Unexpected results when flattenning a document

[Sotir25004881oiei]

I'm trying to flatten a PDF document full of live transparencies, shadows and such elements and I would appreciate your help.

I get strange results. The content is device gray, but during the flattening, some objects convert to RGB, which I noticed in Print Preview.

I noticed in Flattener Preview that the transparency blend space of the document is sRGB, so I changed it to device gray and I tried to flatten again, but again I get strange results. The shades of gray change and again some objects convert from device gray to something else.

I admit that the document is messy, but I'm not sure is that the culprit or maybe something else. The document was made in Indesign and then it was exported as sRGB and it was edited and converted to grayscale in Acrobat by using third party plugins.

It's messy, I know, but this document has already been used for printing of a book with satisfactory results, so it works.

It's just I'm not sure where I will print the next run, so I'd like to avoid nasty surprises by flattening the content.

There are different printers and you never know what can happen. Better to do this by myself than to leave it to the printshop, cause once I had a bad experience with this.

So please tell me:

1. How to flatten the document properly? Should I use the Flattener preview?

2. Will this rasterize the vectors, shadows and such elements?

3. How should I set the transparency blend space?

4. I was also considering converting to an earlier version of PDF/X by using the preflight. But what confuses me is that PDF/X has this thing "output intent" and I'm not sure whether this will affect the colors on paper in some way (I mean the shades of gray actually).

The current settings in my Flattener preview are:

Preset: High res
Raster/vector balance: 100
Line art and text res: 1200
Gradient and mesh res: 300
Conver text to outlines: unchecked
Convert all strokes to outlines: unchecked
Clip complex regions: greyed out
Preserve overprint: checked

Thanks

[JR Boulay]

1. Yes

2. No

4. The output intent is a metadata, it will no change anything in the document.

3 :

[Sotir25004881oiei]

Thank you, but unfortunately this does not work in my case.

After changing the transparency to Gray Gamma 1.8. and after flattening, some objects become calgray. They get Gray Gamma 1.8. tags and they visually "stick out" in the design in Print Preview.

I also saw some artefacts between them and the rest of the objects (in cases where they touch each other or where they partially overlap).

Whenever I notice artefacts, I turn off smoothing in Preferences>Page Display, and the problem usually goes away, but not in this case.

I think that I found a better solution, but I'm not an expert and maybe this is not a wise thing to do:

By using 3rd party plugins I attach an ICC profile to the objects. In this case it's a grayscale profile (same for all the images).

Then I change the transparency blend space to that profile (so it matches the profile of the images). After flattening, the result looks nice and all the images look uniform and they are all tagged with the same profile.

Here and there I saw some artefacts, but after turning off smoothing in Page Display, they are gone, so I assume it's safe. If necesary, in the end I can remove the ICC profile from the images.

It's important to note that I haven't checked the whole book yet, I just tested this on some extracted pages.