Save As Adobe PDF includes "hidden" sublayers!

[sPretzel]

Hi,

In Illustrator, when a layer is hidden (visibility off) but a sublayer within that layer is not (sublayer visibility on), the layer and every sublayer it contains are not displayed. However, when this Illustrator file is Saved As>Adobe PDF, it seems that information from the sublayers is still saved into the PDF file. Whether the sublayers are indeed present (viewable or retrievable) in the PDF file, I don't know, but the resulting PDF file size indicates that some or all the information from the hidden layer and its sublayers are included in the PDF.

I have created the attached file to show this issue. The pdfsizeissue.ai file contains two layers: Layer 1 contain a square with drop shadow, Layer 2 contains type. Here are the various scenarios, saving the Illustrator file as Adobe PDF ("Illustrator Default" settings except for "Preserve Illustrator Editing Capabilites", "Embed Page Thumbnails", "Create Acrobat Layers from Top Level Layers" all unchecked):

1- All layers are visible. File size: 498KB, pdfsizeissue_allvisible.pdf

2- Top Layer 1 hidden (Layer 2 visible, Layer 1 invisible, sublayer <Path> in Layer 1 invisible). File size: 504KB, pdfsizeissue_toplayer1hidden.pdf

3- Sublayer in Layer 1 hidden but Layer 1 top level visible. File size: 81.9KB, pdfsizeissue_sublayer1hidden.pdf

4- Layer 1 top level and sublayer <Path> in Layer 1 both hidden. File size: 88.2KB, pdfsizeissue_alllayer1hidden.pdf

To complete the picture, I am adding two more scenarios:

5- All top level layers are hidden but not the sublayers. File size: 499KB, pdfsizeissue_alltophidden.pdf !!

6- All top level layers and sublayers within are hidden. File size: 58.7KB, pdfsizeissue_allhidden.pdf

I was unable to attach pdfsizeissue.ai so I saved it as Adobe PDF with Illustrator Default settings and attached that as pdfsizeissue_savedaspdf.pdf

The expected outcome is that when Layer 1 top level is hidden, then every sublayer within Layer 1 acts as if it was also hidden and does not affect PDF file size. So I would expect scenario 2 file size to be the same as scenario 4 (88.2KB, not 504KB).

This is for CS4 but likely applies to later Illustrator versions too.

There is another thread discussing what seems to be a similar topic. I am under the impression that the proposed solution in that thread does not work, as reported by another user.

https://community.adobe.com/t5/illustrator/saving-illustrator-as-pdf-without-the-hidden-layers/td-p/...

Questions:

1- Can other folks reproduce the issue with the attached file?

2- Is there a setting in Save As that would correct the issue?

3- How can I view what information from the sublayer makes it into the PDF? The PDF looks as expected (what I see on the PDF looks like what I see in Illustrator). I cannot find the "hidden" objects from the sublayers in the PDF. The only indicator that there is a problem and that those objects are the likely cause is that the PDF file size is much bigger than expected. They account for the increase in file size but are unaccounted for in Preflight. Where are they in the PDF file?

Any help would be welcome. Thanks.

[Kurt Gold]

You probably forgot to include the attachment, I'm afraid.

[sPretzel]

Hi Kurt. It was in process. The files are attached.

[Kurt Gold]

I do see the inconsistent behaviour you are describing, though I get different values (kb).

I cannot explain the differences and I'm pretty sure that only Illustrator engineers with a profound technical knowledge about the .pdf export mechanisms may enlighten the case.

Unfortunately, Teri Pettit is not there anymore. Most of the time she was able to explain why certain things do work as they have to work (technically).

[sPretzel]

Thanks for taking a look Kurt. I suppose you mean by "getting different values" that you reproduced the issue with the original .ai file and generated .pdf files according to the scenarios described. The values I wrote were taken from the files themselves so we should read the same value if you examine the .pdf files I provided.

This is bad. PDF files in real designs can get pretty big for no reason, just with these hidden top layers (scenario 5 shows that I can get "paper weight" when saving as PDF since the .pdf file is an empty page). I hope other forum members or Adobe engineers can answer the questions I ask at the end of the post.

[sPretzel]

Hi Kurt (or anyone who could help). One aspect that puzzles me is that, for example, in the file for scenario 5 (pdfsizeissue_alltophidden.pdf), I cannot find any of the hidden objects in PDF. Preflight indicates there is nothing in the PDF. How can I know if the objects are indeed in the PDF file or if the increase in file size is due to something else (artefact, other information related to the hidden objects but not the objects themselves, erroneous file size due to the Illustrator > PDF conversion etc.)?

Of course, this wouldn't solve the issue but it would be helpful.

[Kurt Gold · Accepted solution]

Yes, by "different values" (file sizes) I meant that I created my own .pdf files based on the original file that included the .ai portion. I think the reason is that I used the latest version of Illustrator (not CS4).

However, I do see the discrepancies and I wish I could explain them. But I can't.

My guess is also that it might have to do with some (superfluous, but harmless) data that gets written into the .pdf file during the export process, but that is pure speculation.

Maybe you can make a side trip to the Acrobat forum and post a link to your request? This way, you can perhaps lure a knowledgeable Acrobat engineer who may explain the issue.

[sPretzel]

Hi Kurt. I did post about it on the Acrobat forum earlier today, with a link to this thread!

In the example I provided, the size difference between files was small but rhe difference can get very very large, depending on what and how much is hidden.  If layers are hidden in AI but turn out to be retrievable in PDF, size set aside, it may be a concern.