How to change the alpha color of a sprite?

Unity Engine
1

Hi there, I got some images (castle platformer | OpenGameArt.org) which I’m codding a game just for learn.
The problem is that the images have a different background color and I don’t find where I can change the default transparency color on Unity.

Is it possible? Can I change the default transparency color on a specific project/sprite?

Thanks a lot and sorry for the bad english.

2

You probably mean color-keys. Unity sprites don’t support that in 4.3. You will have to provide textures with an alpha channel.

3

Oh ok =[
Thanks very much.