Correction For Chinese Characters Formed By Simulated Irregular Phosphene Map

This paper focused on correction for Chinese character patterns formed by irregular phosphene map in simulated prosthetic vision, and systematically investigated how correction methods affect the Chinese character recognition performance.To reduce the unfavorable influence of phosphene array irregularity on the form of Chinese characters so as to improve recognition accuracy and time in visual prostheses, two correction methods were put forward. One method was to generate phosphene closest to the target point in regular arrays using weighted nearest neighbor search. The other was to generate phosphene in irregular phosphene array whose center located in the region covered by Chinese characters in a Song typeface without serifs dilated and eroded in different directions. Based on a simulation system, Chinese character recognition tests were given to twenty normally sighted subjects under five degrees of array irregularity (irregularity indices k are 0.2, 0.4, 0.6, 0.8 and 1.0 respectively) without correction. The recognition accuracy decreased with the increase of irregularity. When the recognition accuracy dropped below 80%, two correction methods were applied and their effects on improving Chinese character recognition accuracy and time were investigated. With the increase of array irregularity, their improvement on recognition accuracy and time grew considerably. Comparison between the two methods revealed that the former method afforded higher recognition accuracy and the latter was more appropriate for phosphene maps with serious irregularity than those with slight irregularity.