LOCKED: why white lines on pdf

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https://community.adobe.com/t5/indesign-discussions/why-white-lines-on-pdf/td-p/8823035

I have an additional complication on this subject.

Workflow example:

1) Export single page PDF/X-1a of a brochure cover from InDesign

2) Rasterize the PDF in Photoshop

3) Flatten and save cover as PSD and JPG formats for other uses

4) Place the PDF of the cover as a link in new InDesign layouts

5) Export PDF/X-1a of new layouts for printers

 (I know it's an outdated standard and I've tried to get around it, but a lot of printers are still insistent on PDF/X-1a)

My mac was peviously running Catalina OS, using InDesign 2021. I was able to export PDFs using the workflow above and never had any issues with the white lines.

Since updating to Monterey OS, the white lines have returned with a vengeance. I have tried using Indesign 2022 and PDF/X-4, but the white lines continue to be an issue (unless you turn off Smooth Images in Acrobat). But since that is only a page display setting, the white line artifact is still present in the PDF (even though it won't actually print). Becuase of this, I can no longer rasterize a PDF in Photoshop beacuse the white line carries through. It also means I can no longer place those PDFs as links in other layouts. The white line carries through.

I am working around some of this limitation by exporting an EPS from InDesign and then rasterizing that to make the PSD and JPGs that I need. However, every PDF I export that has transparency shows the white lines. It's a big problem because we send PDFs to internal and external users all the time for reviwews and approvals. Explaining the "Smooth Images" setting in Acrobat over and over and over to new people is not efficient or sustainable.

Are there any known white line issues that are related to Monterey?

Sometimes the outputted PDF will be viewed electronically and not printed. So having thin, white artificact lines is unacceptable. 

Does the image file-type used make a difference?

My current situation is being on a tech writing team that's switching from Word to FrameMaker. 

Initial testing with FrameMaker shows that the outputted PDFs have thin white artifact lines on the images. 

These lines don't show up when PDFs are exported from Word. 

One factor is that callouts/text are being added to the images (using Illustraotr), and then the entire image (text and image) is being exported I think as an SVG. Maybe exporting both text and image "flattens" it and causes this artifcact issue. 

I'll do some testing to see if file type makes a difference, e.g. if bitmap works better than vector. 

It's very frustrating.  I also get these lines in my transparent boxes - I've learned to poke them around until the lines disappear and quickly print, but this is clearly a bug.  I keep expecting InDesign to fix this but it's always the same.  I am not talking about the usual ghost lines on a PDF export, this is not something that disappears on print. 

While the lines don't show in print, they DO appear in the online version of papers and magazines via Pressreader. It's really not a great look on ads you've paid for.

It bugs me that this continues to be a problem. Customers aren't interested in hearing "this doesn't show in print". And then you end up having to rebuild a file in photoshop to flatten it when you were using Indesign's dropshadow features and other features. It's really frustrating. Will there ever be a fix?

This issue is normally due to image flattening in combination with antialiasing and quite unavoidable. These lines aren't visible at print output. If you go to Acrobat's preferences and switch off "Page Display/ Smooth line art" and "Smooth images" the lines should disappear, if you look at your PDF in 100% size.