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The best way to convert an already-separated CMYK file to another CMYK output space is via a device link profile (in this case, one that is specifically built to effect a conversion between a source of coated Fogra 39L and a destination of uncoated Fogra 29L). With a properly-built device link, besides achieving a usually smoother-looking result, you can also control a number of parameters such as the purity of the primaries, black-only elements, etc.
Photoshop CS4 will finally be supporting device links, by the way -- a cheer to our gracious hosts at Adobe for finally doing something many of us had long wished for!
As for the more "traditional" way of converting between the two spaces (i.e., a straight ICC profile-to-profile conversion), the extra step of doing an intermediate conversion to AdobeRGB (or any other RGB working-space) is quite redundant, and brings no detectable advantages.
>>Photoshop CS4 will finally be supporting device links...<<
what you meen in "device links" i dont understand this paragraph?
a standard profile for CMYK contains all informations
for a mutual conversion CIELab <--> CMYK.
A device link profile for two profiles CMYK1 and CMYK2
replaces the standard workflow CMYK1 <--> CIELab <--> CMYK2
by one profile CMYK1 --> CMYK2 (for only one direction).
According to Marco, transforms by device link profiles
are smoother than traditional transforms (which goes there
without any proof, but it's indeed advertized by companies ...).
I'm using device link profiles for proof printing:
The input profile is for instance ISOCoated, the output
profile that of the proofing inkjet. The device link profile
is calculated once and applied very often during the calculation
of device pixels. Therefore it's fast, but concerning the
quality I don't see a difference, compared to proofing with
traditional calculations via CIELab.
Best regards --Gernot Hoffmann
and a last question: how do i now if i have possibility for devise link in my profile?
A devicelink profile is a special kind of profile. It is not 'inside the profile'. They are very handy but not common, and software like Photoshop cannot use it yet (may be CS4 can?). Some RIPs and high level printers do use them. Refer to the documentation of your machines if you don't know wether they can take advantage of them or not.
So with a devicelink profile, you can convert, for example, a document from an offset coated CMYK with 340% ink to an uncoated newsprint with 280% total ink preserving the black as pure black and some other details.
If you want to know a bit more, you may look for instance an on-line manual of Link-o-Lator
THANK YOU GUSTAVO!
I work for a company that wants to try their catalog printing on Finch #50 Opaque Smooth. This is a bright white uncoated stock.
I am planning to separate my images with the US web uncoated profile that Adobe supplies but I was wondering if perhaps some organization has profiled certain papers out there
and might have them available.
Anybody know of any such organization?
The profile for that paper would highly depend on the particular press that is being used. A generic profile for that paper would do you very little good.
Do you think it would be MORE generic than US web uncoated? or about in the same boat.
We are doing a test run but I cant convince some folks that the thing to do is make a custom
profile...so I am trying to come up with the next best thing. And, oddly enough, the printer
doesnt claim to be able to give us a predictable proof...jeez, what happened to the concept of
Anyway, I am having to make the best educated guess. any ideas?
thanks for the input
Well you do have some problems there. If you're going to the trouble of an actual press test, why not throw a target on there and make yourself a profile. Cross render it to your Epson and have the pressman run to the same densities for makeready. That will likely get you very very close, with a bit of fine tuning.
Really, any profile you decide to try is going to be as good a guess as anything else, as long as it's designed for uncoated stock. There's no way to know without further testing whether one is better than the other.
If you don't have access to profiling equipment, I can read a target for you.
thanks...thats exactly the way I see it but there are realities to working for a company
where others dont see it that way...if ya know what I mean.
Well, I am still trying to get the profiling approach approved. I use profilemaker 5.0
and have a DTP41 and Eye one handheld spectro.
What kind of equipment,charts and software do you use?
Same software but I've had a Spectrolino T for the last ten years and as long as it works I see no need to replace it.
Have you done full blown offset press profiling before? I had done alot of profiling of proofers etc but not a real press. If I get to do it Ill share my results with ya.
I've used someone else's press measurements for one of the printer's I use on a regular basis, and that worked out very well. Most of the time I profile the proofer, but in this case, the person who set up their Oris proofer ran targets on press so I just used his data.
When you say "profile the proofer" do you mean creating a profile from a chart that was output on the printer and then using that data to create a full blown press destination profile?
...Or just using that profile for proofing etc.
The European style depends much on standardized
(averaged) press profiles (FOGRA, UGRA, ECI).
I found this by a Google search
'Dolezalek' & 'Press profiles':
Dr.Dolezalek had written much about, but not everything
is available in English.
The underlying idea is this: if I make today an actual
profile for a press, then this will be of no value two
weeks later. Because the press can be adjusted not only
globally but also per inch of width, the outcome depends
on the temperature, the humidity, the actual image
content, the actual settings across the width and so on.
Therefore the FOGRA/ECI profiles were created - it's
mostly possible to adjust a press so, that an inkjet
proof based on e.g. ISOcoated-v2-eci.icc can be
reproduced by the press (and the press operators).
In other words: the press operators get an inkjet proof
and then they are trying to adjust the press.
The inkjet proof has to be validated by printing and
measuring the FOGRA 'media wedge', which consists of
a couple of discrete swatches or patches.
Best regards --Gernot Hoffmann