Imaging Engine output has gaps inside traps when low resolution is used, e.g. for Gravure or Proofing.
When Imaging for Gravure or Proofing, pixels are missing inside traps. These might be seen if the PDF was trapped using Esko PowerTrap, for example, as shown in the image below.
Solution / Workaround
The gaps arise because the curve of the trap does not quite mathematically match the curvature of the original object, and so a misalignment occurs when rendering.
The gaps can be obscured by enabling the Anti-Alias option for Imaging Engine. This does not make the gaps disappear completely, but it does make them very small (less than 1 output pixel in size), and so for all practical purposes they disappear. The output with Anti-Alias set to 4 is shown below: