Gray lines around imported images in Affinity Photo when exported to pdf

[Debatosh]

Please look into the matter. When I paste external images to Photo and then try exporting to PDF the PDF contains gray lines bordering those images. In one instance, I copied an excel table as a picture, rasterized it and then used auto contrast which removed the box around the text. But when exporting to PDF it shows those box lines. What I did was to first export it as a high res tiff and then print to pdf. However, the developers need to work on this issue as not everyone will like to export is to tiff and then convert to pdf especially for large size files or doing multiple files at once.

[Joachim_L]

Welcome to the forums @Debatosh. Could you please post a screenshot or a sample PDF? If this does not help, upload the Affinity document. 

[Pšenda]

8 hours ago, Debatosh said:

the PDF contains gray lines bordering those images

Yes, unfortunately it happens. In my opinion, this is due to inserting the image as an "Image" layer, not a "Pixel" layer, so just rasterize the layer before exporting. There may be a problem recalculating the inserted pixels to the new position.

[Bobolous]

I get the same thing. It's something to do with shadows, I think: because while most of the several reports on these forums about this issue talk about grey lines, on this image where the shadow should be brown, the lines are brown.

Sample from the PDF in Acrobat (as it should be):

Imported into Affinity Photo:

Note that while the original post here said this happened on export to PDF, this is what I see as soon as I import the PDF into Photo.

I can literally open the PDF in AP, the lines are there, and of course if I then re-export the image as a new PDF those artifact lines appear in the new PDF! Every PDF I've tried to open in Affinity Photo is showing issues like this?

Edited October 5, 2023 by Bobolous
just adding some clarity

[Dan C]

Welcome to the Affinity Forums @Bobolous & sorry to see you're having trouble!

Can you please provide a copy of the PDF file you are importing into Affinity here for me?

Many thanks in advance

[Bobolous]

Thanks I've DM'd you, @Dan C.

[Bobolous]

Just for the record, @Dan C and I chatted in DM. They were super helpful and tracked down more or less exactly what the issue is, but it's to do with how the shadow layers were exported by the original designers from InDesign to PDF, and at least this particular issue with the square "outline" artifacts can be seen when re-importing that PDF into lots of common graphics apps (not just Affinity Photo and Publisher).

In essence, graphics apps are importing a full coloured rectangular layer, then applying a mask to this object in order to display the shadow effect, however the Mask size is clipped to the size of the 'Group' that contains both the Rectangle object and Mask - which appears to be 1px smaller than the Rectangle itself, causing the thin lines we're seeing.

With permission I took Dan's findings and have emailed them to the original publisher. Maybe they'll reissue the digital downloads. Maybe they won't. But if your'e seeing a similar issue it might be caused by something like the above!