This program gives an image a frame, padding it out to a specified aspect ratio, center & colour. The defaults are an instagram friendly aspect ratio of 1080 * 1350 and a black background. Colour can be changed by passing a value to add_padding.
Use the aspectpad_runner automator app to launch the python file. This is what you set the C1 process recipe to open the file in.
[your path] can be found by dragging this python file onto a terminal window and copy-pasting the output. Don't forget to remove the [] surrounding [your path]!