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I have been looking for maximum possible colors in CMYK over internet, but all I Got it was RGB possible color 256^3.

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  • Watch an old offset litho press running up the first 100 sheets to know the answer is "infinite".
    – Tetsujin
    Jul 27, 2020 at 7:13
  • Your estimate for RGB is only because you assume 256 values per channel -- an artificial constraint. The model does not care about byte values. Proof: there is such a thing as "16-bit RGB", with a much larger range.
    – Jongware
    Jul 27, 2020 at 8:05
  • Are you asking how many colors can be specified in CMYK (theoretical colors, we could call them) or how many can be physically rendered as distinguishable colors? For that, there's no way to answer w/o knowing the entire output process, start to finish, the output medium and the color perspicacity of the person doing the evaluating. Jul 27, 2020 at 17:15

3 Answers 3

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That is entirely dependent on the device doing the output of your CMYK color. Just like the monitor affects how many colors it can display (many highend monitors can display 1024^3 color combinations some more, but many cheapo monitors can only reach 128^3, professional digital cameras typically store 4096^3)

So its not correct to say rgb can do a maximum of 256^3 colors. 8-bits per pixel color can make that many unique color combinations, but many editors can work in 16 bits per channel (for 65536^3) or even 32 bit float is common in vfx (2^64^3).

Now how many colors can a printer make? Well that is eiter a stupidifyingly simple question or a horribly complicated one.

If its a laser, press... But not a inkjet then the easy answer is:

  • A 4 color printer can make 4 colors.

The hard answer is:

  • A 4 color printer can make 4 colors but it can mix an area with diferent colors a but like dithering on computer displays so how many colors it can display is dependent on the size of the raster screen. The raster screen is technically user configurable so you can adjust how many colors mixtures it can make.

On a inkjet and other exotic devises thigs are different.

How many cmyk colors can the RGB display show? Well that also depends on what device your emulating. But less than it can show rgb values.

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  • Since the OP is trying to draw a comparison (flawed as it may be) to the 8-bit RGB's 256^3 possible color values, would it make sense to say CMYK's equivalent would be 100^3 but the average process is capable of reproducing significantly less? And what would that figure be? According to this source it can produce over 16,000 different color combinations but I can't seem to find any more references to back this up.
    – dev
    Nov 24, 2020 at 13:04
  • @dev it has no set value, I the operator/designer/user can adjust this as much as i want. I can get more intermediate colors or less its just depends on how i make the artwork and/or what kind of RIP engine i have. The reason you can not find a definitive answer is simply that there isnt one. The question makes little sense, even. I dont need to have same setting for the whole page.
    – joojaa
    Nov 24, 2020 at 13:10
  • Can you share an example on how a designer might adjust it as much as they want? A mathematician would tell you that picking a number from 0 to 100 over 4 channels would give you a total number of exactly 101^4 possible combinations (if we treat K as a primary) so surely there has to be a (non-infinite) upper bound.
    – dev
    Nov 24, 2020 at 14:46
  • @dev its a question of how big raster you chose. A print does not operate on a pixel a individual dot only has 10-12 possible variations. But a dot is small smaller than a pixel so you consider multiple dots as one element since they are not individually visible. This group is called a raster. now how many conbinations you can get is only bounded by the size of your raster. Since you can make a binary image manually that has exact device dots and make a arbitrarily large raster. Typically this raster is ten by ten or twelve by twelve but it can be larger. Also known as LPI
    – joojaa
    Nov 24, 2020 at 16:31
  • Also on a inkjet you can vary dot size, and usually have 8-10 inks... So it really depends on a lot of factors. I mean our sublimation printer when transfered on aluminium looks like a hight end tablet quality in well lit conditions. Bith in color range and levels.
    – joojaa
    Nov 24, 2020 at 16:36
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104 060 401 (101C x 101M x 101Y x 101K) colours are theoretically possible if you consider every channel in a CMYK file can have one of 101 values (1 - 100 colour values + 1 zero colour value).

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    This is an oversimplification, because in modern print systems you actually use an 8-bit scale per channel, so you can have 256 per channel. But yes, it is one way to answer, although you normally do not print 400% ink, you have dot gain, etc.
    – Rafael
    Apr 26 at 18:16
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While you can try to calculate an amount of distinctive colors in CMYK, it wouldn't make much sense.

In RGB colors are mixed in an additive color mix, which means every RGB value results in a unique color value. In 8-bit Black is R=0, G=0, B=0. All colors together add up to white (R=255, G=255, B=255).

CMYK colors work very differently, in a model called subtractive color. In theory Cyan, Magenta and Yellow add up to black, which in reality would give something dark brownish. So Black (aka K) is added as helper, also to reduce buildup of color that would smear and also take too long to dry. CMYK colors are intended for a printing process with translucent inks like in offset printing or inkjet/giclée. Software like Photoshop tries to simulate the CMYK output on a computer screen (which itself works in additive color mode), but there are many other factors (like the paper) that will have an impact on the result.

CMYK is very limited compared to RBG and the difference is not easily explained by values like number of possible colors. Some colors work very well in CMYK, some won't - which is due to the fact that lighter colors are achieved through a screen grid, so lighter colors basically loose their brilliance. Some inkjet printers use light-cyan and light-magenta to compensate for this.

On a computer screen every color that has a K-value of 100% would be black. In a printing process you could achieve different rich blacks by combining black with the other colours, so the actual color range also depends on the output medium.

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