Iris Video acquisition
We developed a device for the acquisition of iris image sequences. The left eye receives visible light stimuli (white light) at computer-controlled specific time intervals, while the right eye image is captured and digitized into a video sequence under NIR illumination. The two sides of the device related to the left and right eye are optically isolated from each other.
The
video sequence obtained under NIR illumination is synchronized
with the “visible light” pulses (a white LED was
employed) applied to the other eye. Thus, it is possible to
extract the features of the frames during pupil contraction or
dilation without the interference of light reflections from the
iris, pupil and sclera. Their movements are induced by the light
stimulus applied to the other eye and, due to the consensual
reflex, repeated by the eye whose image is being digitized
without interference from visible light reflections.
The prototype was built with two multi-spectral cameras, digital and progressive scan model AD-080GE, GigE Vision compliant, belonging to the JAI C3 Advanced family. The AD-080GE employs 2 CCDs, one for BAYER color and the other for NIR monochrome utilizing prism optics so that the AD-080GE can inspect the objects by visible color sensor and near infrared sensor with the same angle of view. The AD-080GE provides a frame rate of 30 frames/second at full resolution of 1024 (h) x 768 (v) active pixels. Using a partial scan, the camera can achieve faster frame rates up to 85 fps. The 1/3" CCDs with 4.65 μm square pixels offers a superb image quality. The high-speed shutter function and asynchronous random trigger mode allow the camera to capture high quality images of fast moving objects.
This work was supported by the São Paulo Research Foundation (FAPESP), under grant #2011/18645-2.
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