Question for PrePress folks

[ecm28]

Lets say a customer sends a pdf file all in RGB. What is the best method (other than creating the original doc/scans in cmyk before the pdf)for converting the entire pdf in one shot to cmyk without a major color change. I know each company has different rip/ctp systems for handling files. I am curious if the rip systems you use covert your postscripts to cmyk or what everyone likes to do. I am just looking for a nice smooth method for converting the documents without having to explain to the customer that it is not correct, there will be a major color shift depending etc.

Thanks

 

[jimoblak]

Maybe the customer intended RGB images in the PDF file. Maybe those RGB images have color profiles assigned.

Aren't you offering a proof?

 

[ecm28]

Sorry for the confusion, This is not regarding a specific job or for proofing purposes. My question is for converting rgb files to cmyk for printing needs and a nice efficient way to do so without a drastic color change.

Thanks

 

[jmgalvin]

A lot depends on what's in the pdf, photos, text, etc. But it's not the job of prepress to change rgb to cmyk. The designer is supposed to supply cmyk.

We receive a tremendous number of photos for inclusion in various materials or for prep for magazine/newpaper publishing. Virtually all come in rgb jpeg format. Simply changing the mode from rgb to cmyk in Photoshop rarely produces any negative effects. If they came in pdf there would be no change to this.

In most other cases- text, logos, etc - you should not have that great a problem. After all, every rgb color has an equivalent cmyk. 100% cyan = r0, g172, b236 etc. When you're looking at stuff on your monitor you're seeing rgb. Pantone recommends bringing in the image and using the eydropper to pick up a color, add it to the swatch palette, and then changing that swatch to cmyk. That's ok unless you have a lot of different colors.

If you're talking spot colors vs process, now you're going to run into problems. That's where the real shift will occur - dependent on the particular color. If spots are picked up in great quantity, the person sending the pdf should be notified.









Using OSX 10.3.9 on a G4

 

[ecm28]

Lets look at my question a different way. I know how to change rgb to cmyk with photoshop, ID, Quark etc with no problems. Put that all to the side for a minute, Lets say a customer is creating a brochure 8 1/2 x 11. They use what ever program and have no understanding of rgb, cmyk etc. They send your company a pdf file that they think is ready to rock and roll. Without having to call the customer and get into all the changing of rgb to cmyk with photos, text etc. What is a nice way to change the entire pdf into cmyk without a huge shift(there alwyas will be some, less with photos) in color. Example, your rip will do it for you, a plugin for acrobat, the color profile you use. Hope this explains it better.

Thanks

 

[jmgalvin]

I've never had somebody send me a whole thing like that - expecting it to be print ready.

My guess is that it would be safest to place it into an ID document and then create a cmyk postscript file for Distiller. I guess you could do a straight cmyk pdf export out of ID, but I prefer the extra control that printing a postscript and running through distiller gives. Before I did that, I'd consider checking for any embedded profiles. If they're in it you could have some really goofy things happen.

The problem you run into is that, people who send you such garbage, usually have no idea of things like color management, etc. They'll compare the printed output to what they see on their, probably uncalibrated, monitor. Unless the gods are really on your side, there should be quite a bit of change. It's best to inform them that the entire printing industry works in cmyk, not rgb and that, if they don't have this capability, they should probably farm it out to ensure proper output.


Using OSX 10.3.9 on a G4

 

[ecm28]

You have to understand my company works with professional company's, designers(usually dont understand a printing press capabilities) and the public (really dont understand). We like to service all. If you get garbage then you need to deal with it the best way possible for the company and the customer. We try to help any way we can. Thanks for your advice

 

[jimoblak]

You can print professionally with RGB images if they have the proper color profiles assigned. 'RGB' is not a bad word in prepress if one knows what they are doing.

Assuming that your customer (or yourself) does not know what they are doing, you simply specify that jobs submitted in RGB without specifying (in writing) the color profile intent will be produced on your system with uncertain conversion results. There is little more that you can do. You cannot read the customer's mind if they did not have color management in mind to begin with. You cannot convert their RGB images any better than your RIP since both will alter the color from the original designer's idea. The customer should see a proof if they want proper color output.

Even CMYK images can produce color shifts if improper color profiles are used.

 

[MarcusStringer]

I like to use Enfocus Pitstop and convert the PDF in Acrobat, it's quick.

And anything It doesn't convert, like Some Vector EPS's, I can then open using the Touch up image tool which open the image or EPS in either Photoshop or Illustrator which I then convert to CMYK, save it, and close which updates the PDF then Ta Daaa

Marcus

http://www.midlandtypesetters.com.au

 

[ecm28]

This post was not in regards to how the printing industry works. Color proofs, color profiles etc. was not what I was asking for. I simply asked for tricks and tips to put it blunt for methods that others use when converting files. If using RGB images with correct profiles was a tip, then that was what I was asking for, not a explantion of submitting a color proof to the customer and blah blah blah. This is a nice forum and I enjoy posting here, i appreciate your comments fellas but your responses did not answer my question at all (except for Marcus).

 

[jimoblak]

I think you misunderstood the reply.

What is the best method ...for converting the entire pdf in one shot to cmyk without a major color change.

There is no answer to this question as there is no best method. You are always going to have color change when a client submits RGB documents with no profile data. You cannot escape this, even with a good program like Pitstop.

Color proofs, color profiles etc. was not what I was asking for.

Yes it was what you were asking for: color profiles are required for proper conversion from RGB to CMYK. Without color profiles, no $10,000 RIP is going to behave any better than a $60 inkjet printer from Walmart.

 

[ecm28]

jim, yes my question regarded profiles, but not that the customer intended this or that, if someone here used photoshop default 5 profile and had nice results, great. Someone used pitstop with a certain profile, great. Not trying to argue, i appreciate your comments and thank you. It seems your trying to expalin this and that about color and I'm not asking for an explanation. Simply, I use this with this and works out great for company time, money, and effort.

 

[jimoblak]

I was just confused why you would be seeking a best method to convert RGB->CMYK if you understood color profiles. Please excuse me if the details about proofing seemed condescending.

If you are looking for votes, I'll also toss mine in for Pitstop. Pitstop is very popular and everyone I deal with uses it. But that software will not always work great in RGB->CMYK conversion to your clients' expectations and it will not always save money, time and effort. There is no software that will do this. The ideal conversion software is not the variable to concern yourself with.