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I have a logo that was done with RGB colors, now I have to work with this logo to do something for printing purpuses, the problem is that in the RGB version of the logo I have a shade of green I cannot reproduce with CMYK... How do I do it?

I googled up a bit and found some CMYK values that would create a simmilar green, close enough, the problem is when I put those values in Illustratot(%C %M %Y %K) I don't get the color I am supposed to... what am I missing ?

I have an image to illustrate my problem :

do you see the difference?

The green I want to create in CMYK is the first green, when I put those values there I get the second green you see there, when I print this image will I get something close to the first green ? ...And this is simply how you view it on screen, a bit darked and washed up ? pom pomm pom pommmmmm

EDIT:

If I open up my logo in Photoshop and go to View > Gamut Warning the green part of my logo shows up in grey, to ged rid of the grey I lower the saturation, the problem is lowering the saturation ruins my nice bright neon green...

EDIT2:

If anyone around here printed neon green, how did you do it ?

I found on some forum someone saying that Pantone 802 C will print neon green, I looked it up, selected it and on screen it looks worse than my second green in the sample image... and anyway, putting a pantone color in a PDF that will be printed on a regular simple printer is any good ?

[The material the logo will be printed on will be downloaded by various users over the internet in PDF format and will be printed by various home normal hobby printers, so I will not have the control over that at all, I just want a green that will print neon/led green or something closer on a regular hobby printer, not in some fancy color lab/printer. Its imposible isn't it ?]

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    Pantone colors are specific inks, so, no, declaring a pantone color on a file that will be printed in CMYK is pointless. Alas, neon colors are simply outside the range of what CMYK can print. Best to come up with a different color scheme for the project.
    – DA01
    Commented Nov 10, 2011 at 16:04
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    One thing you need to realize is that ANY CMYK color you pick will not be displayed properly on an RGB device. You seem to be completely aware and unaware of this fact at the same time. The color authority is the output source, and for CMYK, that is going to be the printed item, or a suitable color-accurate proof from your print supplier. They simply CAN NOT be simulated accurately on your monitor.
    – horatio
    Commented Nov 11, 2011 at 17:48

4 Answers 4

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Short answer: you can't.

Technical answer:

RGB is additive. The more color (made of light) you add, the closer you get to white.

CMYK is subtractive. The more color (made of ink, which is reflective, which subtracts light) you add, the closer you get to black (or actually a muddy brown).

CMYK has a smaller range, or gamut, of colors it can reproduce than RGB does.

What you can do about it:

If you need that particular neon green to print, you'll need to find a spot neon color and specify that for your printer. That means the ink will be premixed to create that neon green, and will be laid on one plate, instead of mixing CMYK inks to achieve it. It will be a fifth color, and will cost extra.

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    @FlaviusFrantz If it's for common house printer, I suggest you do it with RGB.
    – Joonas
    Commented Nov 10, 2011 at 14:40
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    you can't replicate neon colors with CMYK, which is what nearly every home printer uses (there are some very high end 6-color printers). So, alas, you simply can't do what you are trying to do.
    – DA01
    Commented Nov 10, 2011 at 16:02
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    The answer is that there are no CMYK values which will reproduce your neon green on the HP printer bought at Staples sitting on your end-user's desk. Mourn the loss of the pretty color and pick another one.
    – Lauren-Clear-Monica-Ipsum
    Commented Nov 10, 2011 at 16:54
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    Is it true that CMYK has a smaller gamut? I was always taught that it had a different gamut, but it wasn't necessarily smaller. Here's a sample diagram pulled from google: jiscdigitalmedia.ac.uk/images/cie_gamut.jpg
    – DA01
    Commented Nov 10, 2011 at 23:57
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    Note that in-office printing is going to vary from printer to printer and also may vary depending upon the ICC profile settings on the individual computer, printer, and software package used to print the logo (word, photoshop, ie, and firefox might each produce a different result on the same printer on the same day)
    – horatio
    Commented Nov 11, 2011 at 17:51
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A couple of points adding to Lauren's and e100's excellent answers:

1) A desktop printer is an RGB device, not CMYK. Although the inks most such printers use are the standard four, sometimes with additional inks (my Canon proofing printer adds a "photo cyan" "photo magenta" red and green for a total of eight), both the printer and the software that drives it are designed to look like an RGB device to your application. That means you should NOT convert to CMYK before printing, to get the best results. You should make sure that you are using photographic quality paper, preferably one made by the same manufacturer as the printer, and that you pick the correct color management options. Those options are a whole subject on their own, so I won't try to cover them here, but the printer manufacturer's website probably has good information on that subject.

2) Neon (or "Day-Glo") colors are not like ordinary inks or pigments. They actually reflect more visible light than falls on them. The "neon" part is a fluorescent dye that absorbs incoming ultra-violet light and turns that energy into a visible color such as green, yellow or magenta which it then emits. That's why they have that glow. Needless to say, your desktop printer doesn't take inks with fluorescent dyes.

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    It's still a CMYK device (well, yours is CMYKXXXX), it's just wanting the image data in an RGB format.
    – DA01
    Commented Nov 10, 2011 at 23:01
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    @Flavius, you keep stating that "bright green close to neon" is what you need. I'm not sure how much clearer everyone can be when they say "you can't have that with a desktop printer". Sorry.
    – DA01
    Commented Nov 10, 2011 at 23:02
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    @DA01: As a practical matter, you have to consider it an RGB device. Even fairly cheap 4-color inkjets have a wider gamut than a 4-color offset press, and if you send CMYK data (limited gamut) to a desktop printer, it's going to be converted back into a (now limited) RGB anyway for the printer to work with. It's counter-intuitive, because hey, there are 4 inks and they're C, M, Y and K, but if you treat them as CMYK devices you're working against the technology rather than with it.
    – Alan Gilbertson
    Commented Nov 10, 2011 at 23:41
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    Consider the nit successfully picked. :-)
    – Alan Gilbertson
    Commented Nov 10, 2011 at 23:55
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    Definitely. Using a dark background will make the green appear brighter (but your ink jet users might not like that ;). A glossy paper will also help make the colors seem brighter.
    – DA01
    Commented Nov 11, 2011 at 5:25
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You state the problem correctly: "in the RGB version of the logo I have a shade of green I cannot reproduce with CMYK".

But you are not using the most saturated CMYK green you can: c63 m0 y96 k1 clearly has a small amount of black in it, and isn't fully saturated on any channel.

Start with c63 m0 y100 k0 and try different values of cyan.

If you were getting this printed on a press, I'd advise you get hold of a CMYK sample book to see how it'd print.

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  • what is a process sample ?
    – Flavius Frantz
    Commented Nov 10, 2011 at 14:01
  • Process colors = CMYK. A process sample is usually a color wheel of sorts printed by the printer for a true comparison of what the ink will look like when printed. Pantone also produces and sells lines of CMYK color books that can be used.
    – DA01
    Commented Nov 10, 2011 at 16:28
  • But not relevant for home printers. I've amended my answer.
    – e100
    Commented Nov 10, 2011 at 16:47
  • True! Good point. Unless Pantone now sells 'guide to the world of ink jet printers' books (which I wouldn't put past them to sell...as they seem to want a monopoly on the color market ;)
    – DA01
    Commented Nov 10, 2011 at 16:54
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You CAN print neon colors! It has to be a custom multi-layered screen print job for every individual color with a custom ink with fluorescent pigments in it. Beware they look very different in normal light compared to that of low-light, special UV light, blue temperature white light, etc., You can even add a transparent layer of this over whatever pigment you're using as well.

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    But that wouldn't be CMYK printing
    – Cai
    Commented Apr 19, 2017 at 23:18
  • converting RGB to CMYK will have gamut losses. This is work around if that is really needed. you can print RGB itself with screen printing with RGL printing that is very close to RGB.
    – Nav
    Commented May 1, 2017 at 14:16

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