Allow Static Images as a Burn-In

[david-cattermole]

Users have requested the ability to display a logo, or image in the burn-in.

The position of the burn-in must be adjustable, like text, points and line. This will (likely) be a new "image" Field Type of some sort.

I do not expect an image sequence to be required, and only basic image formats such as JPEG and PNG would expected as input images. PNG would likely be the preferred image format since it supports transparency.

The current implementation of the burn-ins uses Maya Python API 2.0. Maya Python API 2.0 has the limitation that textures are not able to be used (in Maya 2018 at least). Therefore to support this feature we must port the entire node to Maya Python API 1.0.