Create maps with Gimp

[deepsky88]

Hi all,i want to create a single png image of like 800 x 20000 and set collisions inside Phaser, is there a way to set dinamic collisions? I succeded to put that file in my game but my ground is always the same, indipendently of the ground drawn in the png. I could use Tiled but i like doing some personal art style, any help will be appreciated, thx =)