Say I work in CMYK, embed the profile in the PDF and send off to the printers. Say it has a TIC of 330%...
Hopefully, the printer will use my profile to print.Do they ever do that?
They 'strip' my profile and use their own, say a 'similar' 330% TIC profile.Everything should be okay, then?
They 'strip' my profile and use a profile with say 300% TIC.Does that put too much ink on the print?
They 'strip' my profile and use a profile with say 400% TIC.Now my blacks print lighter?
They don't 'strip' my profile and use their own profile on top of it.Is that possible?
If the profile is 'stripped' from my PDF, what does that mean in fact? Especially in terms of the TIC?
Ok here is how it's supposed to work and it does for the most part but for some unknown reason some people open your PDF in Illustrator or InDesign and output from there. Then all bets are off, the concept is as foolish as drilling holes in the bottom of your fishing boat!.
With that said in a proper postscript/PDF work flow the printer establishes an ink limit linearization dot gain curve for their work flow (press). it is not an ICC profile but it does have a TIC. Your file is imported to into their prepress workflow and when your file is processed it ignores the ICC profiles HOWEVER it uses the CMYK numbers which were established in your file by the ICC profile and when you created the file.
Remember an ICC profile has ZERO effect on CMYK color unless its being converted from another color space or model. Then it established the gray balance curves and the TIC. Vectors or raster objects created directly in CMYK are unaffected by the profile and the CMYK numbers in the file just pass along.
So if the press linearization dot gain curve has a TIC of 310 and if your images were converted from RGB to CMYK with an ICC profile with a TIC of 330 and contents of your file were created with content exceeding the TIC of 310 then the process will compress the dynamic range of your color to fit.
Ergo you will lose 5 points per channel in theory 20 points total. In reality it does this compression in a perceptual manner and unless you really know what you're looking for you'll miss it.
People with 45 years of experience like me actually plan for this to make images ( in laymen terms) pop on press, increasing the perception of contrast but it's only an illusion.
I’m going to read through that a few times to absorb it all. It is a great help having thorough explanations as to how things work. Usually, when I don’t really know what I’m doing, something goes wrong! I really want to establish a workflow that’s as reliable as it can be.
Unfortunately you need to ask your print venders how they handle your file. If they use Illustrator or InDesign, in fact anything other than their dedicated prepress PDF plugins to open your file I suggest that you find another vender.
99.9% of quality print shops for the last 25 or more years use RIP software that is EPS based, for the last 15 years it is PDF based digital front end postscript output and for the last 7 or 8 years it's a true PDF based RIPS.
That translates into EPS (assumed color space support), no transparency support, PDF digital front end, postscript output true color management support, limited transparency support, True PDF RIP has color management support and live transparency support.
I've just recently hooked up with a print company that looks very promising. The guy on the phone is very knowledgeable and helpful. They're sending me cromalin and digital proofs for a variety of jobs I have in the works. So now I know some of the questions to ask!
And I want to establish a good RGB/CMYK workflow, but from research and conversations with various people, these are the solutions I have come across...
'Work in RGB and let the press people do the conversion to CMYK. Modern presses do it better than you ever could with your software package.'
'Work in RGB, soft-proofing in the CMYK profile that the press uses. Export your PDF as CMYK, embedding that profile. The PDF export does the conversion.'
'Work in CMYK using the profile that the press uses. Convert your images to CMYK as you work in your document. Export your PDF using Native color space.'
I'm sure there are other approaches. For example, what if an eBook is to be produced as well as going to print?
Maybe the answer depends on the print shop and how they work?
Seamus Byrne said:Maybe the answer depends on the print shop and how they work?
Seamus Byrne said:Work in RGB and let the press people do the conversion to CMYK. Modern presses do it better than you ever could with your software package.'
Yes and no! If the work is going to an inkjet or a RIP driven digital print engine YES work RGB and let the conversion take place in the RIP because the CMYK gamut of these devices is wider than normal CMYK gamuts. No if you're going to a traditional print press, the RGB to CMYK conversions in most cases will be worse in a press RIP.
Seamus Byrne said:'Work in RGB, soft-proofing in the CMYK profile that the press uses. Export your PDF as CMYK, embedding that profile. The PDF export does the conversion.'
No. If you're going to press work in CMYK, choose a CMYK profile based only on the TIC that's as close to the printers recommended CMYK profile as possible and the gray balance that appeals to you. Soft proof the CMYK profile you choose.
Export PDF as native color unless required to use a PDFX export if required. The latter is all BS but you can't train some monkeys. Make sure you flatten all transparency.
"TIP" to check TIC on a CMYK profile create a vector fill with R0 G0 B0, then check to see what the CMYK numbers would be in the fill dialog, add them up that's the TIC of the CMYK profile you've set CorelDRAW to.
Seamus Byrne said:'Work in CMYK using the profile that the press uses. Convert your images to CMYK as you work in your document. Export your PDF using Native color space.'
For print press work, Yes for 99.9999% of all jobs unless you get some monkey that demands a PDFX of some type. Make sure you flatten all transparency.