To generate PNG output files that places text and images onto a transparent background, simply upload a transparent piece of artwork (image file in PNG format) to the Products Print Area > Artwork slot. This tells the system to retain a transparent background when it produces final PNG output files. This field will be enabled by default whenever a Print Area is made as show below.
Important Note: The uploaded file should match the specified Print Dimensions at the relevant dpi and must be PNG format.
The Artwork upload slot can be found here:
The system generated artwork can then be tested via the Print Test facility to ensure it is suitable for production.