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A. Martin-Gonzalez, I. Lanzl, K. Kotliar, N. Navab; Real-Time Hybrid Magnification System for AMD Patients. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4732.
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To investigate the feasibility of implementing a real-time hybrid magnification approach in a head-mounted display (HMD) as a vision enhancement device for patients with age-related macular degeneration (AMD) based on graphics hardware direct access for faster computation.
An HMD (1280x1024 pixels, 60Hz) and two color cameras for stereo vision (1024x768 pixels, 30Hz) are used. The hybrid magnification consists of a radial linear magnification surrounded by a constrained radial non-linear magnification containing a smooth interpolation of hidden non-magnified information lying below the magnified area. This is programmed with the innovative OpenGL Shading Language (GLSL) for graphics hardware access. The system is tested on normal sighted people for reading and following route maps. The computation time for one video frame of a color camera (640x480 pixels, 30Hz) is compared with a version developed with OpenCV libraries without graphics hardware access.
The GLSL version is significantly faster (1.35ms per frame) than the OpenCV one (45ms per frame) and faster enough to process, in real-time, every video frame (acquired every 33.33ms) in contrast to the OpenCV one. Users performed assigned tasks with stereo vision, undistorted central zooming (due to linear magnification), continuity between magnified and non-magnified areas plus no-hidden information (due to non-linear magnification), and global context (due to constrained domain). The figure shows a classic linear magnification (left) and our approach (right). The magnification parameters are individually adaptable to every patient.
A head-mounted display based real-time hybrid magnification system was developed for AMD patients’ vision enhancement due to graphics hardware direct access. The system provides orientation within a complex environment. The system’s efficiency will be evaluated with AMD and low vision patients.
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