like if you wanted to mix paint to get a color from a computer would you do the opposite of what the RGB value is? I’m confused
like if I wanted to take the RBG code R:99, G: 66, B, 33 wouldn’t it look more lightful than if I mixed paint into 1 part blue, 2 part green, 3 part red? how would you paint a color code?
Colours are wavelengths of light.
Shining light directly combines wavelengths. It is additive.
Colored paint absorbs the wavelength and reflect only part of it. It is subtractive.
I think hsl is the better computer color model
If you’re going this route, I highly recommend looking into and using OKLAB instead.
The problem with HSL/HSV is that it’s not perceptually uniform - if you only move HUE to change color, you will get different perceived brightnesses. This is important especially when procedurally generating color palettes, but also makes it harder to pick a color.
OKLAB solves that issue, and is designed to be uniform. Here is a great article about it, which is funnily enough IIRC a blog post that invented the color spectrum, that got noticed and eventually turned into a new industry standard.
Here is a picture that sums up pretty obviously what is the difference. This is a gradient that moves just the hue.
RGB is for pixels that generate their own light, you add the colors together
CMY is for reflective surfaces that keep certain parts of RBG and reflect others. You can’t work with RGB there because what is reflected is not RGB. There you subtract colors
RGB are the base colors for addative methods like light mixing. Think about pixels on a screen.
CMY are the base colors for subtractive methods like paint mixing. Think about printer ink.
paint and light are different. for light, you are adding colours in from black to make it brighter; for paint, you are subtracting colours from white to make it darker. thus, respectively, additive and subtractive colours.
here’s a quick and simple cheat sheet to help you out!
additive colours (screen pixels, LEDs):
- nothing = black
- red + green = yellow
- green + blue = cyan
- blue + red = magenta
- red + green + blue = white
subtractive colours (paint, prints, colouring pencils):
- nothing = white
- cyan + magenta = blue
- magenta + yellow = red
- yellow + cyan = green
- cyan + magenta + yellow = black
Paints absorb light really Red paint should be -#00FFFF so under white light the light becomes FFFFFF-00FFFF -> FF0000
Of course under blue light (0000FF) it becomes 000000
If you mix paints you end up with -FFFFFF which turns any light into 000000.
Basically consider paint a transformation when it comes to light rather than a source
It is the difference between additive mixing and subtractive mixing. When you mix colors on a screen with RGB, you add light. When you mix pigments on a physical medium, you subtract the amount of light reflected (because each paint absorbs most light except the colors it reflects, which are what you see).
As a side note, when mixing in the subtractive color system, your primary colors are cyan, magenta, and yellow. That’s why a printer takes CMYK, for cyan, magenta, yellow, and black. In case you were wondering, ‘K’ here is black.
K is key. It’s not necessarily black ink, but tends to be when printing on white stock.
If you’re printing on black stock, for instance, you’ll likely have white ink for the key.
Thank you for the correction.
Great explanation. Thank you.
Can you also tell me how a computer monitor makes Yellow when it only has RGB pixels?
Sure! On a spectrum of visible light, yellow has a wavelength between red and green. Therefore, combining red and green, the average wavelength is the same as the wavelength of yellow. In fact, a yellow pixel is really just a pair of red and green pixels on most monitors (except with certain types of expensive monitors in which each pixel has red, green, and blue instead of red, green, or blue).
For reference:
I hope this helps.
That makes sense. Thank you. I think the rules between additive and subtractive mixed together in my head and confused me.
One curious thing if you understand this is to think on purple. Purple is blue+red, but like you pointed out 2 colors should give you the average wavelength, which in the case of blue+,red should be green. So why the hell do we see purple as something different? Well, that’s because humans have 3 sensors for colors, roughly corresponding to Red, Green and Blue, triggering both Blue and Red without triggering green at the same time gets interpreted differently than green, even though it shouldn’t. Which means that purple is not a color, but rather a mind trick your brain plays on you.
I’ve been wondering - how do you make brown? Don’t really see it on the spectrum.
About 2 parts red to one part green.
Dark orange, it’s only brown when contrasted with something brighter.
There is a technology connection video that goes into more details.
red light + green light = yellow light
When you mix paint, you mix pigments that each absorb certain colors, so they won’t reflect it. You’re subtracting colors to the ambient white light that reflects a smaller and smaller portion of the spectrum on the painted surface, and if you mix enough colors you substract most of it and get a dark brown or even black. When you encode rgb values for a screen, you tell pixels to add colors to the light your screen is generating, and if you add enough you get a white light.
A piece of paper is white at first. After you’ve drawn colors on it, you’ve made it closer to black. If you draw in many different colors, it will eventually be black.
A screen is black (emits no light) at first. After you’ve made it emit light, you’ve made it closer to white. If you make it emit all colors at the same time, it is white.
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I think the difference is one is mixing light and one is mixing colour
I think this is not helpful, since both are “mixing colour”. I think a more apt analogy would be “shining multiple lights” vs “stacking colour filters”.
Have you played hexcodle
CMYK (Cyan, Magenta, Yellow, Key) is for pigments. RGB is for light.
Factoids.
There is a difference between colors you see from reflections, and from a direct source.
Your t-shirts is light hitting them, and reflecting back to your eye. Depending on what is reflected and what is absorbed, you will get a colour.
But that will not be the case from screens that emit their own light.
I think the simplest way to explain it is:
- colours in a computer work by adding light. Add enough light wavelengths makes white.
- colours in paint work by taking colours out of the light it is reflecting. Take enough light wavelengths out and you get black
