Publisher v2.0.4 ; export using PDF/X-1a:2003 ; max ink control ?

[laurent32]

 Is there a way to easily have control over the max ink parameter ?

Or is there a strategy included in the export procedure when using PDF/X-1a:2003 (mostly dedicated to CMJK printing) ?

[loukash]

Isn't it controlled by the ICC profile?
Like ISO Coated 300 which – as the name suggests – limits total ink to 300 %.

[laurent32]

I need to learn more about it…

We often apply profile because we're asked to… without knowing all about them…

Max ink parameter is very important…

I think @lacerto has knowledge to share here…

[lacerto]

Obsolete.

 

[laurent32]

On 2/25/2023 at 6:18 PM, lacerto said:

Yes, and the TAC limit basically works when converting RGB content and placed CMYK content that has embedded profiles conflicting with the CMYK target profile and is not set to pass through (e.g. AI files with embedded CMYK profiles). Notice here the difference to Adobe InDesign, which by default always discards embedded CMYK profiles and just passes through the original CMYK color values.

Basically the ink limit is applied based on hosting file's ICC whenever the color values need to be recalculated, whether the affected objects will be in vector or raster format, or become rasterized during the process.

This can get really complex, since PDFs placed to be passed through will not have their colors affected, unless there is a "compatibility conflict" (= Affinity thing) and the affected files will be rasterized. Also, overprint status of objects in AI files will be ignored, and in version 2 apps placed AI files will always be rasterized (a bug, most probably).

Because of the complexity, it is best to see that native objects defined in CMYK are simply just within the recommended TAC (since native objects, when exported using the document CMYK color profile, will not be affected by the TAC limit), and that placed CMYK files do not have excess ink usage (as files that get passed through would not be affected), so in practice only native RGB objects and placed RGB files (primarily raster images) will be affected.

Here are two demo PDFs using ISO Coated 300 v2 and ISO Newspaper profiles, where the second page has a conflicting CMYK AI file. The first page has CMYK defined objects demonstrating how ICC based TAC limit does not affect native CMYK color definitions. The bottom circle is in RGB 0, 0, 0 black and when converted shows the ink limit of the profile. The second page is partially a mess because the overprint status of placed objects is lost, but the page demonstrates that the hosting file's ICC will limit the maximum ink usage of files that have conflicting ICC embedded (so the host file with ISO Newspaper ICC will limit ink usage of placed ISO Coated 300. In both situations colors of the second page are translated because of the profile conflict. 

isocoated_300v2_tacdemo_v01.pdf 26.87 kB · 5 downloads

isonewspaper_tacdemo_v01.pdf 26.86 kB · 5 downloads

Thanks @lacerto, I'll need to read carefully, things are getting very complex with all the possibilities we have…

Knowing that I'm exporting to PDF/X-1a:2003, using CMYK format document (apub) with undefined color profile yet, would you say :

- I can use RGB files with undefined color profiles ?

- I can use RGB files with defined color profiles that would match the color profile I would set to the apub document ?

I prefer to work with RGB files because because 40% of my work is for print and 60% is for web…

My print goes to rotary printing (45g/m2 paper) ; what color profile for the apub document would you suggest ?

- Just to be safe, I generally convert PDF to RGB pictures before printing, would you not do the same ?

[lacerto]

Obsolete.