Right now images fire
loadend when they are completely finished loading.
It might be interesting to have events that fire when progressive scans within the image complete.
(for more on progressive scans, see http://cloudinary.com/blog/progressive_jpegs_and_green_martians)
This might allow you to do things like adding Medium-style blurring or other effects to indicate clearly that images are not yet completely decoded, or for aesthetic reasons to cover artifacts.
It also might allow you to truncate loads when “enough” data from the image has been loaded on the client side, though I haven't thought this use case through yet.