Dan Margulis Applied Color Theory

Why Do Printers Convert Files?

   Date: Wed, 30 Mar 2005 20:16:26 -0800
   From: Steve Peters
Subject: Why are my files being converted?

I am a retoucher in San Francisco. I handed off my CMYK file to my client. I converted it using the U.S. Web Coated (SWOP)v2, and attached the profile. I was asked to prepare the file for web printing on coated stock. This is going to run in several different pubs.  They then gave that file to there separators. He then converted that file to there matchprint profile.  They then called me and had a few more changes, and wanted me to work on the file that separators had proofed. My question is this. If the separator does not have a profile for the specific pub, then why would he need to convert my file? I am assuming that it is only to make sure that they know what they will be getting from there proofer, but the end result is not going to be any closer than what I am able to give them from my Epson 4000 with the colorburst rip, correct? It seems to me that this is one big waist of time, is it not? This Epson is SWOP certified, so couldn't they use this instead of the match print? The only difference is that there is no dot, correct?
Thanks,
Steve
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   Date: Thu, 31 Mar 2005 08:05:40 -0500
   From: Jim Rich
Subject: Re: Why are my files being converted?

Steve,

If this company does a conversion to their matchprint profile, they then do have a target they are shooting at.It sounds like you want to shoot for that same target or have them  shoot at your output target.

As for having a rip that is SWOP certified, one could ask this question: What flavor of SWOP and for what press? SWOP is a guide line and not a standard.   So your proof out of the box will be different than a Matchprint.

One  reason is because the CMYK target you  have asked for in the rip is not your clients Matchprint target. You might be using the CSE CMYK or something like U.S. Web Coated (SWOP)v2.

So  if you want to get the CB rip closer to your clients target of a Matchprint, get their Matchprint profile. Place the Matchprint profile into the Input  CMYK part of the CB rip (the Source CMYK). Use Relative Colorimetric. If you have a good Epson printer profile you should  get a proof that is very close to their Matchprint using your SWOP certified Epson and  CB rip.

Jim Rich
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   Date: Thu, 31 Mar 2005 13:26:41 -0000
   From: Stephen Marsh
Subject: Re: Why are my files being converted?

Steve Peters writes:

I am a retoucher in San Francisco. I handed off my CMYK file to my
client. I converted it using the U.S. Web Coated (SWOP)v2, and attached
the profile. I was asked to prepare the file for web printing on coated
stock. This is going to run in several different pubs.  

All sounds 'good' so far.

They then gave
that file to there separators.

The file was originally separated by you.

Do you mean their prepress department?

He then converted that file to there
matchprint profile.  

So perhaps separators is the better term, or perhaps re-separators!

Well, there are two camps here Steve, and it sounds like you agree with me and expect the first option.

A) If you hand off CMYK, then that is the actual colour numbers that you wish to be honoured. This is the legacy, traditional way of things.

B) If you hand off CMYK, it may or may not be honoured and  it may be converted as they know their press better than you. But they need to know what profile you 'separated' with, if they have untagged CMYK then they are creating the colour with the profile that they assign rather than just sending the original numbers to output as in option A above.

If what you describe is correct, then they should have simply output the CMYK numbers in your file and sent them to a softproof or even a hardproof (digi or analogue). You do not wish anyone to alter the CMYK mix of your job, you wish to see how that CMYK mix is expected to print in their conditions - a conversion ruins this test!

If their press is close to the TR001 response that you separated to, then you will get the colour you expect. If it is not, then you may get a different composite colour appearance than you intended - but at least you will have your CMYK values honoured and not messed with.

They then called me and had a few more changes, and
wanted me to work on the file that separators had proofed.

Where if they had just proofed your ORIGINAL CMYK VALUES without changing them, you could have done the changes at your end without needing their file.

If they send you their matchprint profile, then you could convert your CMYK to their CMYK, just like their guy did, then make the changes that they wish...or have they done more edits than just a profile conversion from your data?

My question is this. If the separator does not have a profile for the specific pub,
then why would he need to convert my file?

They should not convert, even more so in a traditional film proofing process.

They should output your CMYK file without changing it, ignoring the profile and just sending it to print. If you have a green colour in the file made of 90y60c - that is what you expect to get on the film and have that proofed.

For digi proofing, a 'copy' of the data that will be output to film or plate is converted from CMYK to the inkjet CcMmYK or whatever space is in use, but this converted data is never output to film, it is only for proofing and your original data is output as you expect.

So what do you mean by 'matchprint'.

Is this a digital Matchprint or a traditional film and chemical proof?
 
Stephen Marsh.
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   Date: Thu, 31 Mar 2005 10:01:58 -0800
   From: Steve Peters
Subject: Re: Why are my files being converted?

I guess what I am really wondering is, do they really even need a "matchprint"? Aren't most magazines direct to plate these days? It just seems silly that they need to convert my file to there proofing system. I asked the guy at the separators, if the profile they use to convert my file was just for their matchprint, and he said yes. These guys are not printing these files. They are just preparing them for print. Dropping in the copy, logos, etc. So I really do not think that they have any better a profile, when it comes down to the final print than I do. They are really in the same boat I am. I have not found a magazine that actually has a profile for their press conditions. What they usually tell you are the generals, like "prepare files for to SWOP standards for coated stock, 133lpi, etc". That's it.

How often is film run these days? That is really the only time when having a "matchprint" is going to get you any closer that what I can get on the Epson 4000 Pro?

Steve
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   Date: Thu, 31 Mar 2005 13:19:30 -0600
   From: Mike DeSantis
Subject: Re: Why are my files being converted?

I've been lurking in the 3/4 tones and had to respond to the need for a Matchprint or equivalent print. It's for the client as much as it's for anyone. The people who generally pay the bills in the end don't care how we get the right color, they just want the right color. If the printer, the artist and the client all sign off on the final proof, and it doesn't come pretty darn close to what rolls off the presses, the client will turn red, with or without profiles, color spaces and densitometers. By all means, let's get better at the small part we play in publishing, but let's remember who our patrons are…

Mike DeSantis
DeSantis Photography

www.desantisphotography.com
573-875-5511 / voice
573-639-MIKE (6453) / cell
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   Date: Thu, 31 Mar 2005 11:48:57 -0800
   From: Steve Peters
Subject: Re: Re: Why are my files being converted?

Stephen,
On the back of the proof, it says "Kodak Polychrome, Matchprint, digital halftone". So, I am guessing this is a digital proof. I have never worked at a prepress place. I started out as traditional illustrator, but have been doing retouching for the last 10 years. So all I know is what I have learned, and from the few people I have talked to at prepress places.

In the previous post, Jim had said that I should convert my files to there profile. What I am trying to figure out, is, is this really the best thing for my client, the art directors and production managers at the ad agency?
Steve Peters

Steve Peters
Main: 415.285.4221
Direct: 415.999.2725
www.stevepetersdigital.com
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   Date: Fri, 01 Apr 2005 00:30:58 -0000
   From: Stephen Marsh
Subject: Re: Why are my files being converted?

Stephen,
On the back of the proof, it says "Kodak Polychrome, Matchprint, digital
halftone". So, I am guessing this is a digital proof. I have never
worked at a prepress place. <<

I can't comment on this proofing method and system etc.

Generally speaking of inkjet proofing, they would have sent a copy of your original CMYK data – with no conversion to this digital proofer.

The RIP at the proofer would do a `soft conversion behind the scenes' – it would assign a CMYK profile to the incoming CMYK colour numbers and then convert to the CcMmYK or CMYK or whatever is in use on this digital device.

The profile assigned to the CMYK numbers would have to be similar to TR001 in order for your colour not to be substantially altered from your original intent.

In the previous post, Jim had said that I should convert my files
to there profile. What
I am trying to figure out, is, is this really the best thing for my
client, the art directors
and production managers at the ad agency?

Well if their profile does a better job of describing the final conditions, then yes. And if it uses a different GCR ratio that suits the image content better than the middle of the road Adobe v2 profile, then yes.

The v2 SWOP profile from Adobe is quite good, but I am not a fan of the heavier than traditional black generation used in these various CMYK v2 profiles.

Chromix did freely offer a range of TR001 CMYK profiles using light K and Medium K GCR and also UCR at 280, 300 and 330 ink limits. The thing that I don't like these profiles is that they have a `contrast curve' in the perception transform which alters the look of the conversion from the RGB too much for my liking, but it is often stated that this is `needed' by those who make profiles. Not sure on that, but Adobe do not do this and I agree with them, if not on the black generation issue.

Stephen Marsh.
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   Date: Fri, 1 Apr 2005 09:14:26 -0500
   From: Terry Wyse
Subject: Re: Re: Why are my files being converted?

On Mar 31, 2005, at 2:48 PM, Steve Peters wrote:

On the back of the proof, it says "Kodak Polychrome, Matchprint, digital
halftone". So, I am guessing this is a digital proof. I have never
worked at a prepress place. I started out as traditional illustrator,
but have been doing retouching for the last 10 years. So all I know is
what I have learned, and from the few people I have talked to at
prepress places.

This is most likely either a Kodak Approval or Creo Spectrum halftone dot proof and NOT an inkjet proof. Either of these devices can use the Matchprint Digital Halftone Proofing material. You should know that there are different types of material/"inks" they could be using. KPG (Kodak Polychrome Graphics) offers different materials that vary in density and chroma/hue characteristics depending on the type of printing the individual shop is doing. The primary difference would be between a "SWOP"/Publication proof or towards more of a GRACoL/Commercial proof. And from this starting point of basic process "ink" sets, the proofs can all be calibrated differently and "tuned" the the individual shops needs for dot gain/tone reproduction. The POINT is that just because there is a certain watermark or whatever on the back of two proofs does not necessarily mean the two proofs will match. Even if they say it's a "SWOP" proof, this can mean different things; is it simply calibrated to SWOP densities but the dot gain is tuned to match their presses? is it calibrated to SWOP density AND dot gain? or has the system been calibrated in accordance with the Application Data Sheet posted on the swop.org web site for that particular device? These are important things to ask.

In the previous post, Jim had said that I should convert my files to
there profile. What I am trying to figure out, is, is this really the
best thing for my client, the art directors and production managers at
the ad agency?

If the best thing for your client is to get back a proof that meets their expectations in terms of color and how it will print at particular print shop then, yes, why not get a profile from their press or proofing system and convert directly to that? If it's an individual image and you want to hedge your bets, send them one converted to USWebCoatedSWOP and one using their custom profile. Send them the images untagged and have them proof both (obviously be sure to name them so you know which is whcih when you get the proofs back). Assess the difference and decide for yourself whether it needs the custom conversion or whether the generic SWOP conversion is close enough. If it was me, I would throw in a 3rd conversion using the USSheetfedCoated profile. Since this is (supposedly) made from an analog Matchprint, it MAY more closely match the characteristics of their proofing system.

Cheers,
Terry
_____________________________
WyseConsul
Color Management Consulting
704.843.0858
http://www.colormanagementgroup.com
http://www.wyseconsul.com (coming soon)
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   Date: Mon, 04 Apr 2005 15:47:40 -0700
   From: Steve Peters
Subject: Re: Re: Why are my files being converted?

So let's assume that I now have the same CMYK profiles that the shop in question has. If I use those, then print from my Epson 4000, will I be able to get a proof, that in the end would be as good as what they will get from there prooifng device? Knowing that these are going to be printed in many different pubs, and that they do not have any profiles for all of those different presses, there is no way that they are going to be able to get a perfect match anymore than I am? What I want to be able to know is this. Can I tell my client, the production manager at the agency, that there really is no need to get a matchprint, creo, kodak approval, etc. That thay can just use my proof from my Epson 4000 (with the colorburst rip)?

Thanks guys for all of your help,
Steve
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   Date: Tue, 5 Apr 2005 09:27:03 -0700
   From: mac townsend
Subject: Re: Re: Why are my files being converted?

On Apr 4, 2005, at 3:47 PM, Steve Peters wrote:

an I tell my client, the production manager at
the agency, that there really is no need to get a matchprint, creo,
kodak approval, etc.

IMHO, If you want to be responsible for the printer's work, sure, go ahead.

If not, no.

Mac Townsend
Adcom Graphics Digital Imaging
Fairfield, California
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   Date: Wed, 06 Apr 2005 01:33:29 -0000
   From: "kmlathan2003"
Subject: Re: Re: Why are my files being converted?

I hope I have followed this thread correctly, but here goes. We have inkjets and digital proofing devices. Our inkjets have printing folders with parameters set to 'match' our digital proof which the printers we deal with can match. So, if you have done testing that can demonstrate that your inkjet can 'match' the output of a digital proofing device and that the printer will also accept your proof as a contract proof, than go for it. But in my opinion, everyone down the line needs to come to that agreement. Just understand that tests need to be run. Also, how are you going to demonstrate that your device stays within tolerance between proof to proof? Are you willing to accept the final responsibility for the proof you provide? Are you printing on paper with inks that do not shift significantly with changes in environmental conditions? You might want to consider that if the printer will not take your inkjet as a proof to match to, than maybe all rounds of color until you get to final signoff can be done on inkjet, but a digital contract proof will be the final signoff as long as everyone between you, the agency and the premedia company pulling the final contract proof can come to agreement on the color 'match'.

Always include the appropriate color bars on your proof as well. A printer or premedia company can tell you what is best to place for their needs.

Best,
Kim Lathan
Color/Digital Proofing Manager
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   Date: Wed, 06 Apr 2005 12:22:18 -0700
   From: Steve Peters
Subject: Re: Re: Re: Why are my files being converted?

Thanks for your response. The Epson 4000 Pro is SWOP certified, so that means that all printers should except this as a contract proof, correct? The rip that comes with the Epson 4000 pro does do linerization. As far as I know the Epsons inks are very stable, maybe someone with more knowledge to comment on this.

What I am trying to figure out, and I have asked this before, is this. Since I never really work with the printers directly, and since all of my work runs in many different pubs, I never really know the press conditions, or ever get a profile. I may be told that I need to make sure that my files will meet the SWOP standard for uncoated or coated stock, or maybe that it will be printed on a sheetfed press. Even when I have contacted the publications, all I will be given is what I stated above. I am pretty sure that the guy who converted my file, is also going on the same info I am. So what does this mean. They obviously have spent time getting their proofing divice to some standard, I would assume that this would be SWOP for web, and GRACoL for sheetfed. I know that the SWOP standard is very broad, but it has to be closer than no standard at all? This is the main reason for me buying the Epson 4000 Pro, the fact that it is SWOP certified. Now Bruce Fraser does not believe that you can really get an better results using a RIP, as far as color accuracy is concerned, that you can just doing a cross render in photoshop. I think I agree with him, but the SWOP certification has to mean something? I should mean that this combination of printer, inks, and paper are going to be reproducible in CMYK, correct?

Thanks,
Steve
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   Date: Wed, 6 Apr 2005 16:38:12 -0700
   From: Jono Moore
Subject: Re: Re: Re: Why are my files being converted?

I think the chances of a printer accepting an inkjet proof as a contract proof are pretty slim unless you have worked with the printer before and they know that they can rely on the it as being accurate.

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