This is an annoying trait of the InDesign 'Overlay Creator' when developing .folio content.

In this instance I was using the 'Image Sequence' plug-in. My original animation was a full screen interactive element which, in turn, disabled the users ability to swipe left/right to navigate through the page content. I therefore decided to set the background image to full screen, but reduce the interactive area, in order to retain usability and the swipe functionality.

As you can see from the screen grab below the interactive area is output in a darker tone to the remainder of the page content, therefore creating an undesirable page view. It is unfortunate and frustrating as you would expect a seamless merge between foreground and background.

Interactive content and background image colour difference

 
There is a way to rectifying this issue by masking out all image content that is duplicated in the background view, however, this is quite time-consuming and clearly the image shouldn't be rendered with different output colour values.

Whether this is a anomaly in the output process, or not, it adds an extra boundary/consideration to creating aesthetically pleasing interactive animations.