PDF 1.6 exported from Large Size Canvas is incorrect PPI and also wrong scale when viewed in browser

[liamdmcl2]

I'm using Illustrator 27.1 working in a large-size canvas and trying to export some 11" x 8.5" artboards with the PDF 1.6 export setting (as reccomended by the Known Issues article). I've tried exporting using both the "Save As" and "Export for Screens" optons, and I'm experiencing 2 issues:

Issue #1 - The ppi of downsampled / compressed images is a lot smallet than what's set. If a Downsampling ppi is set for Color Bitmap Images in the PDF export settings, the ppi in the exported PDF is a lot smaller (I'd assume around 10x smaller). I'm only getting crisp images at the max ppi of 2,400.

Issue #2 - The PDF is 10x smaller in some viewers. So far, I'm having this issue in Chrome, Edge, and Preview (Mac). I don't have the same scaling issue when viewing it in Acrobat, Gmail, Google Drive, or when importing it into Illustrator.

This issue should be replicable with any large-sized canvas, but I've attached the exported PDF with all settings left at the [Illustrator Default] except the downsampling ppi is set to 300.

Thank you in advance for your help!

[Monika Gause]

If it's OK in Acrobat, then it's OK.

Other PDF viewers don't support everything in a PDF.

[Ton Frederiks]

If I copy your file and paste it into a new 11" x 8.5" document, there is no problem with your settings.

The large canvas document you shared shows indeed a low res image in Acrobat, while my normal canvas size copy shows a high res image result. 

It looks like a bug with the Illustrator export to PDF.

You may want to mention it here:

https://illustrator.uservoice.com/

[liamdmcl2]

To update here, I've spoken and screen shared with Adobe Support regarding these issues and they've provided the following information:

Issue #1 - The ppi of downsampled / compressed images is a lot smaller than what's set. Adobe Support has agreed this is a bug with the Large Size Canvas and reccomended I follow the workflow of exporting at the artificially higher ppi.

Issue #2 - The PDF is 10x smaller in some viewers. Adobe Support claims this is an issue with the Chrome, Edge, and Preview PDF viewers. Since it's 3 different PDF viewers from 3 different companies, I'm not convinced they're entirely to blame, but there's really nothing I can do.

[Ton Frederiks]

It is good to hear that Adobe support confirmed the bug (only getting crisp images at downsampling 2400 ppi ), but I would recommend to report it on Uservoice to keep track of the possible solution status.

Issue #1 - The ppi of downsampled / compressed images is a lot smallet than what's set. If a Downsampling ppi is set for Color Bitmap Images in the PDF export settings, the ppi in the exported PDF is a lot smaller (I'd assume around 10x smaller). I'm only getting crisp images at the max ppi of 2,400.

[Met1]

I don't understand why you are using "Large Size Canvas" when your item is 8.5x11...

From the FAQ on Large Size Canvas troubleshooting Adobe Help page:

Why does my large-scaled artwork (.ai and .pdf) shrink on opening in a reader app or a browser?
When you save or export the .ai or .pdf documents created on a large-sized canvas, a scale is applied on the document. On opening this artwork if your reader app or browser is unable to read the scale, the artwork will appear ten times smaller.

[liamdmcl2]

Fair enough re: the scaling issue being listed as a "known issue".

In my specific situation, I'm designing a series of full wall-size murals. Each wall is over 200" W x 120" H. I've illustrated these murals at 1:1 scale on a Large Size canvas, so that when I send them to print, there's no confusion about the scale. I'd like to send someone a PDF proof package that they can print on standard 8.5x11 paper, review, and provide feedback. So I've saved each of these 1:1 scale murals as a Symbol and placed scaled-down copies of the Symbols on a series of 8.5x11 artboards. I then save these artboards as the PDF proof package. When the client provides feedback, I can edit the 1:1 scale murals, and it automatically updates in the proof package.

I often need to design large-scale prints in 1:1 scale and send proofs, so having the PDFs appear properly is important.

[Test Screen Name · Accepted solution]

Here is what I believe to be happening. It's complicated. I oversimplify a lot, below, and it's still complicated.

* Acrobat has a page size limit of 200 x 200 inches. But it also supports a PDF feature called UserUnit, which allows pages to be scaled. So for example if the UserUnit is 10.0, then a page size of 50 x 50 inches is really 500 x 500 inches.

* Illustrator 24.2 added support for this feature. Before than Illustrator was fully limited to 200 x 200 inches too,

* In Illustrator 24.2 you can create an artboard up to 2000 x 2000 inches. If the artboard is over 200 x 200 inches, a UserUnit of 10.0 is set. (The only UserUnit Illustrator ever uses is 1.0 or 10.0). 

* Not a bug, but an inconvenience. If the artboard is over 200 x 200 inches, the UserUnit is always set to 10.0, even if exporting a PDF that is much smaller. (THIS IS HAPPENING IN THIS CASE).

* Some PDF viewers will ignore UserUnit and show a PDF 1/10 of the size. This is not a bug, it's probably a PDF viewer made for older PDF versions before UserUnit. A lot of apps and plug-ins will ignore UserUnit too. 

* A bug. UserUser is ignored in setting the ppi for raster effects. The consequence is that if making a PDF from a document with a large artboard (over 200 x 200 inches), then the raster effects are at 1/10 of the specified resolution. Nasty.

This is nasty and I strongly recommend you just avoid artboards over 200 x 200 inches. It does not matter that you are exporting smaller page sizes, the artboard size has done the damage.

[keithb40008408]

So, was there ever an actual answer or fix to this issue? I have been using Illustrator for years and I am just starting to have this issue. I prepare work in Illustrator nd export it as a press quality pdf with printers marks. I exported a document on a 37" X 61" artboard this morning and had no issies. I tried the same thing on another artboard, this time 31" X 21" and I get the "10X Smaller" warning and the file that is generated is useless. These artboards are no where near 200" X 200". Has Adobe ever solved this issue?

[Ton Frederiks · Accepted solution]

You may want to add your vote here :

https://illustrator.uservoice.com/forums/601447-illustrator-desktop-bugs/suggestions/47439314-pdf-fi...