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Author Topic: CMYK problems  (Read 3812 times)
Jonathan Ratzlaff
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« on: June 26, 2003, 07:44:01 PM »
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In photoshop make sure you have the image set up with the proper profile for cmyk and assign that profile to the image.
You also need to ensure that the cmyk profile in pagemaker is the same as the printer requires.  
Are you sure that pagemaker is actually displaying the image or just a preview of it.
Using indesign, you have a choice of the graphic previews available to you.    
Generate a pdf with the profiles and see what the colour looks like
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Digi-T
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« Reply #1 on: June 28, 2003, 03:16:51 PM »
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Thanks for all of the responses, they are very helpful. I clearly have a lot to learn about this part of the process. For my current project I am definitely going to keep, at least the images, as RGB until I know what printing company is printing the job and what their requirements are. If they insist that I do the converting to CMYK than I will try to find out why. I can see the importance of knowing exactly what printers they will be using and with what color profiles. Based on my last experience it is clear that not every printing company shares the view that they do the conversion process themselves.

I'm not certain if I am only seeing a preview in Pagemaker but I suspect I am since I am not familiar with Indesign so I obviously am not using it. I'll be looking into that as well.

I'l have to look for the books in the bookstore and see if that helps me some more. Thanks again.

T
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digitaldog
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« Reply #2 on: May 20, 2005, 11:56:38 AM »
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I can't see the problem with offering an RBG TIFF now in place of what used to be a tranny.

If the RGB file is correct on my screen it is, ipso facto, the reference image. So, it should be equally valid on the printer's monitor.

Whether or not I should go one stage further and provide a CMYK conversion is another issue.

The fundamental point stands, that the RGB is as good as the tranny.

This is really all about changing working practices and a resistance to same.

D.
-->If the RGB file is correct on my screen it is, ipso facto, the reference image. So, it should be equally valid on the printer's monitor.

Youíre making a LOT of assumptions. First, that the people at prepress are using calibrated and profiled displays (which many are not), that they honor the embedded RGB profile in your document and most of all, that they have a good conversion process (an ICC output profile). Any or all failures of the above will produce ugly conversions and output. The image you see on your screen is not any bit representative of the output device until someone soft proofs the image using an output profile. And even then, thatís a stretch from a contract proof that someone is contractually agreeing to match on press. So while this can work, there are a lot of leaps of faith in the above assumptions.

RGB is not as good as a trany because RGB is a device dependent colorspace composed of a huge pile of numbers. Numbers alone donít define how a color appears. You can have a dozen different sets of numbers that produce the same color appearance. You might need a dozen different sets of numbers to produce the same color output. A transparency IS the reference media. Itís not ambiguous as long as you view it under the right illuminant (a daylight box). High end drum scanners produce an on-the-fly conversion to CMYK, almost always optimized for the output device (press or contract proof) the shop is aiming for. The resulting CMYK numbers are the correct recipe of numeric values to match, as close as possible within the confines of color gamut and the skill of the scan operator that transparency. This isnít anything like an RGB file.

With proper color management in place and knowledgeable people, RGB can be as good (or better) than a transparency. But thatís assuming a lot!
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Andrew Rodney
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Digi-T
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« Reply #3 on: June 26, 2003, 01:54:00 PM »
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I know this topic may be a stretch for these forums but it does still involve photography and I'm certain that someone out there can help me make some sense of this. Here's the deal. I'm doing some design work that requires working in CMYK in Pagemaker for the final printed material. As an example, I worked on an RGB photo in Photoshop to prepare it to be placed into Pagemaker for the cover graphic. I converted the photo from RGB to CMYK and there was no noticable shift in color in Photoshop. However, when I placed the photo into my Pagemaker file the color shifted noticeable and undesirably. Thinking I could fix this color problem I assigned a color profile (photoshop 4 or something like that) and it looked much better in Pagemaker. I thought maybe I had my problem solved but when I briefly talked to the Printer about my concerns he went into a lot of technical jargon involving the need for using color swatches and even changing my color profile on my monitor when I am in CMYK mode. I found it very confusing and I wasn't in a position to discuss the issue at length with the Printer at that time. I don't yet have a color matching system with swatches and I am very uncertain about changing my monitor settings because I have it set very accurately for RGB and matching to my printer. Are these steps really necessary? One of the reasons for my confusion was that a test sample of the document looked closer to the Pagemaker file than the more accurate Photoshop file. It seemed from talking to the Printer that it shold have really been the other way around. Anyways, any help or easy to understand resources regarding this issue would be appreciated.

T
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AJSJones
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« Reply #4 on: June 26, 2003, 06:04:50 PM »
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If your monitor is well calibrated, as I suspect, you could investigate "soft proofing" as a way for PS to show you what your printed output would look like - IF you can get an appropriate profile from the printer. He suggested "even changing my color profile on my monitor when I am in CMYK mode" perhaps this offers some hope that he might indeed have such a profile, and you would put it with your other profiles and select in when you select your "proof set-up"
That's how I do the final tweaks before I print to my Epson 7600 (following Bill Atkinson's advice, since I use his profiles).  My response here is predicated on being able to use similar logic in your situation...

Hope that helps, and let us know how it turns out!

Andy
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Rainer SLP
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« Reply #5 on: June 26, 2003, 08:16:59 PM »
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Hi Digi-T,

I once made a calendar also in Pagemaker and asked the pre-press manager if I should convert into CMYK and he said, It is not necessary. This is done by him and then he makes the negaitves for Offset.

So are you really sure that you shoul already make the conversion? to CMYK?

If you like everything in RGB it should be OK. Ask the responsible of making the negatives if it is really necessary that you deliver him the CMYK file.
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regards Rainer

please visit www.rsfotografia.com


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Dan Sroka
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« Reply #6 on: June 27, 2003, 11:43:28 AM »
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I agree with the others: RGB to CMYK conversion is best left to the printer (the person, not the machine). Not only is it esoteric, it is also very specific to their equipment and needs. If you do it, and the color on press is bad, it will be your fault, and your dime to fix it. Have the printer handle it: they will give you a press-accurate proof to approve, and then it is their job to make sure the final prints match this -- whatever it takes.

I worked in prepress for years, doing this kind of work. And there was nothing worse than a client giving me a file that he converted himself.

Dan
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Dinarius
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« Reply #7 on: May 19, 2005, 09:20:03 AM »
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What I would like to know is what are the typical adjustments one might make in a CS softproof of a CMYK profile in order to make it the same as the RGB?

I have just shot an image of an oil painting and the only difference between the RGB and the CMYK on my screen is the lack of 'gloss', 'sheen' or 'lustre' (if you get my drift!) on the CMYK image. In all other respects, it is identical. Info palette readings are the same, contrast is equally 'punchy'. It is simply that the CMYK looks a bit dull or flat.

The best way I can describe it is this; if I could lay a sheet of clear cellophane over the image, it would give it exactly the lift it requires.

Get my drift?

Any ideas?

Many thanks.

D.
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digitaldog
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« Reply #8 on: May 19, 2005, 12:15:25 PM »
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Some of the worst most heinous color Iíve ever seen were from print shops that were provided RGB data. Many have no idea how to convert RGB to CMYK since they were controlling this in the past at the scan stage. I donít know how many seminars Iíve done where I've made a custom CMYK conversion for a shopís contract proof, did a conversion from RGB to CMYK using that THEN sent the shop a tagged RGB file (something not earth shattering like ColorMatch RGB) of the same file. Side by side you canít believe some of the awful butt ugly RGB conversions these guys create.

Andrew Rodney
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Andrew Rodney
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« Reply #9 on: May 20, 2005, 12:08:27 PM »
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-->So what do you think? What is the "digital standard" a printer should be expected to work with?

Thereís no such beast.

What would make everyoneís life easier is if printers really would print to some standard press conditions. Thereís SWOP but thatís real ambiguous for most printers. They all say they print to SWOP standards even when they are printing sheetfed which of course is a big fat lie. Itís what they expect customers to accept and walk away. If you look at conventional photo processes, we have standards. Look at E6 processing. Sure, you can send a dozen pro labs the same exposed shot and they will vary, a bit. In a perfect world, every transparency would be identical. This is not a prefect world. However, the differences and fudge factors seen with all this film is relatively small. Now look at just the printers who say they print ďSWOPĒ. Itís all over the planet. Thatís because by and large, printers donít want their customers to assume that they print like the guy across the street. Then the only competitive advantage is cost. SWOP isnít a standard to aim for, itís to be exceeded! This is chaotic.

Now look at what the SWOP committee had done. They have VERY precise and explicit descriptions of SWOP. They have a specification that is as precise as 928 color patches that all have an exact spectral (LAB) value. Itís called TR001 SWOP. That is, if you were to measure these patches on a press that is really producing SWOP as defined by this group, you could measure all the color patches and have an exact spectral match. The U.S. Web Coated (SWOP) v2 profile in Photoshop is SWOP TR001. IF (huge if) you know a press is conforming to TR001 SWOP, you could convert the data using the Photoshop profile and get awesome output. Problem is, who really is aiming for this standard? All printers say they print SWOP, but are they? Thereís a similar standard for sheetfed being worked on called  DTR004 for Commercial Sheetfed Printing. Again, if printers would conform to such a standard, producing really excellent CMYK conversions would be a snap.

BTW, this isnít something that canít and is not being accomplished. There is something like a dozen different newspapers in Europe who all print to a standard and supply a profile that reflects all those press conditions. Itís doable but in the US? Itís not easy.
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Andrew Rodney
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Dinarius
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« Reply #10 on: May 20, 2005, 01:30:47 AM »
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I can't see the problem with offering an RBG TIFF now in place of what used to be a tranny.

If the RGB file is correct on my screen it is, ipso facto, the reference image. So, it should be equally valid on the printer's monitor.

Whether or not I should go one stage further and provide a CMYK conversion is another issue.

The fundamental point stands, that the RGB is as good as the tranny.

This is really all about changing working practices and a resistance to same.

D.
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AWeil
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« Reply #11 on: June 26, 2003, 05:04:00 PM »
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CMYK to print is indeed a complex process. The way I usually avoid the re - (or shoul I say de- ) calibration of my system is to 1. Use only dedicated pantone colors for decorative purposes - they have numbers and will be controlable and 2. include a controlstrip on the edge of the image/graphic - either a grayscale or a rainbow of the usual colors, 3. insist on color proofs in the the CMYK mode (cost extra, but is worth it) and tweek the material accordingly. In additition: 4. To ensure the desired color output, I will be there, when the first print-run is made: Last chance to chance any casts. Just as in inkjet printing you are talking of a prefect match between colors and paper. Each medium takes on color differently. And 4. Rest assured, even experienced printers have trouble with correct color transfer. It's a mix of craft, art and experience - one of the most difficult tasks in the business. Only dedicated reproduction specialists can do it right - and even them only most of the time - not every time.
Good luck!
Angela
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sergio
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« Reply #12 on: June 26, 2003, 08:55:10 PM »
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Color management to CMYK presses can be esoteric practice even for experienced printers. It is impossible for you to understand it in a simple thread and there are no shortcuts. Get Bruce Fraser's books which are great. Read REAL WORLD PS7 and COLOR MANAGEMENT. They take a lot of time and energy, but they really throw some light into all this. You can get those at Amazon doing a serach under his name.
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« Reply #13 on: May 19, 2005, 02:29:45 PM »
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Andrew, and others,

Back in the "old days" I could give a printer a slide and they would take it from there. My area of knowledge stops at the slide, and I wouldn't have it any other way.

Now there are too many choices. So, if we assume the slide was the standard of exchange between a photographer and a printer back in the "old days" what is the standard now, given that my knowledge stops at approximately the same place?

I would prefer to give printers an RGB, tiff file. Based on what others have said in this thread, and my own experience I think a printer who knows his stuff should be able to work with this.

So what do you think? What is the "digital standard" a printer should be expected to work with?

Michael
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Michael Canyes
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« Reply #14 on: May 20, 2005, 01:43:17 PM »
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WOW, that's pretty grim!

Given the choice of rolling up in a ball and waiting a few years for standards to evolve properly, and making a living shooting, I guess I will continue to stick to RGB, tiff forrmat and fight the good fight with the printer if I have to.
Michael
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Michael Canyes
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