Icons checked in with faulty transparency settings

Hi!

A couple of images just got checked in (icons for image and table, iirc 
by Donovan), and it looks like they don't have transparency properly 
set, since they get little borders when used against a background that 
is not gray. Also they are somewhat inconsistent with the rest (although 
I don't mind that so much, perhaps we should even make the rest 
inconsistent with those new ones?)...

What do you guys think we should do? Remove the new ones again? Fix 
transparency and leave it like it is? Change the rest too?

Cheers,

Guido