Most of today's video and digital cameras use CCD image sensors, where the electric charge collected by the photodetector array during exposure time is serially shifted out of the sensor chip resulting in slow readout speed and high power consumption. Recently developed CMOS image sensors, by comparison, are read out non-destructively and in a manner similar to a digital memory and can thus be operated at very high frame rates. A CMOS image sensor can also be integrated with other camera functions on the same chip ultimately leading to a single-chip digital camera with very compact size, low power consumption and additional functionality. CMOS image sensors, however, generally su#er from lower dynamic range than CCDs due to their high read noise and non-uniformity. Moreover, as sensor design follows CMOS technology scaling, well capacity will continue to decrease, eventually resulting in unacceptably low SNR.

Analysis results demonstrate that multiple sampling can achieve consistently higher signal-to-noise ratio at equal or higher dynamic range than using other image sensor dynamic range enhancement schemes such as well capacity adjusting. Implementing multiple sampling, however, requires much higher readout speeds than can be achieved using typical CMOS active pixel sensor (APS). This paper demonstrates, using a 640 222 512 CMOS image sensor with 8-b bit-serial Nyquist rate analog-todigital converter (ADC) per 4 pixels, that pixel-level ADC enables a highly flexible and efficient implementation of multiple sampling to enhance dynamic range. Since pixel values are available to the ADC's at all times, the number and timing of the samples as well as the number of bits obtained from each sample can be freely selected and read out at fast SRAM speeds. By sampling at exponentially increasing exposure times, pixel values with binary floating-point resolution can be obtained. The 640 222 512 ...

The pixel-level Adaptive Sensitivity technology enables image sensors to acquire wide dynamic range scenes without loss of detail, by adjusting the sensitivity of each individual pixel according to the intensity of light incident upon it. An Adaptive Sensitivity TDI (time delay and integrate) CCD sensor test circuit has been designed and fabricated. The sensor comprises 18 TDI integration stages, with a horizontal resolution of 32 pixels. The level of charge integrated in each pixel is monitored as the pixel charge packet progresses across the TDI array. If the charge accumulates to above a certain threshold level, the pixel is discharged. Such `conditional reset' mechanisms are inserted after the thirteenth stage and again after the seventeenth stage. Thus, each individual pixel may be integrated over either 1, 5, or all 18 stages. Since in TDI scanning, as in all linear imaging situations, there is no concept of "frames" and each pixel is imaged only once, the intensity sensing and t...

This paper suggests a new way of modelling color for images taken by digital cameras. We show that this color model is useful for overcoming the nonlinearity of digital camera sensors. This model is suitable for color image segmentation and enables one to easily manipulate and enhance the colors of an image. 1.

The pixel-level Adaptive Sensitivity technology enables image sensors to acquire wide dynamic range scenes without loss of detail, by adjusting the sensitivity of each individual pixel according to the intensity of light incident upon it. An Adaptive Sensitivity TDI (time delay and integrate) CCD sensor test circuit has been designed and fabricated. The sensor comprises 18 TDI integration stages, with a horizontal resolution of 32 pixels. The level of charge integrated in each pixel is monitored as the pixel charge packet progresses across the TDI array. If the charge accumulates to above a certain threshold level, the pixel is discharged. Such ‘conditional reset ’ mechanisms are inserted after the thirteenth stage and again after the seventeenth stage. Thus, each individual pixel may be integrated over either 1, 5, or all 18 stages. Since in TDI scanning, as in all linear imaging situations, there is no concept of "frames " and each pixel is imaged only once, the intensity sensing and the decision on how long to integrate must be performed 'on the fly'. But, while in regular linear sensors the perpendicular fill factor is unlimited and complex control circuits may be placed next to the detectors, the two dimensional nature of TDI sensors presents much more demanding architectural and circuit challenges. 1.