Generic and customised digital image enhancement filters for the visually impaired

• Published in: Vision research (Oxford) Vol. 45; no. 15; pp. 1991 - 2007
• Main Authors: Leat, Susan J., Omoruyi, Gloria, Kennedy, Andrew, Jernigan, Ed
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2005; Elsevier Science
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; Contrast sensitivity; Data Display; Digital image processing; Fundamental and applied biological sciences. Psychology; Humans; Image enhancement; Image Enhancement - methods; Low vision; Macular Degeneration - complications; Macular Degeneration - physiopathology; Macular Degeneration - rehabilitation; Middle Aged; Perception; Perceptual Masking; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Sensory Thresholds; Vision; Vision, Low - etiology; Vision, Low - physiopathology; Vision, Low - rehabilitation; Visual Acuity; Visual Fields; Visual impairment; Low vision; Visual impairment; Contrast sensitivity; Image enhancement; Digital image processing; Human; Vision disorder; Color; Digital processing; Digital image; Sensitivity; Vision; Perception; Masking
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2005.01.028

This study compares the effectiveness of various image enhancement filters for improving the perceived visibility of coloured digital natural images for people with visual impairment. Generic filters were compared with Peli’s adaptive enhancement and adaptive thresholding and custom-devised filters based on each subject’s contrast sensitivity loss. Subjects with low vision made within filter rankings followed by between filter ratings. In general, subjects preferred filters with lower gains. Unsharp masking resulted in a significant increase in perceived visibility for some image types ( p ⩽ 0.05) while Peli’s adaptive enhancement, edge enhancement and histogram equalization resulted in borderline improvements. Adaptive thresholding and the custom devised filter did not result in overall improvements in perceived visibility.