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18 June 1999 Pupil meter and tracking system based in a fast image processing algorithm
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Proceedings Volume 3591, Ophthalmic Technologies IX; (1999)
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States
A low cost pupil-meter and tracking apparatus was developed. It is based in digital analysis of images of the anterior eye to measure the diameter of the eye pupil and to track the position of its geometrical center at video rate. The system consists in an array of infrared LEDs to illuminate the eye and a CCD video camera that captures the images of the pupil to be grabbed in a computer. A fast algorithm analyses the digital images (512x512 pixels) in real time (25 images per second) providing the pupil diameter and the location of the geometrical center within that temporal rate. The algorithm was implemented to run under DOS, Win 3.x or Win95 and is compatible with any frame-grabber. the reliability of the apparatus was tested in different subjects for the particular problems of measuring the pupil diameter during accommodation and tracking the eye position during fixation. Under the measuring range, the system is robust to moderate lateral and axial movements of the subject. The spatial resolution is 0.02 mm and the linearity in measuring the pupil diameter is better than 1% in the complete useful range. The apparatus was adapted to operate without interfering either the visual task or possible simultaneous measurements.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ignacio Miro, Norberto Lopez-Gil, and Pablo Artal "Pupil meter and tracking system based in a fast image processing algorithm", Proc. SPIE 3591, Ophthalmic Technologies IX, (18 June 1999);

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