An assessment of the video image quality required in a remote vision guidance system for visually impaired pedestrians.
A study was carried out to determine the most acceptable quality of video images for use in remote guidance of visually impaired pedestrians. A video image clip of 20 s duration was captured using a digital camera, while walking a sample route. The video image clip was encoded at bit rates of 30 and 48 kbit/s, and frame rates of 10, 7.5, 5 and 2.7 fps. Two standard resolutions were used: Quarter Common Intermediate Format (QCIF) (176 x 144 pixels) and Common Intermediate Format (CIF) (352 x 288 pixels). Twelve participants gave their judgment on the picture update rate (smoothness of movement), the bit rate and the static resolution. The mean scores for total quality (five-point scale) ranged from 3.3 to 4.8, but there was no significant difference between them. The mean scores for smoothness (five-point scale) ranged from 3.0 to 4.7, but there was no significant difference between them. The mean score for the resolution of the QCIF video clips was 2.9 (SD = 0.9) and for the CIF recordings were 4.1 (SD = 0.7), but there was no significant difference between them. The majority of the participants were most comfortable with video which was transmitted at 48 kbit/s and 7.5 fps. Therefore, this quality can be considered satisfactory for remote guidance.
Hunaiti
Z
Z
School of Engineering and Design, Brunel University, Uxbridge, UK. ziad.hunaiti@brunel.ac.uk
Garaj
V
V
Balachandran
W
W
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D017060:Patient Satisfaction / Q000706:statistics & numerical data; D011786:Quality Control; D013813:Therapy, Computer-Assisted / Q000592:standards*; D014743:Videotape Recording / Q000592:standards*; D014786:Vision Disorders / Q000534:rehabilitation*; D016138:Walking