letterbox

Hi @tj, thank you for creating a convention tool to process photos. When I first to add option, it can't set bg as white in my photo, so I delete photo and re-run original command with option it can work, but the interesting thing is: I deleted photo and re-run command with removed option and keep option, it still can set photo bg as white. I feel something confuse. In my mind, when I created a processed picture and running the command without , I think it can't change photos.