: How to convert RGB colors into CMYK (real paint colors)? How can I convert an RGB color into a real life color? If I mix equal amounts of red, green and blue paint together in real life,

@Smith574

There is an online service which calculates artist paint mix recipes from rgb values here: sensuallogic.com/paintmaker/OnlinePaintMixer.html
It works both with oil and acrylic paints.


And the brands they cover is:
Golden Heavy Body acrylics
Liquitex Heavy Body acrylics
Rembrandt Fine Artist Oil colours
Gamblin Conservation colours

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@Ogunnowo857

I think a good caveat to all these answers is to keep in mind that color management in the digital world is a "close enough" science. When you calibrate and profile a monitor, you're not getting an accurate plot of all 16+ million 24-bit RGB colors. You're getting an accurate plot of a very minor subset of those colors, with every other color between them interpolated to a 'best guess.' Even if you're working in 48-bit color, the monitor is still only providing 'best-guess' color, and in fact is having to guess even more due to the finer color depth.

So you'll run into inaccurate color representation when comparing specific 'real world' colors to the equivalent monitor colors all the time. Many times the inaccuracy will be very minor, but at times, it will be surprisingly inaccurate.

Factor into this the facts that humans don't all see color in the same way, and that each eye will have slight color-sensitivity variations, and we're talking about a very inaccurate science that has a lot of room to grow.

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@Cofer715

as an addition to what people are saying about light. Red, blue and green light do infact make white. the rainbow (R,O,Y,G,B,I,V) is infact a white light that has been separated via refraction and divided into the R,G,B colors. the other colors are the overlapping of two light colours

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@Ravi4787994

if I take equal amounts of red, green and blue paint in real life I
will never obtain the white color or some shade of grey


That does not seem true. You will actually get a dark shade of grey such as this one in the center (from the subtractive color model), also known as the imperfect black in CMYK:



As for your main question, i.e. “how do I know what will it look like”, a precise answer will require you to know more about the light, about the colour of your red, green and blue pigments and how exactly they mix. If you want to actually experience the colour, for instance see it on a screen, you will need a properly colour-calibrated pipeline (I suggest Abhay Sharma’s Understanding Color Management for an accessible book on the subject) and any piece of software that understands colourspaces.

However, if you only need an approximate answer, here is a little tip: the hue of the final colour will be the same as the one you see on screen (because for hue calculation it does not matter whether you’re doing additive or substractive colour mixing); if your colour is #ff7f00 or [255,127,0], which is orange on an RGB screen, then you know the final colour hue will be orange (albeit quite a dark one).

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@Cugini998

Real color is a quite complex subject. In essence color is something that happens somewhere between your cornea and brain. Simplifying this a bit color is what you sense when some photons interact with the three color sensing structures in your eye. Other definitions exist but they fail on many levels.

Photons can reach your eye trough many processes. They can reach your eye directly from the light source, or they can bounce on the way. When they bounce your actually seeing the color that the surface did not absorb. Whereas when you emit light you see what was sent unless something obscures the light on the way. The photon can also reach your eye trough other processes, some which are weird and obscure but that's another subject.

Because we have 2 primary systems for imaging in design, we also have 2 base models: additive and subtractive. One deals with emissive media like monitors. The other with reflective media like paper, but also works for things like stained glass. These models are inverses of each other: RGB is the inverse of CMY; mixing RG gives you Y and so forth.*

Manually mixing color has some other challenges. Your pigments may not react with each other chemically, or anything can happen. The pigments also need to be pure, and not have too big of a spread in what they remove from the spectrum as the eyes sensors overlap slightly. I find it extremely unlikely that you will find paint that fulfills this requirement easily.

It's also important that your lightning conditions need to be good as it affects how the subtraction happens. It's possible to design colors that change when you go indoors under artificial light, as compared to direct sunlight (This is called metamerism).

Now comes the mindblowingly hard part. In order to mix the right color you need to measure the colors. See, RGB values themselves are just signals; they do not represent colors without you knowing how the device displays the color. Each monitor behaves differently, and so do your pigments.

* Interesting fact: The ordering, RGB and CMY, are not mistakes. Any of the two colors in a triplet combined makes the corresponding color you didn't choose in the corresponding inverse triplet, so G + B = C and C - Y = G. The fact that the colors don't display as pure is because the computer tries to mimic available pigments, failing miserably.

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@Murray976

Converting to CMYK won't help you unless you find CMYK specific paint, which I'm not sure exists. Commerical paint manufacturers use a variety of non-standardized ways of expressing colour - so try this web based converter:
www.easyrgb.com
This will convert your RGB to a paint colour. That's the free option.

If you want to be really picky, you'll have to buy a pantone book:
www.pantone.com/pages/pantone/index.aspx
Last time I bought one it was about 0. Pantone is the industry standard for matching colour in printing. If you're trying to match a colour in a logo, ask for the brand guide as it will likely list the Pantone value for the colours in the logo. Every printer owns a Pantone book, and picky printers and designers replace them after a few years when they start to fade and discolour. This is how the design industry references specific colours. And your software should be able to convert an RGB colour to a Pantone colour. However, paint stores don't use this system of colour matching - so you'll still have to take your pantone book with you to visually compare to their paint chips, or to be scanned by their software.

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@Cofer715

RGB is an additive color model using light directly from its source before it is reflected off of an object. In essence, you start in darkness and because you are directly viewing the light source, the wavelengths can be added to each other to create colors.

CMYK and 'real life colors' both use a subtractive method to display color. In essence, you begin with light and the color wavelengths which are not absorbed by a pigment, object, etc. are then reflected into your vision as different colors.

Yes CMYK conversion will make this much more achievable but understand that your monitor's RGB color profile will display one color, while CMYK colors printed (or mixed!) can look very different depending on your lighting, substrate used, and pigments, among other things.

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