16-Color Sprite Downsampling

I have around 300 PNG sprites for my 3-D ray-caster that still sit at the original 256-color depth. They include every animation frame for the enemies as well as the various pickups, so both sets must be handled and preserved exactly as they are now—just reduced to a clean 16-color indexed palette... (Budget: $250 - $750 AUD, Jobs: 3D Animation, After Effects, Animation, Game Asset Creation, Game Development, Graphic Design, Image Processing, Photoshop, Pixel Art, Sprite Design)