Similar to the impact of ageing on human beings, digital image sensors develop ageing effects over time. Since these imager’s ageing effects (commonly denoted as pixel defects) leave marks in the captured images, it is not clear whether this affects the accuracy of iris recognition systems. This paper proposes a method to investigate the influence of sensor ageing on iris recognition by simulative ageing of an iris test database. A pixel model is introduced and an ageing algorithm is discussed to create the test database. To establish practical relevance, the simulation parameters are estimated from the observed ageing effects of a real iris scanner over the timespan of 4 years.

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Impact of sensor ageing on iris recognition

Measurement and analysis of defect development in digital imagers

The infrared temperature measurement technique has been applied in various fields with the development of charge coupled device. In the problem of metal surface temperature measurement, if the surface is covered by participating media, the traditional infrared temperature measurement technique will lead to intolerable measurement errors. In this work, the infrared temperature measurement problem was solved by the source multi-flux method. On this base, the impact of the flue gas thickness and surface temperature on the apparent temperature measured by the charge coupled device was analyzed. Furthermore, the corresponding experimental system was set up. And the experimental results were found to have a good agreement with the simulated results. Finally, the idea of modification for the infrared temperature measurement by inverse method was proposed.

/pdf/analysis-of-infrared-temperature-measurement-for-flue-gas-30c148y02m.pdf

Analysis of infrared temperature measurement for flue gas shielding metal surface using Source Multi-Flux method

The present invention relates to an image pickup device relates to, dynamic range (Dynamic Range) for expanding the image pick-up operation and stopped the display deterioration caused by the contrast (明暗) of the subject with improved resolution of the solid image sensor element. A solid-state imaging device of the present invention as described above are formed on the light-receiving unit for receiving an image by light having a glass surface, the glass surface is selectively coloring or bleaching according to the brightness of the image by the light adjusting the quantity of the projected light adjusting the quantity of the projected light (投 光 量) to configure the photochromic mikcheung as to control the quantity of the projected light by the aperture at the time of implementation of the camera system according to the brightness by the photochromic mikcheung that the coloring and discoloring, which it is possible to simplify the system have. And the dynamic range of the solid-state imaging element is efficiently scale is effective to increase the resolution of the imaging device.

Solid state image pick-up device

As solid-state image sensors become ubiquitous in sensing, control and photography products, their long-term reliability becomes paramount. This thesis experimentally examines the nature of in-field faults and demonstrates two combined hardware-software approaches for detecting and mitigating them. Characterization experiments found that most tested commercial cameras developed hot pixels that create image bright spots and degrade dynamic range. Faults appear spatially point-like and uniformly distributed, and they develop continually over time. Silicon displacement damage, induced by terrestrial cosmic rays, is the likely cause. A fault tolerant active pixel sensor is developed to isolate hot defects to a portion of the pixel, enabling software algorithms to correct the faults without sacrificing dynamic range. Experimentally-emulated hot pixels can be corrected within ±5% error. A new statistical software approach is developed to identify and calibrate stuck and abnonnal-sensitivity faults from only regular photographs. Monte Carlo simulations verify the detection accuracy in complex environments.

Jozsef Dudas

Papers

Characterization and avoidance of in-field defects in solid-state image sensors