Camera characterization for face recognition under active near-infrared illumination

Active near-infrared illumination may be used in a face recognition system to achieve invariance to changes of the visible illumination. Another benefit of active near-infrared illumination is the bright pupil effect which can be used to assist eye detection. But long time exposure to near-infrared radiation is hazardous to the eyes. The level of illumination is therefore limited by potentially harmful effects to the eyes. Image sensors for face recognition under active near-infrared illumination have therefore to be carefully selected to provide optimal image quality in the desired field of application. A model of the active illumination source is introduced. Safety issues with regard to near-infrared illumination are addressed using this model and a radiometric analysis. From the illumination model requirements on suitable imaging sensors are formulated. Standard image quality metrics are used to assess the imaging device performance under application typical conditions. The characterization of image quality is based on measurements of the Opto-Electronic Conversion Function, Modulation Transfer Function and noise. A methodology to select an image sensor for the desired field of application is given. Two cameras with low-cost image sensors are characterized using the key parameters that influence the image quality for face recognition. © 2010 SPIE-IS&T.

Subjects

Active illumination

Camera characterization

Face recognition

Infrared imaging

DDC Class

004: Informatik

Funding Organisations

Bundesministerium für Wirtschaft und Technologie

More Funding Information

This work is part of the project KabTec – Modulares integriertes Sicherheitssystem funded by the German Federal Ministry of Economics and Technology.

Options

Camera characterization for face recognition under active near-infrared illumination