Legend

質問

How to get what the client is seeing on her monitor to print

Forum|Forum|16 years ago
August 6, 2009
返信数 5.
24469 ビュー

Hello again!

I'm still working on these childrens books, and here's where I'm at.

I calibrated and profiled my monitor and the client's monitor.

The client has been merrily filling in the black outlines of her drawings in Photoshop. She picks the CMYK swatch that looks good on her monitor and fills in the drawing.

Now, I have on my computer a copy of her monitor profile. When I open her PSD images (which are in CMYK mode, with a generic coated SWOP profile), it seems to me that I should:

(a) discard the attached profile, preserving the CMYK numbers

(b) convert the image to the RGB profile of her monitor

(c) convert the image to the CMYK profile of the printing press (or perhaps back to a generic CMYK profile, since we don't yet know where we're printing).

Is this correct?

Or perhaps, when I open her PSD images, I should

(a) use the embedded profile (US Web coated SWOP)

(b) convert to the destination profile of the printing press

Any guidance appreciated,

Ariel

このトピックへの返信は締め切られました。

NB, colourmanagement

Community Expert

TaW,

Yeah Real World Photoshop is hard to absorb, I agree. It’s the bible, sure, but its not an easy job to absorb it. In your situation, rather than needing a degree in colour ;~} I think you just need to know about the bits that affect YOUR (and your clients) situation.

You've had some good advice here, CMYK settings are very relevant of course (and SWOP is outdated and totally irrelevant for European print). You client's monitor profile is not of any use to your computer.

I think there's one other thing that's really important that you need to consider.

How well does her screen show colour compared to a good printers proof? You need to know!

Calibration parameters can be badly chosen,

screens can be less capable than needed,

the room light can influence perception significantly.

Some of those can be optimised by adjustment.

How can you be sure of appearance?

Have a look here: http://www.colourmanagement.net/products/icc-profile-verification-kit

The printed work / proof should (must) be viewed in fairly bright daylight, in the print world that’s usually artificial daylight in a light booth.

The screen should be viewed in subdued neutral light.

You can't view a print next to the screen without a desktop light booth, because those 2 lighting requirements are incompatible.

And those requirements are inescapable.

Decent screen, good accurate calibration, proper viewing environments for 1:; screen and for 2: print and proof.

I hope this helps

if so, please "like" my reply

thanks

neil barstow, colourmanagement.net

[please do not use the reply button on a message in the thread, only use the one at the top of the page, to maintain chronological order]

A

Anonymous

Hi Ariel,

All the responses you are getting are correct, but really it comes down to this - A monitor is light (RGB) ink in paper is CMYK. Monitors should never be used to "Pick Colors" they can only simulate ink on paper. In my 30 years in color reproduction I seen many a client who has been bitterly disappointed and spent time and money correcting proofs because "it didn't look look that on my screen..."

If color selection is critical get a CMYK Pantone Books then you and the client will have a common reference to compare colors.

You then keep the CMYK % as prescribed by the Pantone Book.

I know its old fashioned but it works.... thats why Pantone is the success it is.

P

Printer_Rick

Inspiring

Wayne Pincham wrote:
If color selection is critical get a CMYK Pantone Books then you and the client will have a common reference to compare colors.
You then keep the CMYK % as prescribed by the Pantone Book.
I know its old fashioned but it works.... thats why Pantone is the success it is.

I understand this logic but it falls short. CMYK numbers alone do not define colors. They produce different results in different print conditions.

Ask any printer to proof a page of Pantone CMYK chips. Maybe a close match but not exact.

Even the books themselves are inconsistent.

Any CMYK swatches used in graphic design need to be evaluated in a color managed environment. This translates the CMYK numbers back into the destination CMYK color space, which is based on Lab values. Lab is the only color space that describes all the colors we see.

You can get away with choosing swatches in a book as a starting point, but the colors need to be proofed. Only then do you have a reliable color reference.

P

Printer_Rick

Inspiring

Lou beat me to it, his advice was very good.

It may very well be that leaving them US Web Coated SWOP v2 is the best route. When you mentioned a press profile, I assumed that the printer had supplied you with one. If that is the case then a CMYK - CMYK conversion is in order, as I mentioned before. DO NOT go back to RGB.

Whatever you do don't follow that first sequence. You mention discarding the attached profile, that's not a good plan. And don't use her monitor profile, that has no meaning on your machine.

You also mentioned:

The client has been merrily filling in the black outlines of her drawings in Photoshop. She picks the CMYK swatch that looks good on her monitor and fills in the drawing.

Please elaborate on "CMYK swatch" Are you referring to a physical swatch book, or swatches in Photoshop?

TᴀW作成者

Legend

Rick,

Thanks for you response.

I loaded up the Focoltone library into her swatch palette, and she's picking colours from there and using them in her artwork, based on the way they appear on her screen.

Since her monitor is calibrated and profiled, this should be fairly accurate?

TᴀW作成者

Legend

Arïel wrote:
"This conversion involves using Acrobat Pro (hope you have this
application)"
Yes I do. I can see what's coming: Tools>Print Production>Convert Colors (am
I right? )
That's a dreaded little dialog box right there. In fact, I've tried on
several occassions to use it to convert a colour pdf to greyscale, and it
always fouls up when it hits richs black (registration black). It will not
get rid of the numbers on the CMY plates. If you know how to fix that
problem, I'd love to hear!

Convert colors to Output Intent, and select your working gray profile

This converts everything to grayscale. If there is Device Gray, the number values won't change, but it will become calibrated.

And you are right, this tool is the best way to do CMYK - CMYK, you can enable "Preserve Black".

For example if everything was US Web Coated SWOP (ID, AI, PS), you would output from InDesign using PDF/X-4 with "Convert to Destination" Document CMYK

It is best to convert the colors in the PDF (I think) because there everything is composited into an output file. If all support files were set up properly, you will know that everything in the PDF is US Web Coated SWOP. You can convert to a new Output Intent using Acrobat. Then thoroughly check the entire PDF. The AI blue, the ID blue, the PS blue - they all need to be the same blue, right? Use Output Preview in Acrobat Pro to measure the values, you will know if all your colors are consistent.

"If there is Device Gray, the number values won't change, but it will become

calibrated."

Are you saying that rich black (100,100,100,100) is considered a device

grey? I still don't understand why Acrobat doesn't change 100,100,100,100

to 0,0,0,100 even when I choose a gray profile? I suppose it doesn't make a

difference for the press, because they're only printing the black plate. But

it causes a problem in that doing a preflight check for "Outputs more than

One Plate" throws an error?

P

Printer_Rick

Inspiring

Arïel wrote:
(a) discard the attached profile, preserving the CMYK numbers
(b) convert the image to the RGB profile of her monitor
(c) convert the image to the CMYK profile of the printing press (or perhaps back to a generic CMYK profile, since we don't yet know where we're printing).
Is this correct?
Or perhaps, when I open her PSD images, I should
(a) use the embedded profile (US Web coated SWOP)
(b) convert to the destination profile of the printing press
Any guidance appreciated,
Ariel

Your 2nd choice is better, much better.

Best case scenario would have been only one conversion, RGB - CMYK. But since it's already been converted to CMYK, it is best to do a 2nd conversion, to the profile that describes the true printing condition (the press profile you mention)

L

Lou Dina

Known Participant

Ariel,

If you want control over your color, you are going to have to learn the basics. Sorry, but there is no good way around it and it takes some study. I will try to give you a little guidance for now, but you need to read a good color management book, like Real World Color Management to get your arms around the concepts.

1. First, I will assume BOTH you and your client have properly calibrated monitors and that they are calibrated to the exact same parameters. If not, game over. You will never see on your monitor what she sees on hers unless this is true.

2. Your client needs to specify a CMYK working space to give the CMYK numbers color meaning. If she does not do this, then find out what her "default CMYK" is set to in Photoshop. If she has not picked a CMYK space, Photoshop will assume what is set under "Color Settings". Ideally, she would save her files with the CMYK profile embedded in the file. This makes it clear what she is using.

3. Once you know what flavor of CMYK she is using, then you should "Assign" that same exact CMYK profile to it when opening. If the file has the CMYK profile embedded when saved, you will know exactly what she is using, even if she doesn't know. Now, if all of the above have been done, you should see on your monitor what she saw on hers.

4. Until you know where you will be sending the file for output, leave the profile set to what she used. You should ask your printer for their specifications for file preparation....ie, color profile, resolution, ink limits, etc. After you have found out from your printer what they want, then you can address conversion, if required. They may want you to supply US Web Coated SWOP v2 files, and if that is the space you are using, then you should be done. Of course, you need to check resolution, verify that ink limits are below their maximum, etc.

Sadly, not all printers know what they are doing. Some are clueless about color management, profiles, dot gain, ink limits, etc.

Get the book or study the subject on internet sites. If you don't understand the principles, you will continue to struggle and your jobs may not turn out well. One other thing....insist that the printer provide a color "contract" proof of the job BEFORE it goes to press. If it looks terrible, something is wrong and you can catch it early and figure out what needs to be changed. If it looks great, then it is the printer's obligation to match the proof on press, within reasonable tolerances. Once you sign off on the contract proof, it should be set in stone (for both of you).

Lou

TᴀW作成者

Legend

Lou,

Thanks for responding.

First off, I have borrowed and read a copy of Real World Color Management 2nd edition. It's still on my shelf, and I'm trying to figure it out. But this stuff is confusing (and I have two degrees from a top British university -- but not in color management).

1. The parameters of our monitors are close, but not identical. I couldn't get her cheaper monitor dark enough. But anyway, our viewing environments are

pretty different. So I suppose I should just ignore what I'm seeing on my monitor (I'm not doing colour adjustments, just the layout etc.).

2. Her files are being saved with the default US web coated SWOP.

3. Okay, this is making sense. I think I went on a wild goose chase by asking her for her monitor profile. After all, when she chooses a CMYK number + a CMYK press profile (the default), we now have an "objective" colour defined (I guess that means a specific Lab colour?) And because her monitor is profiled, Photoshop knows what to do to get her monitor to produce that same Lab colour. And when I open that image on my computer, since my monitor is also profiled, Photoshop should know what to do to get it to produce that same Lab colour. So, if what I'm saying here is correct, the only thing I don't understand is why you said I won't be seeing the same colour on my monitor as she is on hers. And the only answer I can think of (please correct me if I'm wrong), is that our viewing environments are different.

So to summarize: I should simply let Photoshop "use the embedded profile".

Let me know if I'm not understanding this properly.

Thanks,

Ariel

L

Lou Dina

Known Participant

Ariel,

Yes...it is confusing at first. If you will be doing a lot of this, it is worth understanding. If this book is a one time shot, then maybe not.

I said IF your monitors are both accurately calibrated to the same parameters, you should see the same thing. But, if hers is calibrated to very different parameters than yours, you will see a different interpretation of the numbers on your screen than she does on hers. Yes, ambient lighting environment can have some impact, so it would be best if you both worked in a moderate to dimly lit environment.

Photoshop, being a color managed application, will see the monitor profile in the loop automatically and will instantaneously adjust colors as they are being sent to your monitor (and hers). So, all you need is an accurate monitor profile, and Photoshop will get the colors right. And yes, Lab is operating silently in the background as the universal translator. Your CMYK numbers, PLUS a correct color profile, are enough to identify the exact hue, saturation and brightness of a given color. Even though you may have a CMYK file on your screen, Photoshop is silently keeping track of everything in the background in Lab terms. Lab is the only color space on your system that is "device independent" and unambiguous. It doesn't need a profile, since it IS the standard. A given set of Lab coordinates always means a specific color, regardless of the monitor, printer or press used for final output. But that is not true of CMYK or RGB...they need a profile in addition to the numbers.

So, I think you have it now. Yes, let Photoshop use the embedded profile IF one is embedded. If one is not embedded, you need to find out what your client used, or what the default setting is in their Photoshop program, so you can ASSIGN the same profile to the file. You want your CMYK numbers AND your CMYK color space to match hers. Clear?

Lou

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