  In contrast to batch learning where all training data is available at once,
continual learning represents a family of methods that accumulate knowledge and
learn continuously with data available in sequential order. Similar to the
human learning process with the ability of learning, fusing, and accumulating
new knowledge coming at different time steps, continual learning is considered
to have high practical significance. Hence, continual learning has been studied
in various artificial intelligence tasks. In this paper, we present a
comprehensive review of the recent progress of continual learning in computer
vision. In particular, the works are grouped by their representative
techniques, including regularization, knowledge distillation, memory,
generative replay, parameter isolation, and a combination of the above
techniques. For each category of these techniques, both its characteristics and
applications in computer vision are presented. At the end of this overview,
several subareas, where continuous knowledge accumulation is potentially
helpful while continual learning has not been well studied, are discussed.
