Coaxial optical structure for iris recognition from a distance

Abstract

Supporting an unconstrained user interface is an important issue in iris recognition. Various methods try to remove the constraint of the iris being placed close to the camera, including portal-based and pan-tiltzoom (PTZ)-based solutions. Generally speaking, a PTZ-based system has two cameras: one scene camera and one iris camera. The scene camera detects the eye's location and passes this information to the iris camera. The iris camera captures a high-resolution image of the person's iris. Existing PTZ-based systems are divided into separate types and parallel types, according to how the scene camera and iris camera combine. This paper proposes a novel PTZ-based iris recognition system, in which the iris camera and the scene camera are combined in a coaxial optical structure. The two cameras are placed together orthogonally and a cold mirror is inserted between them, such that the optical axes of the two cameras become coincident. Due to the coaxial optical structure, the proposed system does not need the optical axis displacement-related compensation required in parallel-type systems. Experimental results show that the coaxial type can acquire an iris image more quickly and accurately than a parallel type when the stand-off distance is between 1.0 and 1.5 m. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Auto-focusing method for remote gaze tracking camera

“…As shown in Fig. (12) and (13), respectively. (9) can be calculated for the current image, z x is calculated using Eq.…”

“…The focus score of the captured eye image is calculated in step (6). To focus more accurately, the optimal parameters based on the face width are saved in step (12). (This procedure is explained in detail in Sec.…”

“…Numerous studies have examined characteristics of the human eye, such as research on gaze detection, 1-7 iris recognition, [8][9][10][11][12] and the measurement of eye fatigue. Numerous studies have examined characteristics of the human eye, such as research on gaze detection, 1-7 iris recognition, [8][9][10][11][12] and the measurement of eye fatigue.…”

“…4. [1][2][3]8,12,17 Previous auto-focus control methods are divided into three types: active focus control, passive focus control, and hybrid types. On the other hand, if an eye image acquisition system uses an auto-focusing mechanism, it can capture well-focused images over a wider range of Z distance.…”

“…2,3,8,12,17,19,20 On the basis of this information, the system focuses by moving the focus lens back and forth. 2,3,8,12,17,19,20 On the basis of this information, the system focuses by moving the focus lens back and forth.…”