How Is the Iris Captured?

The iris is visible to the naked eye as a mosaic of texture. This is what is seen when the visible spectrum of light is used to illuminate the iris. When light from the near infrared regions is used, "slowly modulated stromal features are seen to dominate the iris." ^[2] It is these features that can be imaged up to one meter away with appropriate technology. The technology normally involves a monochromatic CCD camera in the 480 x 640 resolution range. This is used to extract an image frame of approximately 100 “140 pixels in radius to capture the iris sufficiently.

^[2] John Daugman, "How Iris Recognition Works," University of Cambridge, p. 2.

For a user to have his/her iris captured, he/she needs to look into a camera and receive feedback on whether to move the camera up, down, left, right, closer, or farther away. Once the camera is appropriately positioned, a frame is captured and the iris is localized.