I'm a psp user, but I'm sure photoshop would let you do more. Anyways, just experimenting with a few color balancing tools I came up with the sample below. The only problem with this quick and dirty method is that you will loose your whites in the character sprites. Since alot of the sprites have a blue tint, the easiest thing would be to mask off the mainly white sprites and leave the slightly tinted ones alone(as in change the blue tint to green.