Does everything inthe document show properly when you switch to Overprint Preview in ID?
yes, on the preview screen I see everything correctly.
Waht happens if you change the export settings from PDF/X-1a to None in the Standards dropdown and check the Simulate Overprint box in the Output tab, or change to PDF/X-4?
Are there any effects applied to this background image?
The problem occurs when I'm in the export settings choose the smallest output file.
Once I "PDF / X. ..." select them, the images are accurately reproduced. However, the white border is always visible in the PDF. Only in the expression is the white border does not exist.
My print shop told me that it would involve a PDF representation problem. However, I can not explain why the images at the smallest output file exist?
The background image will be displayed with an opacity of 80%. The overlying images are all slightly twisted and all have a simple feather.
You absolutely don't want to use the smallest file size preset for printing.
I would recommend either the Press Quality (which converts colors to CMYK), the High Quality Print (which does not convert colors, but does not embed profiles) or best of all, if the printer can handle it, PDF/X-4 which leaves colors unchanged and embeds the profiles for conversion in the Printer's RIP.
My suspicion is the white lines you mention are a transparency flattening artifact known as "stitching." Using Acrobat 5 or higher compatibilty, which all of the presets mentioned above do, will leave the transparency live in the PDF for falttening in the RIP. I would not use the PDF/X-1a standard unless the printer tells you that he cannot work with live transparency. Stitching is usually only a problem on screen or in digital prints and generally does not show in press output.