If you like to use filters in photo apps, you've probably had that moment where the available filters weren't quite what you were looking for. Wouldn't it be nice if you could craft your own? Prisma thinks so. It's updating its service with an option to create your own styles -- specifically, you're training the machine learning system to generate what you want. It's not the same as making a filter in-app, but it could go a long way toward giving your photos a personal touch.