Make a continuous map cut out?
I'm working an an equi-rectangular projection of an overworld map. I'm using Photoshop CS6. I'm just wondering how to make the map edges line up so that if I make a different projection of it using whatever program, there isn't a line of inconsistency where the left and right edges of the map meet. I think this also affects the top and bottom as well. Is there any simple way to make sure that the two edges line up properly and seamlessly? Or do I need to iron out the inconsistencies by hand?