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Low vision is a visual impairment that affects people’s daily lives. Based on the statistics of the World Health Organization (WHO), the population of low-vision patients worldwide has reached around 165,000,000, and this population is still increasing.1,2
Much research has been performed to aid patients with low vision. One of the important research areas is image enhancement technology. Image enhancement can be used to help low-vision patients access high-quality images with digital devices.3–5 A significant amount of work has been done in this area. For example, a systematic contrast-enhancement method has been presented to improve the content visibility for low vision patients who have the symptoms of loss of fine details and lack of contrast.6 A strong edge enhancement method was developed for low-vision patients that gives images a better visual effect.7 Low-vision people have a reduced ability to see public safety signals and signs in visually challenging environments. In order to address these situations, applications such as enlarging the targets on the mobile displays of those visually impaired individuals were developed.8 Currently, the images obtained from different sources are color images; thus, ways to enhance color images for low-vision patients is another research topic. In Ref. 9, image enhancement technology for color images was investigated. Experimental results show that the proposed enhancement algorithm for color images was effective. In Ref. 10, an image enhancement algorithm based on wavelet transform was proposed. Experiments were performed involving both a normal-vision person and a visually impaired person, each of whom provided feedback on their perception of the enhanced images obtained using the new algorithm. In Ref. 11, image enhancement technology was used to aid the visually impaired in face recognition. Besides the research mentioned above, many other reports deal with image enhancement for low-vision patients.
Mobile devices such as iPads or iPhones have become popular in daily life and thus can also serve as convenient tools for low-vision patients. Lowvision patients can use mobile devices to read text, watch videos/see images, navigate, etc. However, similar to the case with other electronic devices, the information needs to be processed before it can reach low-vision patients. For example, the text needs to be magnified before low-vision patients can read it, the images and videos need to be enhanced before the low-vision patients can view them.12 Text magnification is the subject of many papers, but not much research on image enhancement for mobile devices has been published. In this Chapter, we focus on image enhancement techniques for mobile devices.
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