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Is it compulsory for good result to choose a zero value in either of any four c, m, y or k.

In CMYK, can't we select a colour which is not having any zero value?

I am designing infographics for both web and print but feel limitless in terms of colours because of this.

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    I do not understand your problem. You can choose any color you want. Just do not go beyond the total ink your paper can hold. – Rafael Aug 26 '15 at 11:40
  • Hi thanks for replying. Actually i was asking that is it necessary that in cmyk we should always have one value as zero? Eg :- – Designmate Aug 26 '15 at 12:01
  • I heard that cmyk should be only a three colour process for good printing. So that's why I was asking whether it's necessary to take zero as a value in any c, m, y or k. eg - If I want to take a brown color value as c-40, m-70, y-100, k-50, but there is no zero in any c, m, y or k. So should I choose this colour or not??? will it come good in printing??? Hope I am able to explain better this time? – Designmate Aug 26 '15 at 12:09
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No, you can use whatever values you want in CMYK, as long the total of the 4 values don't go above 300 ideally (for offset printing.)


I heard that cmyk should be only a three colour process for good printing. So that's why I was asking whether it's necessary to take zero as a value in any c, m, y or k. eg - If I want to take a brown color value as c-40, m-70, y-100, k-50, but there is no zero in any c, m, y or k. So should I choose this colour or not??? will it come good in printing??? Hope I am able to explain better this time?

Large area printed with 1 color

There's one reason why it's not a bad idea to use the 4 colors CMYK in SOME colors; it's to avoid the "stamping" effect on offset. It can happen when printer have to print large areas with the same color.

Example of "stamping" effect:

Stamping effect

But this is generally helpful when you use a 100% value for one primary CMYK color; by mixing 2 and more, you can get a better finish and it's easier to print for the press operator. It's a bit like applying coats of paint on a wall; when you use 1 color only and this color is very "thick", you will see the roll stamps on the wall and will need 2-3 more coats. On offset press, it's a bit the same principle; the other separations will act as the extra coats.

But the same issue can happen with 1-color Pantone printing and there's nothing you can do about it besides not using a 100% color on a large area; it's up to the printer to update his equipment to avoid this and it's also affected by the way they impose your artwork on their large sheets! It happens more often when the rolls on the press need to be changed and when there's big areas that are printed, and some white areas in-between.

Besides the rich blacks and light grays (or light M-Y-K or Pantone), you shouldn't force yourself to use values that will change your colors unless you want to.


Light gray or light 1 color separation

There's also very light density colors such as light grays that might look better if you enrich them a bit with the other CMY; this way it will hide the halftone pattern.

If you use only black (K) for a light gray, you might notice the little dots on the final printed sheet. The lighter your 1-color separation will be, the more distant and small the dots will be, and the more visible that effect will be as well! So that's one other situation when you should add a bit of the other color separations in your mix. The higher the LPI (print quality) of the offset press, the less it will be apparent.

This starts being more of an issue for density below 10% in 1 color only though. There's nothing you can do about it if you use a Pantone or 1 color print job besides using a good quality printer or having your densities above 10%. Or using digital printing!

Example:

Example halftone light density on offset

So that being said, you only need to be careful for light colors using 1 color separation or 1 pantone in general. And yes, in general, print operators don't like big mass of ink that uses only 1 color! I think that's what they hate the most actually, so if you can, you help them a bit by enriching your color IF it doesn't change your design.

It's usually very easy to calibrate a press when the colors have a nice rich density or bright colors, or a mix like the brown you described; anything skin tone, light tone, pastel, beige, sand is greatly influenced by a 1-2-3% change in the calibration and is more challenging to print on offset because a little extra in one of the other separation can change the final result dramatically!


Have a look at my answer thee, there's an explanation on "stamping" and also rich blacks:

What kind of black should I use when designing for CMYK print?


Source image offset gray: http://www.tkcups-sorgs.com/UI/Informations.aspx?i=gi

  • Hey thanks for your answer. A very gud point u told, that the total of the 4 values shd not go above 300 ideally (for offset printing.) I will take care of this. Thanks Again :-) – Designmate Aug 27 '15 at 8:12
  • I hav one more question. If u can answer pls? I am designing infographics on A4 size in illustrator for the client but presently I am sending the image sample in jpg in cmyk mode. My client require it for both computer presentation i.e in rgb and print also. But right now I am designing the infographic in cmyk mode. But wanted to know dat when I send the jpg sample to the client Should I convert it into rgb and then send??? And what is the proper method of creating infographic or any artwork in illustrator when the artwork is required for both web and rgb?as colour changes may b there is both? – Designmate Aug 27 '15 at 8:18
  • @user48947 You can use the "save for web" in the "file" menu for the web version, and choose the pixel size and quality there. The colors will automatically convert to RGB if you save this way and it will also give you an optimized JPG, perfect for web and with less kb. For the print version, you can save as PDF or export your JPG (but PDF has a better print quality.) There won't be much change in the colors from CMKY to RGB. – go-junta Aug 27 '15 at 8:36
  • Thanks... If we design something with any gradient background say light grey for eg. then will this gradient effect give a good result after printing??? – Designmate Aug 27 '15 at 11:11
  • @Designmate Yes, it gives better results with more separations than just black (K). But keep in mind that all light or extended gradients will be problematic because of the "stepping" effects due to each shade of that color. You can see the small example on the link in my answer under the title "Finally, it's better to use a rich black on gradients." You can always add some noise (2) and then a bit of gaussian blur (0.5) in your gradient to hide that stepping effect a bit. That kind of gradient should be done in Photoshop, not in vector. – go-junta Sep 18 '15 at 6:14
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This is a color theory issue.

In theory if you have lets say an orange (M50Y100) and if you add cyan you are neutralizing the saturation.

For example a neutral gray could be* a C50M50Y50 K0 or C0M0Y0K50. *(Thoose are not the exact values, I'm just posting that as an example)

But in practice if you reduce the 3 primary colors you reduce the posibility of a color shift in tone.

For example. If you add cyan you could shift a light orange to a greenish yelow if the print adds too much ink in the cyan channel.

You can see here you have the risk of passing thru the green part of the circle just adding cyan.

If you darken a color with just black you just make it darker, not greenish.

All that in the case the print house has little control on the process. If it has a decent quality this risks are reduced.

For example almost all spot colors are defined in a combination of all channels. Again this is asuming the press has good quality control.

  • Depicting it as a circle is a bit misleading as its actually a triangle. – joojaa Aug 26 '15 at 15:56
  • joojaa, are you trolling me? Xo) It is just a color wheel. The color space can be described as a circle, square, hexagon, cilinder, cube, cone, sphere... – Rafael Aug 26 '15 at 17:29
  • No the color space done by the printer is mathematically a triangle it is spanned out by three color vectors. – joojaa Aug 26 '15 at 17:40
  • Anyway, both of you can stop "trolling" or debating on this, I don't think that's what the OP wanted to know, unless I'm the one who didn't get the question right! heehee – go-junta Aug 26 '15 at 17:45
  • @go-me no the OP has a point theoretically you only need 2 colors and black to describe the color. Except its not really true the human eye in fact can metamerize different colors this way your monitor just cant show the difference. – joojaa Aug 26 '15 at 17:49

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