[Image-SIG] RGBA to P problem

[Nicolas Pinault]

Hi,

I have an application where I need to convert RGBA images(png) to P 
images (gif or png).
I use im.convert("P") to do the conversion. The problem comes with alpha 
channel. The resulting P mode image does not contain any tranparency 
information. Transparency is set to none and transparent pixels are set 
to black (in my test).
I tried to add an alpha channel after the conversion with 
im.putalpha(alpha). This converts the image back to RGBA mode.
Is there a smart way to do the convertion ?

Nicolas Pinault