Photoshop drawing without background gets a strange grey line when exported as pdf from InDesign

[Kristel Hermans]

Hi, 

I've combined drawings from Photoshop in InDesign. Those drawings don't have a background in Photoshop (the white layer that I use as background is turned off), but a strange grey line appears around my drawing when I export from InDesign to pdf. I've attached two documents to this post to show you how it looks. That line isn't in my drawing when I look at my drawing in Photoshop with the white layer as a background turned on. Does anyone of you knows what's happening and how I can prevent this from happening?

Thank you in advance! 

Best regards, Kristel 

[Peter Spier]

It might be "stitching" which is a screen artifact caused by flattening transparency. It genrally does not show in hi-res prints.

What settings are you using for export?

[Scott Falkner]

What format is the image from Photoshop you are importing? Have you tried flattening or merging layers and saving a copy?

[Brad @ Roaring Mouse]

Turn off Smooth Images in Acrobat's Preferences for Page Display. It's adding an unncessary anti-aliasing to your image which is allowing the alpha mask to peek out at the edges at certain View percentages.

[Brad @ Roaring Mouse]

That being said, since your background is white anyway, why not flatten the entire image? That would eliminate the issue.

[rob day]

Hi @Kristel Hermans , when you export do you have Down Sampling turned on in the Export Compression tab? Your capture looks more like downsampling anti-aliasing than stitching from transparency flattening.

Does it happen if you Export to the PDF/X-4 preset with Downsamling turned off? Like this:

[rob day]

Also, the PDF you attatched has live transparency—it hasn’t been flattened—so it can’t be the stitching typically caused by flattening. The image resolution is 300ppi, so it looks like you are downsampling on Export?

The fringe pixels are in the file: