View Full Version : Photoshop RYB colour wheel?
10-07-2011, 11:34 AM
Any way in Photoshop to create an RYB colour wheel? I've come to the conclusion after two days of searching that everyone's RYB wheels on the internet are slightly different, e.g. everyone considers green to not be the same, and it certainly isn't anywhere close to 0, 255, 0. Is there some formula you can apply in Photoshop to mix yellow and blue together to get green, or is this simply not possible in Photoshop? I built myself an RGB colour wheel in Photoshop by dividing 360 by 12 which gets you 30, so you just move the hue slider 30 degrees and sample the colour at that point to build a 360 degrees wheel. Works great, what's the trick to making the RYB version of that same wheel?
I don't consider myself an expert on this topic, so feel free to disregard anything I say. But I think the RYB wheels are different because there isn't one single method to create green with RYB.
You could use CMYK but the problem with CMYK is that all the colors are different. I'd go for the one that's looks best to me if they're off by a lot. Naybe this isn't all that helpful =\
(and out of interest, why do you need a RYB wheel?)
10-07-2011, 12:00 PM
by definition 0,255,0 is green. If you want to mix two colours togtether to get a green you need to mix cyan and yellow. But it won't be 0,255,0 because you're not mixing paints or inks.
Do you mean a green colour that you would see if you mixed printing inks together? try making an image filled with 0,255,0 and then convert the image to CMYK. That will make the green a printable colour. Saving that try using one of the green colours from one of the printing ink sets. Like the Pantone swatches.
10-07-2011, 12:19 PM
Actually the whole point of this is so I have a quick reference chart for when I build colour palettes for worlds, mostly lighting. I like to know my complimentary colours in both paints and computers so I can make informed choices about what complimentary colours I choose. Of course I break these rules all the time based on what looks good in video games, but just the same I like to have a starting point. For example in the RYB model red's compliment is green, in the RGB model red's compliment is cyan. Went to that site kuler.com, there wheel is totally fucked as far as I can tell. It's the RYB wheel because it tells me the compliment of red is green, but changing the hue to 90 degrees does something really unexpected. It's a 360 wheel but 90 degrees is not a quarter of the wheel? Confused. Still not satisfied with any of this RYB bs yet, just doesn't seem to map to computer graphics.
10-07-2011, 12:53 PM
Well, this isn't a photoshop solution, but it's a website that does exactly what you're talking about. Maybe a screen grab could work? Or maybe just have an extra document of this, or another color wheel you make, open so you can just tab to it real quick and sample what you need to.
10-07-2011, 02:31 PM
How a hue rotation changes the wheel totally depends on how the color space rotation is achieved. Colors only go in circles inside the human head. So any hue rotation is a mathematical abstraction at best.
And no you can't mix yellow and blue to get green because yellow and blue don't make green. They make mush. This is why there is phthalo blue and ultramarine blue.
Paint mixing works because the pigments are not pure hues, so when you combine them, the wavelengths they both reflect are enhanced, while the wavelengths they do not have in common are muted. Try mixing a ultramarine with a lemon yellow to get a green. It will be something like baby puke green, or pea soup green.
When dealing with light, yellow is a secondary color. Its a wavelengths in between red and green.
Light is what computer graphics deals with, rather than pigments, as you've seen, pigment color mixing doesn't translate to light color mixing well. However, it does map nearly perfectly to human eyesight. We have chromareceptors cued to the primary wavelengths of light that we call red, green, and blue. They have a range of reception with some crossover of course, but their primary frequency response is to red, green and blue.
There are RGB reds that have greens as a complement. And there's nothign to say you can't skew the complement by a few degrees one way or another to make a more pleasing composition for the mood you're going for.
10-07-2011, 03:35 PM
you could try taking a screenshot of the linear colour picker and then using the "polar coordinates" filter on it.
10-07-2011, 06:21 PM
Stradigos, that site seems to map to 360 degrees correctly unlike that weirdo kuler.com site. Thanks for that link, it outputs hex values which I can use in Photoshop to build my own painter's wheel.
Vailias, my question is more what is the math difference behind Photoshop's RGB wheel vs http://colorschemedesigner.com/ wheel. There's some kind of conversion happening to make green the compliment of red and I'm wondering if there is some formula in Photoshop to get this result.
10-07-2011, 10:20 PM
Ah. Apologies for the over explain/mini-rant.
I'm not sure about formula, but if you find the equivalent photoshop RGB points you can see how its space differs. Colorspace is very much like regular 3d space and a rotation like this just needs a matrix to multiply the assorted colors through to get the new colors. So there is a matrix which will create the effect you're seeing, but in my experience matrix math isn't really something one does in their heads on the fly. :)
This particular colorspace is derived from a sort of "normal" RGB space that rotates around white, however its coordinates have been skewed. I don't remember quite enough matrix construction math to provide a sort of formulaic converter here right this minute, but yes its mathematically possible.
However, here's a sort of dirty version of the same conversion via illustrator and a distortion.
Basically there are more degrees of rotation in the skewed model between red and green than there are between green and blue. Its actually skewting the coordinate space making fewer possible cyan and magenta hues available, while adding many orange and chartreuse ones. The progression between colors in my little distorted circle there isn't exactly accurate to the wheel you linked, as it doesn't match the magenta range of the linked wheel.
The color offsets in degrees between cardinal 100% points on that wheel are (clockwise from top) 90 (yellow), 90 (green), 30 (cyan), 45 (blue), 60 (magenta), 45 (red)
A standard wheel would have 60 degree progressions between each point.
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