Specify image save format in python script

Hello,

This question is not related to render image, but to texture image.

How can i specify save format for an image in a python script.

Is it possible to mimic the format of the save-as menu of uv/image editor.

If i create a new image, and save it, it seem to be tga.
If i load an image, is it possible to force save to tga format for example ?

Have a nice day
Ouille.