thin lines appear around transparent objects in pdf

[ganeshagames]

I am creating a pdf for a book created in Designer Pro X9. I need to print it on Createspace (Amazon's print on demand system). I have tried exporting as a pdf with images at 300 dpi.
When objects are flattened by the PDF process, a thin line appears around objects with a transparent background.

The lines do not show up when I open the pdf with acrobat on my pc;
the lines do show if I read the pdf on my ipad;
the lines show on the pre-press pdf.

Is this a known problem and how can I avoid this? Thanks

[Albacore]

What zoom level did you use on iPad? Small lines can appear when the zoom level is over 150%. Before exporting flatten the area by making it a bitmap copy (Shift+Ctrls+C) if you think most people will read book at that zoom level.

[mwenz]

The print version. Do these thin white lines print? If not they are stitching artifacts from tiling.

Using Acrobat, zoom in progressively where there is a line. If the line remains pretty munch the identical thickness, they are stitching lines (and likely they will disappear at some zoom levels, reappear at others). They mean nothing as regards printing at that point.

[ganeshagames]

the book is 6x9 inches so I am not zooming on ipad. I think it is an artifact there as their appearance is not consistent (sometimes they show, sometimes they do not).
But on the proof PDF I got back from the printer -- they have become more visible. I have sent a copy to Xara.

[ganeshagames]

Yes they print, although not in a consistent manner. When they appear on screen, they print.
They are like 0.25 lines on the borders of many (but not all) transparent objects.

[mwenz]

I don't know what PDF settings you are trying.

Try using PDF 1.7 (Adobe Reader 8). Uncheck "Preserve Bitmap Tiling" on the Objects tab. No bitmap compression (same tab). I don't think the General tab options will affect anything. But you might want to turn off Optimize for fast web viewing.

If you want to ZIP up the XAR file, I would be happy to take a look. If so, upload it to dropbox.com or another place and PM me the link to it. If you use non-standard Windows fonts, be sure to include them in the ZIP as well.

[mwenz]

Oh, one more thing. If you have vector (elements or text) on or touching bitmaps, make sure all text is on a higher layer than the bitmaps and that nothing is grouped together.

[ganeshagames]

thanks I will send it to you in a minute. I have the xar file, all the fonts and a PDF proof generated by my printer. I think they use PDFx1 but in the past I have printed other PDFs (not generated by XDP) with no problems.

[ganeshagames]

I think I cannot send PMs?

[ganeshagames]

can you please drop me a mail at [email removed] and I'll email you a link to the zip file. thanks!