This is from Gus Mueller, who writes my favorite image editor for macOS, Acorn (https://flyingmeat.com/acorn/). I've reported a bug to Gus and received a new build with a fix within minutes. I highly recommend his software, even his pizza-themed blog http://maybepizza.com/ which includes a nerdy pizza dough recipe generator.

I wonder if Retrobatch could have been made as a series of Automator plugins, allowing integration with more complicated workflows (e.g., upload the processed images or put them in a specific Photos app album or something).