Usage its like ofxThreadedImageLoader, but if you add:
ofAddListener(ImageLoaderEvent().events,this,&YourClassName::YourCallback);
You get an event knowing if the image its loaded ok or not, and why.
void YourClassName::YourCallback(ImageLoaderEvent &_e) {
// _e.loaded (true,false)
// _e.error_msg (string)
}