RGB(0,0,255) in CMYK

[brentjschaan]

I create an RGB/8 document and make a square that is RGB(0,0,255).  That's the exact colour I want to see.

How do I make the EXACT same colour in CMYK??????????  I use all kinds of online tools where you put in RGB and it spits out CMYK and put those values in and never comes out like I want.  The should not be difficult.  Someone show me simple, step by step please.  I've read all the stuff about why it's different blah, blah, blah.  Yea.  Just help me fix it please.

[Joachim_L]

Welcome to the Affinity forums @brentjschaan

Sorry. Seriously? Do you read all the blahblah why it is different? You understood it? It is not difficult, it is simply impossible. Except someone invented a new printing technology and I did not notice.

We can only get approximately there. Or closer with a spot colour, but not with CMYK. Sorry.

[Alfred]

Welcome to the Serif Affinity Forums, @brentjschaan.

48 minutes ago, brentjschaan said:

I've read all the stuff about why it's different blah, blah, blah.

In that case, you should know that RGB is an additive colour model but CMYK is subtractive. RGB(0,0,255) is achieved by the emission of pure blue light (i.e. no red or green component) and the nearest you can get with CMYK is a combination of cyan and magenta (where those colours are reflected and the other components are absorbed). The gamut (or range of colours) for the CMYK colour space is much smaller than the gamut for RGB, so there are some colours — notably the brighter ones — for which you’ll never get a close match.

[v_kyr]

[Fixx]

So you want brightest blue possible? In RGB display it is made with single blue component. CMYK does not offer single component for blue, so it must be made mixing two colours – cyan and red. As you may notice, mix of two components is never as bright as single one, not to mention that the more you add colour in subtractive system the darker the colour gets.

All replies written above apply.

[brentjschaan]

How then does versaworks take my RBG image and make it come out the exact same way on the printer.  That indicates it is possible at some level in some way.

[v_kyr]

34 minutes ago, brentjschaan said:

How then does versaworks take my RBG image and make it come out the exact same way on the printer.

Well that's a vendor specific RIP-software which is optimized for their own large-format inkjet Roland printers. So it's by far no mass market software solution for arbitrary home printers or the like.