New Post: Question about composite command and images of different sizes

Thanks for the reply dlemstra.
I've tried your suggestion, and I'm no longer getting black borders, however, now the entire image is white(though the watemark is visible). It appears that the transparency is lost once the Extent command is applied to the watermark. Is there an alternative to Extent, or is there another command to keep the transparency after the Extent command?

Thanks again!