Abstract: The production characteristics and process characteristics of bumper painting are described,the differences in the gray values between the bumper substrate and the sprayed black primer under different exposure levels are compared,and the application effect of determining the spraying quality of black primer by gray value is verified by adjusting the ambient illumination and exposure experiment. The installation,debugging and improvement methods of automatic testing equipment are introduced,which provides theoretical reference and practical basis for automatic testing of primer spraying quality in painting industry in the future.

Key words: black substrate, black primer, ambient illumination, camera exposure value, gray value