GCR and Profile conversion Advice

[rickyticky]

I work in PrePress and we have a Prinergy Connect Version 5 workflow. We currently use the colour settings shown in attached file (Current.pdf) which converts CMYK images and graphics from ISOcoated_v2_eci.icc to ISOcoated_v2_300_eci.icc. This is mainly done to control TAC (also saves us on average 3% ink usage).
What we are looking to do is change this setting as can be seen in attached file (Proposed.pdf) so that we convert images and graphics from ISOcoated_v2_eci.icc to coated_FOGRA39_GCR_bas.icc. I have tested this through the workflow and got as far as proofing but not had the opportunity to run press tests yet. We are seeing an average ink reduction of 10.5% which we are very happy with as it does not involve any financial outlay which is out of the question at the moment. We have visually compared the proofs, and measured lab values in certain of the files and are very encouraged, but I feel we are missing something as this seems to easy?
We would only carry this out on selected PDFs that we know have been created to our usual spec (generally PDFx-1a with a SOcoated_v2_eci.icc output intent) so in my understanding the conversion should be OK. Is this the case?
Also other elements are not affected (text, frames and fills,etc....)

One more quick question, I believe the ISOcoated_v2_300_eci.icc profile has some sort of GCR in it but I cant find the details on this do you know?

Thank you for taking the time to read this

[TerryWyse]

I think it's safe to say that all "modern" CMYK ICC profiles use GCR to one degree or another....mostly not a question of IF but HOW MUCH GCR is applied. UCR is so *80s*. :-)

Couldn't help but notice that you have your preferences set to override all embedded ICC profiles. While I can possibly understand why you might do this for CMYK, why would you do this for RGB images? I guess if it were me, I'd choose to *honor* embedded RGB profiles...but in turn I would set my default (for untagged graphics) to sRGB. And seein' how your rendering intent choices don't seem to include a check for black point compensation, I'd be changing the RGB rendering intent to perceptual to avoid clipping.

Just sayin'

:-)

Regards,
Terry

[rickyticky]

Thanks for the reply Terry,

I take your point about the embedded profile and the RGB conversion. The RGB in this part of the workflow is pretty much irrelevant as we are almost always supplied CMYK PDFs and most are PDF x-1a. If we do get any RGB images then they are picked up and handled in the initial preflight. But I will check the rendering intent settings for this.
What I am trying to do here is reduce ink while keeping colour consistent in images that are already CMYK, and would like to know is converting from ISOcoated_v2_eci.icc to FOGRA39_GCR_bas.icc.
I would only do this when I know the images in the original file had ISOcoated_v2_eci.icc embedded