Large Format Document & PDF Downsampling Issue

[Chris_RoArk_]

Illustrator version: 29.8.1

Previously, when illustrator artboards/set of artboards went over a certain size, Illustrator would convert the document to a large format document and extend the canvas area to a new larger maxiumum.  When saving out PDFs, the size would be converted to 1/10th scale.  That has since been fixed with newer PDF versions.

However, I have a document that is a large format document with some raster images in it.  My adobe PDF preset is setup to downsample raster images 300dpi for anything over 450.  This usually works fine.  And I have not noticed this issue before.  But currently, the downsampling number I have of 300dpi is getting converted to 30dpi in the final PDF.  I have confirmed this in acrobat with a preflight check.  if I take the same document, and set the downsampling to 2400dpi, the output PDF is 240dpi.  So it seems to me that the downsampling number is getting the same 1/10th scaling treatment that was happening with the dimensions.

Here are my downsampling settings:

Here is the resolution of the image in illustrator:

Here is the effective resolution of the image in the final PDF:

If I take any image from this document, copy it over to a regular format illutrator document, and save it out with the same PDF preset with 300dpi downsampling, I get the correct DPI in the final pdf.  I have tried opening this with an older version of Illustrator 2024, but currently it's crashing on my machine when trying to save the PDF.

Is this a bug with the newer versions of Ilustrator?  This hasn't been an issue for me in the past, so it seems to be something new. 

Is anyone else experiencing this issue?

[creative explorer]

@Chris_RoArk_ when I work with images, I always resize the images to the exact size that is needed. So, if I am placing an image at 300ppi, and I decide I need to resize this smaller, I make a note of that size and go back into the Photoshop and downsize the image with Bicubic Sharpener on for Reduction algorithms. The reason why I do this is to make sure I have better control and my finished file is exactly at 300ppi versus letting the PDF application to do it for me. Peace of mind. And I have never had any issues with the commercial printers for this reason either. 

[Chris_RoArk_]

Thanks for the response.  That is a great way to do it.  In my case, I work at a commercial printer with a design and prepress team that handles of files/projects at once and it would just be a bit too time consuming to have to do that with every image we work with.

[creative explorer]

@Chris_RoArk_ oddly enough, I use to work at a Commercial Printer as a Pre-Press Technician, and that's how we were trained to create the files! 

[Abhishek Rao]

Hi @Chris_RoArk_,

Thanks for sharing the detailed explanation. Could you please confirm the OS version you’re working on as well? Also, let us know if the issue is happening only with this particular document or with all large-format documents on your end.

It would be very helpful if you could share a short screen recording showing your full export workflow, along with the check in Acrobat. If possible, please also share a sample file for us to test. If the file is confidential, you can share it via DM on the community using any public cloud service like Google Drive, Dropbox, or similar.

Looking forward to your update.

Abhishek

[Chris_RoArk_]

Hi Abhishek,

This is happening in all large format documents.  Fortunately we don't have a ton of these.  But we have enough of them that we have had a few reprints in the past weeks as we were getting ready for a convention build out.

Here are my system specs:

Here is the video saving out the PDF and doing a preflight check:

Screen Recording 2025-09-29 at 3.35.11 PM.mp4

Here's a link to the test file:

sample file for adobe.zip

As a side note, I've also noticed that the bleed settings in the acrobat also have 1/10th scaling applied.  See below.  My document is setup with .125" bleed.  But the PDF bleed settings show 1.25.  To be clear, that exact PDF profile is setup by default with .125 bleed settings and to ignore document bleed settings.

 

[Chris_RoArk_]

@Abhishek Rao Any updates from Adobe on this issue?  

I ended up creating a new specific PDF preset for large format documents and setting the downsample resolution to 10x the DPI that I was needing and that is a good work around so far.  But it would be nice if we didn't need to use a specific preset for just that scenario.

[Abhishek Rao]

Hi @Chris_RoArk_,

Thanks again for sharing all the details and the video. To dig a bit deeper, I'd need a sample file from you since my test file ran through without showing the same behavior. Could you please share a sample document where this happens? If the file is confidential, you can send it via DM on the community using any cloud sharing service like Google Drive, Dropbox, or similar.

This will help me run the test more accurately and share the findings with the team.

Looking forward to your update.

Abhishek

[Chris_RoArk_]

Hey Abhishek,

I shared a sample file in my post above.  Let me know if that link doesn't work for you.

[Ton Frederiks]

Here is another example, open the attached pdf in Illustrator and compare it with the result in Acrobat.

[Ton Frederiks]

@Chris_RoArk_ this is a problem with Large Canvas documents. You can turn off downsampling or enter resample to 3000 ppi which will turn into 2400 ppi and you will get 240 ppi.

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

[Chris_RoArk_]

Good point Ton.  I did try this as a work around and it's a possible solution.  But it feels more like a hack than an actual fix.  Hopefully Adobe will be able to address this issue so that the downsampling will behave as it should.  I don't mind creating another PDF preset for my large document format files.  It's more an issue of getting the rest of the team on board with when to use what preset as we already have a few presets we use for different things.  I try to keep the process as simple as possible.

[Ton Frederiks]

I think it is safer to work at scale and enlarge at print time. There are quite a few problems with large canvas document, this resampling is one example (you will get the same problem when you crop an image to 300 ppi in a large canvas document). 

[Bobby Henderson]

Adobe can try to fix things on their end. But another variable you have to watch is the large format RIP application handling the PDF on the other end. Not every RIP application is going to honor large canvas settings in a PDF. I find it safer to design the Illustrator artwork at a certain defined scale, such as 50% of actual size or 10% of actual size. When I bring the PDF files into the RIP application I'll scale the artwork up to full size there.

[Chris_RoArk_]

Good point. Our rips currently handle the large documents just fine.