If you are trying resizing a picture for an avatar, chances are you won't be doing it on a regular basis. Therefor having the capability to do it isn't nearly as importiant as having it done. Just post (the biggest version) of what you've got and I'll just do it for you. How many pixels a 50kb image has is determined by how detailed the pixels in the image are. Simply bumping the ISO from 100 to 3200 determines whether I can squeeze 310 or 244 photographs of the highest quality (RAW) on a 4gig card for example. No mater how much ISO I decide to use, every picture has the same amount of pixels.