Development of the Impaired Vision Aid

• Main Authors: Yi-Jhen Shie, 謝易振
• Other Authors: Yin Chang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/09966738574137244544

碩士 === 國立陽明大學 === 醫學工程研究所 === 95 === Objective：A special designed vision and system for low vision subjects has characters with technique of image enhancement so that it can improve the subject’s visual acuity without much magnification. Method：The differences of causing low vision between subjects are relatively large. Thus it is needed to give evaluation of visual function for the low vision subjects prior to carring out the image enhancement. Test of contrast sensitivity function (CSF) is carried out in subjects and the results are compared with the normals. Visual degradation transfer function (VDTF) is calculated for each subject according to the normals so that the visual deficiency in spatial frequency of the low vision subject can be defined. About 15 frame/sec enhanced images can be output through the image enhanced process by using TMS320 DM642 (720MHz) digital signal processor. CSFs of a total 31 normal subjects (age=26.2±5.4 years) with corrected visual acuity equal or better than 1.0 and a total of 11 low vision subjects (age=46.5±30.4 years) due to various causing of diseases are collected. Result：The results show that the uptake of image information without magnification has been increased 2.5 times on average after image enhancement for the low vision subjects; also, the reading speed increase 1.5 folds too. Conclusion：This research provided a method of image processing to replace traditional ways of magnification for low vision peoples so that they can have adequate aids for their adily use. At present, this aids can be used for reading or learning for characters.