Gossip processes downloaded images. It has a setting for which image resize algorithm to use (Nearst, Triangle, CatmullRom, Gaussian, Lanczos3). This is to avoid gigantic images, and to make the images fit better. It also rounds avatar images.

The point of downloading the image in gossip is to show it. If people want originals, the URLs are there and clickable and you can open images in your browser (not for avatars though).