object with only filling change to open path after PDF export

[Asterixx]

hello,

I use a version before CC so perhaps this has been corrected, but: when I create some shapes that are just fillings (like circles or painted fillings) and save as PDF (not matter which), and open this PDF in some other vector software (Affinity Designer, Inkscape) this object is then an open path because the start/end node is not one single node anymore but TWO :). Is this a known issue and does it matter for printing?

Also the other way around by the way: if I create such a shape  in Designer or also in CorelDraw and open it in Illustrator, then Illustrator says the path is open and finds two anchors instead of one.

First I thought this is because of my old version of Illustrator, but it's also the case from some newer software to each other.

[Monika Gause]

Please save such a PDF and share it on the forum.

[Asterixx]

thank you, I will do - but actually my goal is not really to defend my old CS4 usage, because it's really old :). But it would be more interesting, probably also for other users, to know if this is still the case today with the newest CC version.

As mentioned it's not about a large complicated drawing but only about 1 object, a simple circle without outline but only filling. Perhaps somebody with the new CC version could confirm that a circle saved as PDF can be opened by other software like Inkscape and Designer normally or also as open paths with double anchors.

Also the other way I can't really test here as there is no Illustrator CC trial version (without signing a contract). So it would also be interesting if a PDF with the circle from CorelDraw e.g. can be opened in Illustrator normally.

[Asterixx]

Here as promised the file. It reads as open path in Affinity Designer and in Inkscape.

Interesting: it reads correctly in CorelDraw althouth the other way around a circle from CorelDraw as PDF reads in Illustrator as open path :).

Is all this still today in Illustrator CC the case?

And (perhaps even more important) is the concept of start/end anchor and closed paths important when I just do normal printing (no cutting) and don't need further editing?

[Ton Frederiks]

This one is a closed path.

For normal printing it should not make a difference, open paths are valid objects.

Why other apps see it as open, I would ask that in their forums.

[Asterixx]

yes I just created it as closed path. I never thought a second about this that a simple circle could be read differently after exporting a PDF (today in 2024) depending on which vector software you use. And it's not "those other products" as e.g. a simple circle created in CorelDraw is opened in Illustrator as open path while it is not opened that way somewhere else.

Does the PDF format understand the concept of start/end anchor anyway?

[Monika Gause]

I can reproduce that with your file in Inkscape and Affinity Designer. When you draw a circle in Affinity Designer and then open the file in Illustrator, the path is closed.

You maybe want to ask questions about the PDF file format in the Acrobat forum. 

[Ton Frederiks]

The PDF fileformat can have closed paths. 

I did an experiment, saved a circle as PDF, without Illustrator editing capabilities.

When opened, the circle became an open path with 5 points.

A rectangle stays a closed object with 4 points.

So yes, a circle is interpreted as an open path. Why? I leave that to someone else to answer.

[Asterixx]

This is very interesting, thank you very much. Just to know: so you used the Illustrator CC and reproduced a circle and exported as PDF (e.g. PDF/X) and then the path is open?

Yes, the additional point is because the start/end point becomes two points over each other.

And another question to you: how did you get then the information about the path after export, in Illustrator or is there any way to read this from a PDF elsewhere (like in Acrobat or any preflight)?

(yes Monika, also a little bit a Acrobat question but I would like to keep the context here together, and as Ton Frederiks showed it's perhaps even more an Illustrator topic)

[Ton Frederiks · Accepted solution]

Yes, I saved the circle as PDF and unchecked Illustrator Editing Capabilities to make sure that the PDF part was used during opening.

I closed the file and opened the PDF.

Using Window > Document Info with Selection Only and Objects, you can see the number of points and if the path is open or closed.

I also created a circle in InDesign, saved as PDF, opened in Illustrator and got 5 points and an open path (although the opening was at the bottom instead of to the right).

[Asterixx]

Thank you again! Very interesting findings and I did not expect them to be still there in Illustrator CC today (and InDesign). I thought this was more a problem of different tools (like CorelDraw vs Illustrator).

Yes, when I save the circle in Illustrator as X-1a then the path is open as well with one more point.

Interesting that from Affinity it seems to export closed paths. From CorelDraw open paths as Illustrator.

This is such an easy object (circle) that I am surprised that it does not seem to be a known issue for Illustrator users. And that lets me think that it does not matter in terms of printing. But it would perhaps matter for some cutting, engraving. In those cases open paths should not happen, but the editing PDF option is probably not the most often used from Illustrator.

[Ton Frederiks]

When editing it makes a difference, but for printing it does not matter if the path is closed or open.

I don't know about cutting, but when the start and end point are the same location, what could go wrong?

[Asterixx]

I don't know anything about cutting 🙂 and engraving, I just mentioned it as a possible use where there could be a problem. Just to emphasize that even if for me and you and others, who only do printing, it does not matter, it still is an issue. Illustrator (and CorelDraw e.g.) have some code implemented that changes the export of a simple circle concerning the number of nodes and the open/closed path question - just depending on which file type (PDF type) you choose. Perhaps this is because of the PDF specification and indeed this would be a question to PDF expert. But as for me it is more important to understand if this is normal or common behaviour of Illustrator and other vector software and if it matters for printing, I asked here in the Illustrator forum and appreciate if it is dicussed here.

[Monika Gause]

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@Asterixx  schrieb:

I asked here in the Illustrator forum and appreciate if it is dicussed here.

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Sure. But some of the people with more in-depth knowledge of the PDF file format and all the available pre-press tools might just not frequent this forum.

[Asterixx]

Yes, for questions about prepress and PDF specification that's a good idea.

So to continue here with the Illustrator issue :). Most of the time when delivering to a customer, probably a PDF version is chosen which does not allow too much editing. At least me, mostly I deliver X-1a. When more editing is needed, also *.ai.

When a customer absolutely needs closed paths, I can't deliver a non-editing PDF from Adobe (InDesign, Illustrator). So then I would have to deliver e.g. *.ai. When he does not know anything or need anything about the paths and it's only about printing, then I could deliver a non-editing PDF.

Is this change of the path and creation of a hidden additional anchor in the PDF export really a new issue to Illustrator users? I did not find any information on Adobe sites or discussions by search engine. And if so: seems to be a good sign that all those many PDFs created the last decades with open paths have not made any problems in printing :).

(By the way I also asked the Corel community and there this also seemed to be new, and the export of PDF from CorelDraw should work fine though, while it's not intented for editing anyway.)

[Asterixx]

I checked and saw that indeed this is only the case for fillings (at least in my test). So a normal curve / outline / path withouth filling, it's exported normally as close path, alhtough there also is a start/end point. It does not seem to be related to this. But I don't know why the filling with a path around should be different. I also asked in the Acrobat community about the specification but no answers yet.