I've read this whole thread and have come to a conclusion about the problem with the starting images between BB and Cath.

BB is starting with a 'regular' photograph or image whereas Cath is starting with an image of a mirrored reflection which has to be flipped horizontally. If you take a picture of a mirror of course you have to flip it to get a 'regular' image. You both are right in what you are doing; the problem is with the starting image!