title: Recognition of pixelized Chinese characters using simulated prosthetic vision.
abstract: The rehabilitation of the reading ability of the blind with a limited number of stimulating electrodes is regarded as one of the major functions of the envisioned visual prosthesis. This article systematically studied how many pixels of individual Chinese characters should be needed for correct and economic recognition by blind Chinese subjects. In this study, 40 normal-sighted subjects were tested on a self-developed platform HanziConvertor (Institute for Laser Medicine & Bio-photonics, Shanghai Jiaotong University, China) with digital imaging processing capacities to convert images of printed text into various pixelized patterns made up of discrete dots, and present them orderly on a computer screen. It was found that various complicated factors such as pixel number, character typeface, stroke number, etc., can obviously affect the recognition accuracy. It was also found that optimal recognition accuracy occurs at a specific size of binary pixel array, due to a trade-off between a strictly limited number of stimulation electrodes and character sampling resolution. The results showed that (i) recognition accuracy of pixelized characters is optimal with at least 12 x 12 binary pixels, and therefore it is recommended to apply a minimum of 150 discrete and functioning electrodes for restoring the reading ability of blind Chinese individuals in the visual prosthesis; (ii) fonts of Song Ti and Hei Ti are clearer and more effective than other typefaces; and (iii) characters with fewer strokes lead to better accuracy.
authors.affiliation: Department of Biomedical Engineering, Shanghai Jiaotong University, Shanghai, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Chai
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.forename: Changsi
authors.initials: C
authors.lastname: Cai
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Ren
mesh_terms: D044466:Asian People; D001766:Blindness / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual; D019736:Prostheses and Implants; D011601:Psychophysics; D011932:Reading; D012815:Signal Processing, Computer-Assisted; D014785:Vision, Ocular; D014792:Visual Acuity; D014796:Visual Perception