That need to be processed in the photos? Sometimes you need to lighten or darken the desired image area.
Unsuccessful exposure shooting object. For example, it can "protruding from the head post", or arm or leg passers shown in the picture.
Unnecessary objects. This can be a bag in his hands, or just sitting in the wrong place at the bird. Unfortunate person. Lack of a smile or a sad face. All this can be corrected.