PDF files made on large artboards get downscaled incorrectly.
When exporting a PDF from a document that's set to "large artboard" the resolution of linked images will get downsampled 10x as much.
In the screenshots I've provided an example of an Illustrator document that's set to large artboard mode. Artboard is an A4 format with an image that's 300 DPI.
I then export the PDF saying it should downsample images to 300 DPI.
Once I open up the PDF in an InDesign document of the same size, you'll see the linked file appears 10x smaller. Not only that, but if you look closely at the image, you'll see that it became really pixelated due to it being effectively 30 DPI instead of 300 now.
I propose that the downsampling feature should take large artboards into account, and make sure that images remain 300 DPI after the PDF export.
Robin Mosterd
shared this idea
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Anonymous commented
So here's some advise:
Only use large canvas when absolutely necessary
Don't use 300 DPI for anything larger than ~36" x 48", as beyond that your are generally outside of the realm of Offset Printing. (Offset printing is the only reason why anyone ever started using 300 DPI as a resolution standard) Rather, use 100 to 150 DPI for larger images.
You can spoof the illustrator export into exporting a 300 DPI PDF when exporting from a large artboard by specifying that it export a 3000 DPI pdf. You will get a 300 DPI PDF in the end.
This is definitely an annoying bug, but the 10x work around totally works.
Keep an eye out for Document Raster effects also being affected by this bug.
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Ton commented
The idea behind large canvas is that you can create at large artboard sizes without using a scale factor.
There is only a warning triangle when you create a large document that exceeds the default canvas size limit. You cannot turn it off once created :-(
see https://helpx.adobe.com/illustrator/using/large-sized-artwork.html -
Keith Barnes
commented
OK, another comment and question. Where is the set up to "large artboard"? I've never heard of such a thing. I set artboard sizes as needed, but have never seen a box to tick that sets it as a "large artboard". Question can we deselect "large artboard"? Rhetorical question, what is the value of "large artboard" , I mean, setting the compression level of a pdf is simple.
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Large Canvas documents resample images 10x more than requested.
A 512 ppi image is cropped with a 300 ppi resolution. The resolution shows as 5120 ppi. After entering 300 and hitting Apply, the resolution becomes 30 ppi.
Saving a PDF with compression, Bicubic Downsampling to 300 ppi reduce the resolution to 30 ppi.
You cannot resample to 300 ppi, when you enter 3000 ppi instead of 300, you get 2400, which results in 240 ppi.
See attached PDF file with AI compatibility
