Processing usually starts with some image processing, where noise and distortion are reduced and certain important aspects of the imagery are emphasized. Typically, these events are blobs, edges, lines, corners, regions, etc. They are stored at the intermediate level of abstraction. Such descriptions are free of domain information - they are not specifically objects or entities of the domain of understanding, but they contain spatial and other information. Various techniques are used to interpret.
Most research is focused on the intermediate and high levels of abstraction.
There are researchers who take clues from biological systems to develop theories, and there are those who focus on mathematical theories and physics regarding the imaging process. Eventually however, theory becomes practice in the specification of an algorithm - embodied in an executable program with appropriate data representations. There are alternate views of vision, resulting in other paradigms for understanding and research. The author of this narrative cannot contrast and compare different approaches to vision in a meaningful and unbiased way. Instead, the reader is invited to investigate and learn, and hopefully contribute to this new science.