Final Fantasy Hacktics

Whenever I export a BMP from Shishi and go to edit it the portrait's colors are always inversed. Why? And how can I fix it so that I can edit it?

Use palette editor to fix this: http://ffhacktics.com/smf/index.php?topic=3901.0

Thanks man. That really helped a lot. But now I have another question.

Now I know it must be possible to insert new colors into a BMP. I'm editing Ramza's chapter 4 sprite and there's an apparent lack of color. I was using palette editor yesterday and noticed the palette colors. Most of them are black, so I tried to edit one to a red, but then it just highlighted everything on the sprite red. Help?