I can do most things in Photoshop and creating the collage is not a problem, however canvas size and resolution are a complete mystery to me.
I am wanting to create a picture collage to be used on wall paper. The area it will eventually cover is roughly 3m x 3m (that's meters for you US people ;))
I am told I need an eventual dpi of 300. Is there a standard workflow for this? Surely I don't create a 3mx 3m canvas?