Yes, it is very easy, they can even be animated with an MOV. File.
Create a design in illustrator or photoshop with transparency (make sure the bgd layer is off) and save the psd file or png. Then import it in your sphere’s material under alpha channel.
It’s that easy.
you can also use this same idea with an MOV file creating an animation in AE and rendering out an animation sequence with Alpha and RGB.