1:10 workflow with images and exporting as PDF

[graceful_magnificence5C22]

I have a layout which is 200 m x 2 m. I started in illustrator with a scale of 1:10, so 20 m x 0.2 m. The printing firm will print the layout on boards measuring 3 m x 2 m and wants a PDF with individual pages. So I splitted the layout in 67 artboards each 0.30 m x 0.2 m and exported them as PDF via "Save as copy".

My question: The layout contains images. The quality and placed size gives me about 720-1500 ppi for each image. How should I export to ensure that they remain their full quality after the printing firm scales it up x10 ? Is it enough to change all settings to "Do Not Downsample." in the compression tab?

[Ton Frederiks]

I would certainly not downsample the images. 720-1500 ppi will end up as 72 an 150 ppi after scaling.

Using these resolutions will probably be sufficient when viewed at a distance, which is almost certainly the case with a 200 meter wide object. Did you contact your printer about this?

[graceful_magnificence5C22]

Yes, I contacted my printer. 150dpi should be fine. I definitely don't want to downsample. I just want to preserve the quality. I discovered that illustrator also has a print option to export to pdf (conveniently in the final size of 3x2m) and also here I can exactly say how many dpi I want to export. Would that be the most viable way to export the layout?

[Ton Frederiks]

Windows? I would use the Illustrator save as way to create the PDF.

Print to PDF sounds like the old way to create a PostScript file that gets converted or a non Adobe way to create the pdf. But I am not on Windows so I do not have recent experience with that print workflow.

[jonathank92299298]

Yes, Windows. When I export it via "save as" to create the PDF, I need to know what kind of settings I have to have in the compression tab. When I select "Do not downsample" it seems that the images remain in full quality, BUT the file sizes are like 20 gb and it takes an eternity to export. Also when I use dpi numbers that are way bigger than what I have (which should also result in no downsampling imho – image below) illustrator nonetheless makes some kind of weird stuff and the images are pixelated.

And the weirdest problem I have is (also image below; the word which is barely visible is "Field"), that in the exported PDF some paths are still visible though they are masked. Which PDF (X1,X2,X3,X4) should I choose in order to get rid of those?

[graceful_magnificence5C22]

And the downside of exporting it via the "print" option in Illustrator is, that I can't export in X4 which leaves me with the problem of the artifacts because of transparency.

[Ton Frederiks]

Regarding reducing the file size. Unchecking the Preserve Illustrator Editing Capabilities will make it smaller (only do this when saving a copy, always keep the original Illustrator file). Jpeg compression set to Medium Quality should help too.

The lines you see are caused by transparency flattening and won't happen when you save as PDF/X-4.2010 or use the Illustrator default. But check with your printer which PDF version they prefer.

[jdanek]

If you are setting DPI in the PDF, then you have to know what the output resolution is in the RIP ( based on the output device which typically would be inkjet-grand format ).  But, you should not have to pre-set the DPI in the PDF with the way your files have been prepared.  Incedentally, grand format inkjet resolution is 600dpi, some are 720dpi and others are 1200dpi ( depending on printer ). You could save the PDFs as medium or office versions and feel confident the image quality will hold up.

[graceful_magnificence5C22]

My printer says they are printing in 1080x360 dpi. So when I do not have to pre-set the DPI, how do I ensure, that Illustrator doesn't downsample my images and preserve their quality?