I recently encountered a weird problem with the Inner Shadow effect in InDesign. It took a bit of digging to figure out how to fix it.
Graphic frames with an Inner Shadow looked fine in InDesign, even with Overprint Preview on. The outcome was fine if the file was exported with PDF/X-4 or any other PDF preset using Acrobat 5 or later compatibility. However, the printer had insisted that the client use a supplied PDF preset based on the PDF/X-3 spec, which flattens transparency.
In Acrobat, the PDF looked fine with Simulate Overprint checked. But when Overprint was unchecked, the images disappeared, leaving white rectangles. The PDF would not print correctly unless overprint was turned on in the printer’s workflow; for various reasons, the printer preferred to not turn on Overprint.
Interestingly, the problem occurred only if the image frames were on a spot color background, even though there was no apparent interaction between the image frames and the background.
Here’s how I fixed it:
- Removed the Inner Shadow effect on the image frames.
- Changed the image frames’ fill to [Paper] (it wouldn’t work if the fill was None).
- Duplicated the frames to another layer and deleted the images.
- Changed the duplicate frames’ fill to [Paper], added the Inner Shadow, and set the frames to Multiply (without a fill, no shadow could be created).