I know about how primery colours for light (addative) and for ink (subtractive) are different - the common knowledge states that they’re inversions of each other: Red green blue mix to for cyan magenta yellow… (like the circles bottom left)
But the cyan for ink is noticably different to the cyan for light!
(this is still true, but less so, with magenta, yellow, green, etc.)
Why is this?
What is the formula for converting RGB to CMYK?
Is this formula propriatry? (I noticew the gimp doesn’t have CMYK colour options)
One is an additive color-space, the other is subtractive. And, they are calculated for their intended uses.
If you intend to do “serious” color printing, hire a qualified print professional who will use special software to “pre-flight” your job for the particular papers and ink that have been chosen. He will show you, on a properly calibrated display, exactly what the final print will look like. Don’t try to “skimp” on this step. These people know what they are doing, and will guarantee their work.
“RGB to CMYK filters” are available, but do not trust your print-job to them.
You can see these three colors as linear independent vectors. ( in fact they are) Thats their main property. You can’t mix the third one as a combination of the other two. And together they span a threedimensional space of colors, but depending on how exaxtly you choose these three colors the resulting mixes for a final color will differ slightly and may also shift the size and shape of the final color gamut. So its a bit of the manufacturers tweaking.
CMYK is just there to get better and cheaper blacks than what you’d get by mixing it out of if the three primary colors themselves.
My understanding is that the two color spaces are designed differently because of their different purposes. The colors that you see on a printed page are what’s left after other colors have been subtracted by the ink from the white room light. The colors that you see on a video screen are pure and have been added to the otherwise-black screen.
You mean additive vs subtractive colormodels? Yes sure, they are totally different. Or better, they are the exact opposite. Mixing their primary colors equally in the one model produces white and in the other one black.
I was talking of cmy vs cmyk. (not rgb)
And why the pure cyan in the printer cartridge doesnt have to align with the pure cyan seen on screen.
A printer manufacturer will first and foremost be interested in a printer that delivers a good color range for its intended use.
A good color mapping ( also for the cyan itself ) from one colorspace to another is a different story, and rather just math and good calibration and mapping between them.
Yes they are. You are confusing things. The rgb and the cmy colorspace are exact opposites. So this is how you get it transformed into the other colorspace.
c = 1 - r
m = 1 - g
y = 1 - b
Another thing is the conversion from cmy to cmyk
where you take the minimum of cmy as k
and the new amounts of c m and y are calculated like this
c2 = (c - k)/(1 - k)
m2 = (m - k)/(1 - k)
y2 = (y - k)/(1 - k)
You can now combine these two to get your direct conversion from rgb to cmyk, thats up to you.
But thats how you’d calculate it as pure values stored as data.
To get a fitting result from your monitor to your printer you need simply spoken a mapping that compensates the specifics of all different devices used in the process. But that has nothing to do with the colorspace itself.
So if you are experiencing wrong colors your system your used combination isnt well calibrated. And what I wrote in my first post is one reason why such a calibration is needed.
Well , cyan in additive is 100% blue + 100% green, while cyan in painting is only a slightly warm blue.
I think it’s just two very different colors but with the same name, I don’t think there is more to look for…
And they also differ from indigo, indigo, indigo and indigo if you scroll the web search results further.
Color is a sensation, not a physical phenomenon. It happens in our mind, not the world around us. It’s the same as a feeling. An experience through our senses. Seems like bullshit philosophical statement, right? It apparently isn’t even when you look at it in the most technical ways and color science context. CMYK and RGB are different contexts. Same color can be the same and not the same at the same time depending on how you look at it.
It may be simply because that we call #00ffff cyan… or
and the “other one” original was made of:
???
Also:
Ink and paper
It depends on the quality of the ink and also the paper to print it on… for example simpe copy paper or highgloss…
There is also the seven (?) ink printing technology which does miz this even more…
Ahh… and then:
especially sub header → On the web and in printing:
While both the additive secondary and the subtractive primary are called cyan , they can be substantially different from one another. Cyan printing ink is typically more saturated than the RGB secondary cyan, depending on what RGB color space and ink are considered. That is, process cyan is usually outside the RGB gamut and there is no fixed conversion from CMYK primaries to RGB.
Using hex codes without specific context when speaking about color is one of the most notorious mistakes done by graphic designers all around proving they know nothing about digital colors. I thought you would know better…
Well… usually it’s “the name” of that color… cyan and i also especially linked the “side with other names” with slighlty different values (and all as HTML color codes/names).
And the original “contextual” color space… was not mentioned. So far about contex.
( also: Why should i blame any graphic designers or other experts for anything… they also just want to earn their living… )
Used a hex code without specifying color space. Shame on you.
That causes headaches for people working with them and for themselves. How many times have I seen a graphic designer working with their fancy Macbook with P3 color space monitor giving their clients working with Windows PCs and sRGB monitors unspecified hex codes…
What’s that about? I am not talking about any opinions here. It’s a real situation that happens all the time. Same hex code can mean different colors in different color spaces, that’s not an opinion, happens all the time. Sorry if my joke about shame sounded offensive.
I’m not going to pay any licence to be able to look up what cyan is in any patented color space like patone or something. I also think that any discusion about any color will not be any more precise if we use more than 8 bit per channel. Also giving some color space (like the mentioned site ->: HTML-colors ) will also not help because most users do not have a calibrated monitor (also for different environment lights… and so day times… etc. .)
And of course this can be going weird as this example … ( Telekom using Magenta… especially also the hex code… )
Any color is’ out the window’ as soon as it is viewed on anything other than the designers monitor.
Clients don’t tend to have fancy calibrated monitors, and print or video will look different on every device.
That’s why Pantone has a purpose to at least establish a base line for what it’s going to look like.
For video all bets are off, depending on monitor, color space and more.
Am I being a jerk in some way now? I don’t mean to. I mean we are just talking about color. It’s just a complex subject that can cause headaches when trying to understand. I thought I would bring up problems with hex codes, because OP seems to be sort of new to this whole rabbit hole. I though this problem is well known to you, Okidoki, and to joseph as well. There are countless threads on this forum about that, so I would never think this is something new or something controversial. It’s not an opinion, it’s how color management works. Color codes are just numbers, color spaces define what they mean. I don’t feel superior just because I know that - I thought most people here know the basic concepts.
Giving a hex code in P3 color space to someone working in sRGB without specifying is a mistake nevertheless since it’s most often assumed a hex code is sRGB like in the example of HTML codes - those are in sRGB. In most cases graphic designers do that without even knowing the difference or that they view colors in P3 color space though and that often happens to lead to a problem where colors differ - for example the designer sends something to print and the client sends something to reprint to the same company doing the printing. The designer uses his hex codes in P3, but converts to whatever color space required for printing, then the client uses the hex codes meant for P3 as sRGB and also converts to whatever color space required for printing and they receive the printed stuff and it differs visually when compared. And that’s a problem, nobody knows what’s going on and it costs time and money to figure it out. Am I the only one who have witnessed this happening quite a few times?
)