Assign Profile vs Converting to Profile

[Printer_Rick]

This relates to a very lengthy thread in the InDesign forum, "RGB vs CMYK images and resolution"

I have a lot of questions (perhaps confusing) relating to RGB color gamuts. To simplify let's start with 2 gamuts, ProPhoto and Adobe RGB

I have a profile editor that can view both of these within potato-shaped Lab gamut. They are of course both triangles, I believe all RGB gamuts are. I can see ProPhoto is considerably larger than Adobe RGB, containing more fringe colors

I also see that the gamma of Adobe RGB is 2.2. The white point is 6500K

The gamma of ProPhoto is 1.8. The white point is 5000K

I understand gamma to be "black point". Or better yet "black density". On a press sheet, ink density can be measured with a densitometer. In my experience a density reading of 2.2 on a press sheet would be very dark. Is my understanding correct - that gamma (RGB) is comparable to ink density (CMYK)? Perhaps better to state as an analogy: Gamma: RGB as Density: CMYK

My monitor RGB profile has a gamma of 1.8 (mac standard). This tells me that the Adobe RGB gamma of 2.2 has to be re-interpreted on my display. Is that correct?

As for white point, that would be the RGB equivalent of CMYK paper white.

The InDesign forum has a lot of discussion about assigning profiles, vs converting to profiles. My understanding is that assigning a different RGB is actually a "pure" conversion. The pixels are left completely intact. There is no move to Lab, and back to RGB. It's taking the image and effectively dropping it into a brand new gamut, The price for this, of course, is that the appearances of the colors are completely redefined, and this appearance shift can at times be radical.

For example, if I have an ProPhoto image open, then assign Adobe RGB, I can see very clearly that the image becomes darker on-screen, and the color "shrinks"

As a prepress person, I have often used re-assigning in RGB mode as a very effective color correction tool. Usually it's turd polishing, to be quite honest, when critical color match is not an issue. The scenario is usually a crappy sRGB image. I assign Adobe RGB, which as the Adobe description states is ideal for conversion to CMYK. I must add that I always use proof preview, I am well aware that Adobe RGB has colors far beyond a standard CMYK gamut. But when I convert to CMYK, using Adobe RGB as the source, the image color is expanded, and the result on press is often vastly improved.

I will also add that as a prepress person, I don't go re-assigning in this fashion without the customer's consent.

In the InDesign forum, this "re-assigning" has been referred to as "random color". There is a lot of emphasis on color appearance, and maintaining color appearance. The consensus therefore is that if you had an sRGB image, you should convert to Adobe RGB. But then it is my understanding that you miss out on the often huge benefit of gamut expansion. If you wanted to expand color after converting, you have to do color corrections, which alters the pixel data and in the strictest sense is destructive (unless you use adjustment layers).

All this leaves me wondering - if assigning is such a no-no, why is it available? Probably the main reason for the assign capability is to assign profiles to images that don't have an embedded profile. Sometimes users unknowingly discard profiles, if the color settings policy is set to off. When another user open the image, he quickly sees the image does not have a profile.

Normally he would assign his working space, since that is affecting his visual on-screen appearance. But he can't know for sure if that's true to the original capture.

Which brings up another point. Any device doing the capture (camera or scanner) has a gamut. This gamut is an input profile.  When the image is translated from device capture into digital file, should this input profile be embedded in the image?

At this point I'm not sure about this. I have a 7.1 MP camera, and the downloads always have sRGB embedded. Not a profile specific to the Kodak model. My guess is that sRGB is a universal standard, representing the gamuts of monitors and desktop scanners. It is the working space of the world wide web. So it's more or less the default RGB, and is also the default working space in all Adobe applications (North America general purpose).

But the description of sRGB is very clear. It is not ideal for prepress, this is stated in Adobe's description. It is small. This may make it comparable to CMYK, but it is still not ideal for conversion to CMYK. And in fact there are CMYK colors that fall outside of sRGB. Especially if you are dealing with the larger CMYK gamuts corresponding to new offset screening technologies (FM screening and concentric screening)

So why in the world would someone convert from sRGB, to Adobe RGB? There's no benefit at all. May as well leave it sRGB, instead of converting. And the even bigger question - how do you know that sRGB is "true" color? To me, the true color is the original subject. In the case of a photo, that might be just a memory. In the case of a scan. it's the original, but the user might not even have that, if someone else did the scan and all he has is the digital file. So who's to say that the embedded profile - sRGB - is a fair representation of the original?

Re-assigning RGB profiles may be an odd way of adjusting color. But it can be effective. Why would the assign option be readily available, if not to translate colors to a different gamut, without altering pixel data? Seems to me it is the primary reason Adobe developed the assign option in the first place.

I know this is a lot of questions. Any input on any of these matters would be greatly appreciated.

[Printer_Rick]

Mike,

Have you or anyone else seen how big FM and Concentric gamuts can be, compared to conventional screening.

[Mike_Ornellas]

DYP

I know Chris Cox's job is a real ball buster and the things that he has to deal with are a cutting edge continuos headache. Im not saying that any Engineer is a slacker. I'm saying that Adobe's focus when it comes to features and  implementations lacks true important focus to better the application for the majority of users.  They fear screwing up the majority for what is seen as a minority group. People that share files and print.

Marketing pushes way too hard to add their two cents to the equation to promote sales without really understanding the markets they serve. I can say with confidence that print has been left in the F-ing dirt - yet EVERYONE prints at some point and to multiple outputs and shares files with others.

WTF?

am I wrong?

[Mike_Ornellas]

Have you or anyone else seen how big FM and Concentric gamuts can be, compared to conventional screening.

Yes. I deal with printers in India as well as China who use different ink-sets from the US.  Euro or Toyo sets along with Stochastic and hybrid screens and sizes is quite the bitch to deal with - especially when you try and explain to the customer that our proofs match our files, but will mean nothing to the people in another country.   Man I love Singapore USA workflows......

Comcast jobs comes to mind...

yea right....

and then someone will say....

"that's not the responsibility of the software and color managment"

and my rebuttal will be, then make the software geared towards repurposing instead of trud processing.

[Printer_Rick]

Mike,

First of all thanks for all the advice so far, it's good to learn a design perspective. Hope I haven't asked too many irrelevant questions...

When it comes to high end screening, would you agree that the problem may not be the CMYK numbers? In my experience a US Web Coated CMYK (which most of my clients use) can produce a very good result on press, so that tells me the separation isn't the problem. It's Photoshop thinking the gamut is smaller than what it is, which screws up the soft proof.

(Numbers are the same, appearance changes... maybe I've come around to the original subject.)

Also relating to color management and communication breakdown (cue Led Zep), the consensus seems to be that the problem is the Destination CMYK prepress selects may not be ideal. So can we dig deeper - which of the following best describes the conversion problem:

1. You want to use a specific CMYK profile for a job. You are afraid that if you supply RGB, prepress will pick the wrong one.

2. You prefer a certain rendering intent (perceptual) but prepress will use something different (relative colorimetric)

3. To get good CMYK color, you need more than RGB-CMYK. You need RGB-CMYK, then CMYK color correction to get the desired result.

By the way has anyone looked into the Adobe RGB gamma change in post 93? I'm thinking a similar process could one day be utilized in a CMYK context...

[Miguel_Curto]

I would have to say none of the above.Prepress are ussualy the place where hicupps hapen,most of the time theres someone who messes up profiles in handdesign or whatever...but not because the file was submitted in RGB.I would say that shift induced by wrong color management would be greater in a "bad" conversion/assigment from RGB to CMYK than CMYK to CMYK.

CM is simple its people that make it complicated.The agencys/magazines I have to submit files to most of the time think they have to be in control and dont even let me speak to the printer.People are afraid of what they dont understant and most of the time they think you are going over their heads...

[Printer_Rick]

Miguel Curto wrote:

I would have to say none of the above.Prepress are ussualy the place where hicupps hapen,most of the time theres someone who messes up profiles in handdesign or whatever...but not because the file was submitted in RGB.I would say that shift induced by wrong color management would be greater in a "bad" conversion/assigment from RGB to CMYK than CMYK to CMYK.

CM is simple its people that make it complicated.The agencys/magazines I have to submit files to most of the time think they have to be in control and dont even let me speak to the printer.People are afraid of what they dont understant and most of the time they think you are going over their heads...

Miguel,

I want to make sure I understand correctly. Are you saying the common mistake is the designer converting to CMYK using his own judgement, instead of either a. getting a printer to supply a CMYK profile or b. leaving files as tagged RGB, and letting the printer do the conversion?

Also I'm not sure about your reference to CMYK - CMYK conversions. To be clear most files I receive are CMYK. I do not re-convert these. My proof is calibrated to press, but the file sent to proof honors the customer CMYK number values. I am certain this is standard practice. In the rare event I re-convert a CMYK for press or paper reasons I have to tell the client first, because they expect me to leave their CMYK alone. I am right about this, correct? Anyone with a design perspective, please tell me if they believe it is common practice for prepress to mess with supplied CMYK.

PeterK wrote:

Of course there is! That's what ICC profiles are for! The entirety of the above post makes it very clear that you haven't even begun to scratch the surface with colour profiles. Yes, some colours are not reproducible on press and they will get dulled down, and all of that is dependent on the printing variables, which stock, line screen, rendering intent you chose, etc. but then your display will show that to you in the soft proof! You are the same person who thinks it's alright to be haphazardly assigning profiles to "colour correct" images, right? I guess you could do that, but the reasons why you would do that over using the tools in Photoshop meant for the purpose are beyond me. Read more on colour management, particularly on creating profiles and soft-proofing them. You'll save yourself a lot of headaches. (this is of course, after suffering a few while learning the subject)

Peter,

I understand what you're saying. To clarify I will say that most files I receive are already CMYK. To be more specific, US Web Coated (SWOP)v2. I don't know what others think of this profile, I think it usually produces a good result on press. This tells me that the CMYK numbers pose no problem. The problem is the display. The easy solution is to give a more accurate CMYK profile for the customer to use for conversion, then the display would be true. But the problem is a designer may not want to use a CMYK specific to a certain printer, the job could end up going to another printer. And the other problem is, you can't knock the Web Coated they like - the result is usually good. This seems like a display issue to me, somehow using Web Coated ink values (since they work) and profile tag, but just changing the gamut for soft proof appearance.

I could also choose to do a CMYK-CMYK conversion. But I'm very reluctant to do that, usually the customers are very pleased with the result when I leave their CMYK intact. Do you feel CMYK-CMYK is the way to go? I don't believe that is standard practice.

And no I don't haphazardly assign profiles, that's not my workflow. But if it makes a low quality image look better, with no change to pixels, is it not valid? Yes I use Photoshop color correction tools, but re-assignment can provide a good starting block if the image needs a lot of help.

[Guest]

Rick -

I might be wrong, but based on the questions you've been asking in this thread, I'm thinking that you're not fully invested in an ICC-based color managed workflow. (And BTW, thank you for asking the questions and putting up with the sometimes less-than-charitable responses you've been getting. It continues to blow my mind that genuine curiosity is so often met with a poke in the eye.)

Stochastic screening (or whatever you're using instead of traditional halftone dots):

Yes, the gamut is larger in the mid-tones and 1/4-tones (although somewhat smaller in the 3/4-tones). This is easily reflected in an ICC profile built to reflect your press conditions. Give that profile to a client, and they can accurately soft-proof the ultimate result.

"Some sheets look great, other sheets you say - 'What's the matter with the file?' "

Again - a good ICC-based color managed workflow keeps surprises to a minimum.

And on and on...

The book I mentioned to you was printed on the other side of the country by a printer I'd never worked with before on a sheet I'd never used before. 164 images - all full-color. I talked to the prepress department, got the profile that described their press conditions, converted everything to CMYK and proofed each image on my proofer, then sent the files off to them. They randomly selected 20% of the images to proof on their proofer, sent those to me, and they were a dead match to my proofs. I flew across country for the press check which went like this: First pull on each of the 11 forms on a big-ass Komori web press was right-on. Sign-of and proceed. 8,000 copies of a 268 page book in 6 hours.

This experience is my norm now. My day job is shooting annual reports - mostly sheetfed on #1 sheets. When it comes time to print the annuals, it's first pull 80-90% of the time. And I have very picky clients (and I'm even worse.)

I looked at your equipment list - it's all high-end sheet-fed on really nice presses. I bet those Komoris are capable of far more gamut than you're getting out of them without even messing around with exotic screening. We call it "leaving all the crayons on the pressroom floor."

First step is to implement best practices. Then you can fuss around with all the fringe stuff.

One more thing:

As I think I underlined in a previous post - CMYK is exclusively a business medium. If you tell your boss that you have a way that he can save money and make his clients happier, you will have his full attention.

So here's some data from the field (it's in the book):

A small sheetfed operation that I interviewed (about $15M per year) was humming along nicely when they made the decision to move to a full ICC workflow - in fact, they decided to become a G7 Master Printer. The one-time, upfront investment to calibrate their presses (yes, it can be done) cost about $15k. In the first year after implementing this system, they saved $200k. The savings was in less waste, shorter make-ready, and less on-press time. Slam dunk.

[Printer_Rick]

Maybe this better explains what I’m trying to say:

RGB numbers alone do not make colors. CMYK numbers alone do not make colors. They only make colors when they combine with a defined gamut. Correct?

What if you could change the gamut?

RGB. Gamut change. Numbers preserved. Appearance changes. CMYK result changes.

CMYK. Gamut change. Numbers preserved. Color separation preserved. Display appearance changes. CMYK output unchanged. Press appearance matches display appearance.

This is all about the color gamut. The pixels don’t get changed. If the gamut change were available as an adjustment layer, you could even restore the original appearance.

Design perspective in RGB - change the gamut. Numbers stay the same. Wow, that looks better. Let’s go with that. This is sometimes (not always) achievable with re-assignment. Yes, it is pedestrian, but there are pedestrians who use the software.

Design perspective in CMYK - change the gamut, depending on the printer they will use. Wow. This is what it looks like at Shop A, with this type of paper, and their screening. This is what it looks like at Shop B, with this type of paper, and their screening. There is no change to the profile tag. There is no change to the color separation. As long as the ink limit is correct for the stock and press, there’s no need to reseparate. Yes, if appearance is critical, a CMYK-CMYK conversion is in order. But for the time being the designer is flipping through print options, nothing more.

In Ps there is limited gamut control available now. What if a user could more easily alter the gamuts, and leave the pixels alone? Instead of the other way around?

Maybe Adobe has considered this, maybe not. I believe it could be a useful feature. It’s a very simple concept. I think an average user could understand it. Soft proofs could become more accurate, and color communication might be a little easier.

Thanks to everyone for their contributions and information, and have a nice weekend.

[Guest]

RGB numbers alone do not make colors. CMYK numbers alone do not make colors. They only make colors when they combine with a defined gamut. Correct?

Well, kind of.

Stated a different way, both RGB and CMYK are device dependent.

i.e., RGB triplets by themselves do not define an absolute color. Only when they are expressed in a specific color space (Adobe 98, ProPhoto, sRGB, etc) do they describe a specific color. Likewise, a CMYK build does not describe a specific color. Only when you express them in a specific color space do they describe a color.

What if you could change the gamut?

I think you may confusing "gamut" and "gamma". A few posts back, you asked about what happens when you change the gamma of a profile from 2.2 to 1.8. That's gamma (think of it as contrast), not gamut (color volume.)

I'd advise against going down the dark hole of manipulating the gamma of a profile as an image correction technique.

For CMYK, you can't really change the gamut. When properly built, an ICC profile will describe the exact gamut of the output device (the press.) It is what it is, and you work within that constraint.

RGB. Gamut change. Numbers preserved. Appearance changes. CMYK result changes.

CMYK. Gamut change. Numbers preserved. Color separation preserved. Display appearance changes. CMYK output unchanged. Press appearance matches display appearance.

Your description is a bit convoluted, but again, stated a different way:

RGB > Assign Profile > Numbers preserved > Colors change > CMYK changes.

This is broken color management. As soon as you Assign a profile to a correctly tagged (profile embedded) RGB, you have changed the color away from what the image provider intended. Not good.

[EDIT - In your quote, you use the term "change gamut". In my restatement, I use the term "Assign Profile." Essentially the same thing.]

CMYK...

I can't really follow your chain here. But where you want to be is as follows:

RGB > Convert to CMYK using profile that describes your press conditions > Proof on your profiled HP > Into the imagesetter > Onto the press > Color matches soft-proofed RGB and proof.

In Ps there is limited gamut control available now. What if a user could more easily alter the gamuts, and leave the pixels alone? Instead of the other way around?

No, no, no. Too much user manipulation available already. Again, the gamut is fixed and determined by the physical device (proofer, press, etc.)

Soft proofs could become more accurate, and color communication might be a little easier.

This is already built into the software we all use. ICC-based color management. The way to accurately soft-proof color is to use an accurate ICC profile of the ultimate output device. I do it every day. In a press room scenario, the ultimate output device is the combination of press/RIP/screening/ink/paper.

[Miguel_Curto]

Printer_Rick wrote:

. CMYK numbers alone do not make colors. They only make colors when they combine with a defined gamut. Correct?

Plz go to  (in Photoshop) Edit -> Color Settings

In CMYK roll-down choose custom CMYK to see what defines a CMYK profile.

a CMYK profile is a given combination of Press+Inks+Papers.If you change one of this factors then you need a new profile.

Gamut comes from that combination.OR did you mean gamma?That too comes from that combination and you can see that in the curves response.

Im sry if this seems somewhat paternalist (not my intention).

[Printer_Rick]

Miguel Curto wrote:

Plz go to  (in Photoshop) Edit -> Color Settings

In CMYK roll-down choose custom CMYK to see what defines a CMYK profile.

a CMYK profile is a given combination of Press+Inks+Papers.If you change one of this factors then you need a new profile.

Gamut comes from that combination.OR did you mean gamma?That too comes from that combination and you can see that in the curves response.

Im sry if this seems somewhat paternalist (not my intention).

Thanks Miguel. First, I did mean gamut.

I think my explanation is falling short, this is a difficult idea to convey. Basically what I'm saying is that CMYK gamuts are not determined by an image file.

Think of it like this - the same image, screened 2 different ways, printed side by side on press. Same paper, same ink. One uses conventional screening, one uses FM. The color gamuts are quite a bit different, even though the file and the profile tag were the same. I have seen this myself and I know it is true.

I definitely understand Rick's workflow explanation as the best scenario: RGB -  Press CMYK - Calibrated Proof - Plate - Press (which matches display and proof)

My problem is the RGB - CMYK part. Most files I receive are already CMYK. There's no reason to change the CMYK, the customers love what they're seeing on press. What I meant was leaving the CMYK numbers intact, and changing the on-screen rendering.

I guess Rick is right though, it would probably lead to more confusion. The fact that I can't explain my idea (my fault) means that it probably wouldn't be understood by the average user.

[Guest]

Think of it like this - the same image, screened 2 different ways, printed side by side on press. Same paper, same ink. One uses conventional screening, one uses FM. The color gamuts are quite a bit different, even though the file and the profile tag were the same. I have seen this myself and I know it is true.

I definitely understand Rick's workflow explanation as the best scenario: RGB -  Press CMYK - Calibrated Proof - Plate - Press (which matches display and proof)

My problem is the RGB - CMYK part. Most files I receive are already CMYK. There's no reason to change the CMYK, the customers love what they're seeing on press. What I meant was leaving the CMYK numbers intact, and changing the on-screen rendering.

I guess Rick is right though, it would probably lead to more confusion. The fact that I can't explain my idea (my fault) means that it probably wouldn't be understood by the average user.

Rick -

You are explaining it clearly. The problem is that the CMYK files you're receiving have been separated into CMYK from RGB using a profile (SWOPv2) that doesn't describe your press conditions. You're employing a screening technology that gives you a larger gamut than the one described by the SWOP v2 profile.

Do your clients a favor and supply them with an ICC profile of your press conditions. Tell them to use that profile for jobs headed for your shop. Only that way will you be able to take full advantage of the expanded gamut your company bought when you installed the Concentric system. Right now, you really are leaving crayons on the pressroom floor. The ICC profile carries all the information you're trying to tinker with on an a la carte basis.

ICC-based color management.  It really does work.

RIck

[Printer_Rick]

Rick McCleary wrote:

Rick -

You are explaining it clearly. The problem is that the CMYK files you're receiving have been separated into CMYK from RGB using a profile (SWOPv2) that doesn't describe your press conditions. You're employing a screening technology that gives you a larger gamut than the one described by the SWOP v2 profile.

Do your clients a favor and supply them with an ICC profile of your press conditions. Tell them to use that profile for jobs headed for your shop. Only that way will you be able to take full advantage of the expanded gamut your company bought when you installed the Concentric system. Right now, you really are leaving crayons on the pressroom floor. The ICC profile carries all the information you're trying to tinker with on an a la carte basis.

ICC-based color management.  It really does work.

RIck

Thanks for the explanation Rick.

It looks like I'm at a fork in the road. I definitely see the benefit in a more refined ICC workflow. Responsible color preservation. The problem is that with concentric our customers are saying they just love it. I want to give them our CMYK, but I'm afraid many wouldn't know how to use it if they had it. And if they did, there's a chance the result might not be as popular.

The one thing confusing me a little is the crayons on the floor. Are you saying I'm not getting my whole gamut? Our colors are saturated on press, the depth is amazing. I could change the separation (ink percentages in shadow, black generation, dot gain settings, UCR), but it's still CMYK, 0-100 each channel.

Again thanks for your time, I will definitely look in your book for more answers

I'm by no means a printer expert by I always assumed that any variation in the printer would be adressed in the profile.I never looked at it that way but if screening introduces such a wide change then I guess you would need a diferent profile for each type os screening.Thats one more reason not to mess with CMYK unless your in the printers end.

As I understand profilling each combination of screening+inks+paper+printer could be quite expensive,so maybe profilers use a estimate for this?

RGB -  Press CMYK - Calibrated Proof - Plate - Press (which matches display and proof)  - Sure is the right way to go, but you have to be realistic about matching on paper what you see in monitor.Even with soft-proof youre seing transmission light not reflective as in paper.Not to mention that unless  youre in the printers end you'll have little information about profiles used and just maybevyou dont even know if coated or uncoated (most of the time I dont).

Miguel,

The screening makes a HUGE difference. I have seen conventional and concentric and FM all on the same press sheet. As I stated above the customers love the new screening technologies.

And you are right, the more variables you introduce, the more profiles you end up with, the more chance for confusion and error. It works, but the mantra is "proceed with caution"

As Rick states above my best course of action is to supply customers an ICC profile. The funny thing is that no customers have asked for it, and there are so many designers on all different levels, it would be a great effort to get all of them to use a special CMYK profile. I am afraid that one might use it, and another wouldn't. If both users worked for the same agency, and used the same RGB image, I can see a different conversion and press result being an issue.

Maybe this is a classic "if it ain't broke don't fix it" situation, since the customers are happy. But I will still try to communicate this issue to them. Thanks to everyone for your help.

[Guest]

Maybe this is a classic "if it ain't broke don't fix it" situation, since the customers are happy.

Perhaps.

But there might be money to be saved on your end by instituting a solid and sound ICC workflow - even G7.

Transition is always hard. You're on a moving train. Jumping from one car to another always involves pain. It's just a matter of if your boss thinks it's worth it.

In any case, I'd do a bunch of research before you start mucking with your system. Go beyond this forum. Talk to other printers who have made the change.

[Mike_Ornellas]

Buy you have to agree Rick that CMYK environments are far more critical of color when evaluating very slight variations in light tones. When dealing with this area of print, color management somewhat falls apart in expectations and most expect color management to deal with this area well when in fact it may or may not. Usually not.

[Guest]

Mike Ornellas wrote:

Buy you have to agree Rick that CMYK environments are far more critical of color when evaluating very slight variations in light tones. When dealing with this area of print, color management somewhat falls apart in expectations and most expect color management to deal with this area well when in fact it may or may not. Usually not.

Sure. But isn't that more an issue of press room process control than color management? You know, how stable and repeatable the press is?

That said, I agree with you that selling color management as the be-all and end-all that will solve all problems is a bad idea. There are other factors to consider.

[Mike_Ornellas]

Take the press drift equasion out of the mix and utalize something like a much more predictable half tone proofer such as a Creo Spectrum or Kodak approval which are far more stable for color conversion evaluation. You will then see the true limitations of color management in simple terms. Every custom profile needs editing but it's rarely done. All these issues comes down to tolorance.  Some have higher expectations then others. The major problem is the marketing pin heads who hype the product without fully understanding the technology.  I have extra bullets for some people at X-rite and Adobe....

[Guest]

OK, it's Miller time for me. We're hitting the road.

Everybody have a safe and enjoyable Fourth of July.

[Guest]

The one thing confusing me a little is the crayons on the floor. Are you saying I'm not getting my whole gamut? Our colors are saturated on press, the depth is amazing. I could change the separation (ink percentages in shadow, black generation, dot gain settings, UCR), but it's still CMYK, 0-100 each channel.

Yes, that's what I'm saying. If you are using a stochastic screen and the files coming in have been separated for a dot screen, there's no way you're getting all the color your press is capable of giving. It may look good now, but it can be better.

[Miguel_Curto]

I'm by no means a printer expert by I always assumed that any variation in the printer would be adressed in the profile.I never looked at it that way but if screening introduces such a wide change then I guess you would need a diferent profile for each type os screening.Thats one more reason not to mess with CMYK unless your in the printers end.

As I understand profilling each combination of screening+inks+paper+printer could be quite expensive,so maybe profilers use a estimate for this?

RGB -  Press CMYK - Calibrated Proof - Plate - Press (which matches display and proof)  - Sure is the right way to go, but you have to be realistic about matching on paper what you see in monitor.Even with soft-proof youre seing transmission light not reflective as in paper.Not to mention that unless  youre in the printers end you'll have little information about profiles used and just maybevyou dont even know if coated or uncoated (most of the time I dont).

[Chris Cox]

As I understand profilling each combination of screening+inks+paper+printer could be quite expensive,so maybe profilers use a estimate for this?

If they have an accurate proofing system, then they can profile that.  Usually the printer/press comes out of the equation once it's been linearized.  That does still leave screening+inks+paper, and possibly platesetter type (positive dot, negative dot, DTPlate, DTPress, etc. affect dot gain - but usually only one type is in use in a given shop).

Not profiling the combinations means that the customer will have no idea what their output might look like.  That's generally a bad thing.

[Mike_Ornellas]

Different screen sets, angles, dot shapes and sizes all play a part in the optical representation perceived by humans as well as densitometers. Color management works.  Some workflows work better then others. There is also a point of diminishing return where you are trying to get that extra 2% accuracy and you wind up messing up something else. Again, color management works, but expecting it to be some kind of plug and play pipe dream, you are wasting your time. It has its limitations. It will get you closer faster. I will not solve all your problems.

[Guest]

Mike Ornellas wrote:

There is also a point of diminishing return where you are trying to get that extra 2% accuracy and you wind up messing up something else. Again, color management works, but expecting it to be some kind of plug and play pipe dream, you are wasting your time. It has its limitations. It will get you closer faster. I will not solve all your problems.

I tell folks that by following just the most basic best practices, you'll get 95% results 95% of the time. And that's a whole lot closer to happiness than a non-stop parade of "Oh my god, what happened to the file?" jobs.

ICC-based color management in a process-controlled workflow. It works.

That last 2% is always elusive (and expensive), regardless of what system you use.

[Was DYP]

am I wrong?

No, your not wrong at all.

I was just pointing out (though it does not belong in this thread) that there seems to be the option out that there PSCS5 (a 64-bit) is going to be something wonderful, when the facts/comment from those at Adobe seem to point otherwise. I big letdown coming I believe.

[Mike_Ornellas]

We need 64 bit processing for many different kinds of work that Photoshop does.  The problem is that Adobe is not a hardware manufacture and has to deal with an outside entity all the time to support their product.  That in itself is insane...