It would be tedious for me to go into this in depth on this list - I have
done it enough on the ACT list (where you can read Dans, Andrews and many
others opinions) . There are pros/cons to all decisions that we make -
tagging output ready CMYK files is no different.
I've participated in some of those discussions over the years and have changed my embedding policy as a result. There's a fundamental difference between CMYK and RGB that often gets lost in heated debates over pros and cons of embedding profiles in a color managed workflow that involves handing off files to third parties. With CMYK its not only possible, but likely to have multiple different profiles using different recipes of CMYK that describe the same device (press) behavior. All of the different profiles are perfectly valid for that press, but not necessarily appropriate for every image. That's not true of RGB and hence the need for very different policies regarding embedded profiles.
You might have several CMYK profiles that will softproof practically identically but they build separations using black ink in very different ways; and yet all will print well on a given press. Which method you use to build the black plate is largely dependent on the subject matter of the image and/or how you want it to perform on a press. For example, an image that contains uses a greater amount of black ink will show less color shift if conditions on the press drift a bit, but its more likely to show major density changes. Choose what best suits YOUR images. Or you might carefully hold critical shadow detail with a custom build of the black plate.
The bottom line is that if I've wisely built separations that I know should print well on printing conditions like I'm expecting the client to use, then I don't want to invite them to change my carefully crafted separations. Including an embedded CMYK profile does just that. Without an embedded profile they will most likely run the file with no changes at all. With an embedded profile, the likelyhood that someone will alter the file (intentionally or not) goes up substantially. In my opinion the disadvantages outweigh the advantages here. I've been bitten once too often where perfectly good CMYK files were altered (and hosed) based on an embedded profile. I use embedded CMYK profiles within my shop so that I can recall how an image was built and possible intelligintly repurpose it or better softproof it internally. Before CMYK images leave my premises, the profile is usually stripped.
Stripping the profile forces the receiving party to use and softproof the image based on their profile of their device without any alteration, which more often than not, is exactly what I want them to do. The only advantage of putting an embedded profile in is to allow the client to repurpose the image more accurately. Generally I don't want it repurposed or otherwise converted so not putting it in there is do downside. If the MUST convert to some other space (maybe for proofing), then using their assumed CMYK profile for their printing conditions will be plenty accurate because I've built my seps based on a good guess of their conditions.
If I have any question about whether or not my seps are appropriate for their conditions, I include a tagged RGB version of the image as well so that they can build their on seps from that if needed. I find I'm doing even this less and less these days... only in situations where I really have no clue at all about the CMYK printing conditions involved... as I've also found that including the RGB version is another opportunity for some color challenged production person to screw up a job. As bizarre as it sounds, in many instances (not all by any stretch), untagged CMYK that's a reasonable guess for the printing conditions involved is the safest file to hand off.
While the myriad of CMYK options seems confusing at first, you have to understand that within a given type of typical printing (not comparing newsprint to fine line screen glossy stock offset repro here), the variation from a press in one shop to the next is most likely FAR, FAR less than the difference between say Adobe RGB and sRGB and ColorMatch RGB. You are much more likely to encounter major surprises from misinterpreted untagged RGB files than with CMYK files destined for a known and reasonably common printing condition. You are also MUCH more likely to suffer ill effects from someone unintentionally converting your CMYK and screwing up the black plate than printing as is and suffering the natural differences between press A and press B that are running similar printing conditions. If the general printing condition isn't known and reasonably common then you ought to not be delivering CMYK files in the first place.
Bob Smith
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