Setting up a printing machine for colour

[PeterArnel]

I am keeping on about this because it is now becoming a huge international issue. and why its important that u use the correct calibration. in Pacific areas
SWop colour and Colourbridge PC and Europe ISO Coated and Colour bridge EC WHY because what happens is that the Pantone CMYK split is adjusted for the different colour process inks between America and Europe (Japan also has its own)
The way we should set printing presses up is by comparing a grey made up of 50 Cyan 40 Magenta 40 Yellow and a grey made up of 50% black. They should be very similar. This means that when u make a neutral grey in Photoshop u get a neutral grey. It also means that we have virtually no lattitude in adjusting colour to impove images.All the adjustments must be done prior to us receiving the file.
Peter
I would welcome comments

[Ian Petersen]

I'm not sure what you want us to comment on. That printing inks are different in the US and Europe or that we should be using colour management? Or what sort of colour management should we be using and who should be doing it?

In my experience, trying to get a usable ICC profile from a commercial printer is akin to extracting the proverbial blood from a stone. "Oh, just send us the file we'll make sure it matches the print ... "

[PeterArnel]

Sorry for delay in coming back. The issue is that when designers convert to CMYK they must use a profile of some sorts. The default is the US SWOP. When European designers use the SWOP profile the CMYK mix of colours increases to allow for the weaker US magenta ink. when we in Europe print it with our inks - the images - the neutral greys come out pink- they should ISO Coeated profile for sheet fed litho.

[groucho]

<The way we should set printing presses up is by comparing a grey made up of 50 Cyan 40 Magenta 40 Yellow and a grey made up of 50% black.>

But why should a 50-40-40-0 mix, with 130% color in it, equal a 50% black? And why not 40-40-40-0, or some other blend? How do you arrive at 50-40-40-0?

I would expect that any "local" printer, using any color analyzer and a reference table for whatever inks they are using, could match any sample they were given. Including a sample from a swatch book, which is why Pantone make and sell those too.

Of course, a really enterprising printer could simply "run US colors" for US clients, then wash down and "Run EU colors" for EU clients, and so on. This shouldn't be a real issue for a printer doing their homework, should it? Don't ink companies have equivalent tables for their customers to use?

[PeterArnel]

But why should a 50-40-40-0 mix, with 130% color in it, equal a 50% black? And why not 40-40-40-0, or some other blend? How do you arrive at 50-40-40-0?
The question I think is more why not 50% 50% 50% of Cyan Magenta and Yellow. the only reason we use black is to give more tonal range and black type. in theory we shouldnt need any black in the pictures. 50/40/40 is an international standard which allows retouchers of images to know what % they need to make greys to get the right result.
Colour analyers ( Spectrophotometers) really only measure spot pantone colours. colours made out of CMYK mix cannot be individually altered on a printing machine

Pantone books vary in colour to much to be an accurate reference - the problem is they dont publish L a b colour references for their colours.

Changing inks could be a solution but not a pratical one - the main issue is that on one set of plates a designer could have images with SWOP calibrations and ISO calibration on.

The designer who is responsible for the artwork now has to take the responsibility (Thats what they are paid for)

Peter

[Ian Petersen]

European language versions (at least the Danish one) of Adobe apps default to Euroscale CMYK for conversions. English language versions default to SWOP. Britain is in the unfortunate position of speaking English but being in Europe. Although, if I'm not mistaken, the 'International' English version does default to Euroscale CMYK.

Assuming a PDF workflow, as a printer, would you prefer CMYK converted by the designer with a generic CMYK profile (Euroscale coated), CMYK converted with a specific profile for your paper and press, or RGB with embedded profiles so you can convert to CMYK yourself?

[PeterArnel]

Ian the new profile in Europe I understand is now ISO coated for offset. If you are a designer and retouching in Photoshop wanting neutral greys you must do the convertion your self to ISO Coated If you leave it to the printer - as we have just found out, our pre press that converts RGB to CMYK "Prinergy" installed by Heidelberg would convert to SWop colours.
THis is all coming to light in the UK as I speak
Peter

[Robin Springall]

We've just installed Adobe CS2 on our Mac and PC. When we choose Europe Prepress 2 colour settings the programs default to the ISO Coated FOGRA27 working space for CMYK, but we can select Euroscale Coated v2 instead - do you know how it differs from the ISO, Peter?

Our printer, "Hurricane" Catarina, sets the presses to Euroscale Coated v2 (so we're using that until and if she changes the spec).

[PeterArnel]

Robin
Did u get my email? it should always be ISO coated - and pantone library should be the colourbidge EC version which if u havent got u can download from the Pantone site ( or I have)
We have just set all our Epson proofers up to the ISO coated profile and when we printed 50 Pantone CMYK colour patches they got within 3 DElata E of the colour - more importantly when we printed it on our presses we got within the same tolerance. We are very close now to the holy grail of Standard proofing spec - matching press.

Peter

[Robin Springall]

Hello Peter, I think I got your email when I was in the middle of the busiest week in history, so not sure where yours went, I'm afraid, but I remember it looked frightfully technical <g>.

If Hurricane Catarina is using Euroscale Coated v2, surely I should use that instead of ISO, no?

Oh, and Delta E of 3? Bah, humbug! Call yourself a printer? I can see Delta E of 1.5, even 1.0 when it comes to some blues - yar boo sucks!

All the best, mate <ggg>

[Michael Rowley]

Robin:

Delta E of 3? Bah, humbug!

I seem to remember, delving into my now murky memory of thirty years ago, that a value of DeltaE < 5 was considered pretty good—nearly as good as an expert colour matcher could detect.

[PeterArnel]

Robin has 80- 80 vision I expect :-) the tolerances as u say are Delta E of 5 ( and that is harde to maintain on a Press

[PeterArnel]

Our printer, "Hurricane" Catarina hahaha - I dont know do I - I dont really understand how it joins up if it changes. All I know is that to achieve the new Pantaone colour bridge CMYK colours and to match images at the same time - we all have to work to ISO coated.
However ts early stages at the moment - we seem to have experts who only understand a small part of the work flow and cant join it up. Next week we are involving digital photographers to start at the beginning -I will let u know how it is going
Peter - man in charge of spectrophotometer
Seeing changes at DElata 1 - 2 is very good

[Robin Springall]

It's actually quite easy for the human eye to notice a Delta E of 1.5 with most solid blues, particularly on large fills. I've problems with this many times before, where a printer has said the run in within spec (dE 3) both both I and the clients can clearly see the mismatch in the colour. And a blue fill is one of the most common, of course :(

[Michael Rowley]

Robin:

It's actually quite easy for the human eye to notice a Delta E of 1.5 with most solid blues

Yes, it's easy with blue: I could see differences in shade on draw-downs very readily, even when the comparison was between 'identical' phthalocyanine blues from different manufacturers. Spectrophotometers weren't good enough then.

[Robin Springall]

And we find that blue is the most popular fill colour, damn it!