Light intensity automatic adjustment technology and its application in palmprint recognition system

Palmprint acquisition device with constant light intensity is easily influenced by the ambient light. The phenomenon that the captured palmprint images are too bright or dark happens frequently, and it leads to the failure of key points location. In order to ensure the captured palmprint image can obtain a good quality, an automatic light intensity adjustment system based on PWM Control Technology is designed. It can make proper adjustments for the light source according to quality evaluation results of the current image. In our study, a new palmprint dataset was established under different light intensity levels. Then, an optimal mean gray interval is learned from the dataset. Finally, the automatic light control module is designed to guarantee the brightness of the captured image falls into the optimal interval. Experimental results show that the technology is efficient for palmprint key points location and ROI (Region of Interest) segmentation, and it also commendably improves the palmprint recognition accuracy at the same time.