I GOTS ONE WORD FOR YAS---- GIMP!!!!
ok... sorry about that... but i am a big advocate for the little (and free) people... umm well as photoshop and adobe are fine for what your trying to accomplish.. gimp is cross compatable with linux windows possibly mac i havent checked and it can handle pretty much any format you throw at it... if you need it to it can work like photoshop or adobe and it can do more the windows might be a little tricky at first to figure out but once you have it down its real easy to use and
ITS FREE! because its open source
to save my self from going on a rant and using up the last of my class time and to save you from a bunch of unnessisary boredom lets just say open source is a bunch of programmers getting to gether and saying hey i like this program but i wish it could do this... and making a program they made themselves that does "this" and putting it up on the web so other programmers can say hey! i like your idea but what if the program could do this too? and adding their own stuff in
and the result of it is an opensource program which you the user can then download on your computer and use with ease for free
if your interested go ahead and google it...
^^
sorry about my tangent... just trying to inform the world that not every thing is owned by a corperation ^^ *hugs*