Abstract: Taking the Derwent Innovations Index database as the data source, selecting China, the United States, Japan, South Korea and Germany as the comparative research objects, this paper analyzes the overall trend of image understanding technology in the five countries by patent metrology, and adopts the technology competitiveness model to evaluate the technical competitiveness of the five countries. The results show that China is far ahead in the number of patent applications, but the average cited frequency of patents is far lower than those of the United States and Japan. At the same time, the United States almost occupies all the highly cited patents of image understanding technology. Owing to a large number of image understanding technology patents, China's technical strength is slightly ahead of the United States, becoming the first. However, the technology impact index of China is below the expected value, far lower than those of the United States and Japan. The results indicate that China possesses plenty of image understanding technologies which commonly lack of influence. Overall, Japan, South Korea and Germany fall behind China and the United States in terms of technical strength, but each has its own advantages in a certain sub technical field. Japan's technology impact index of scene recovery technology is far higher than those of China, South Korea and Germany. South Korea's image perception and interpretation technology patents account for a large proportion in the world; Germany's technology impact index and patent sharing index of spatiotemporal technology are at the top level in the world. To enhance China's international competitiveness in the field of image understanding technology, it is suggested that China should promote the in-depth development of image understanding technology, promote the balanced development of various sub technologies in the field of image understanding technology, strengthen international cooperation in the field of image understanding technology, and innovate the government service system, so as to create a good environment for technology development.

Key words: Image Understanding, Patentometrics, Comparative Study, Technical Competitiveness