whatsoever to paint colors because, again, you're talking additive vs. subtractive. Additive is emitted, subtractive is reflected. Essentially apples and oranges.
Paint companies started providing RGB and HEX values in the last two or three years in order to help people communicate about their colors as accurately as possible utilizing a wide variety of devices like computers, tablets, and smartphones. Communicating *about* colors using a variety of devices is not the same as physically choosing, using, and applying paint colors to the 3 dimensional built environment.
What you're reaching for is a formal color order system like Munsell or ACC, Acoat Color Codification System or NCS, Natural Color System. These systems provide a notation for each color.
Do not confuse a value like RGB or HEX with a notation from a formal color order system.
A majority of American paint color collections are based on the Munsell Color Order System but they DO NOT provide the notation. Examples are Sherwin Williams and Pratt and Lambert. Some DO provide the notation an example would be California Paints and Dunn Edwards and you can find the full Munsell notation in the fandeck index.
ICI/Dulux also known as Glidden from the Home Depot utilizes the ACC system. Here again you can find the full ACC notation in the fandeck index.
Did I mention do not confuse a value like RGB or HEX with a notation from a formal color order system?
If you have a NOTATION you can indeed use it as describe above. The notation will guide you on factors of hue/chroma/value and very often LRV Light Reflectance Value too. In other words, guide you to more red or less red, for example. Color experts and artists know how to use these 100+ year-old color systems in exactly this way.
In order to use these formal color order systems, you have to correctly understand the proper structure of color. Undertones are only relevant if the medium is spread at different rates. Many people have the whole undertone thing completely, totally and tragically WRONG.
If the medium (like paint) is not spread at different rates, then undertone is simply a subjective figure of speech. Undertone is NOT a measurable, plottable nor fully-controllable aspect or attribute of color. That is the reason these 100+ year old color systems do not include undertones.
When you are using color notations from a formal color order system and you are talking about more or less red, more or less yellow, more or less orange you are talking about OVERTONES - not undertones. Overtone speaks to degrees of hue bias. That's why the color systems each have their own custom color wheel. Or, if you've ever seen a random color wheel integrated with a clock or actual degrees it's about plotting OVERTONES.
The Munsell wheel below demonstrates said degrees of overtones according to its system of human perceptually based color order.
Hope the info helps.
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Room colors and mirrored chset on far side of bed. Also, sizeable bench
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