IMAGE SENSORS and SIGNAL PROCESSING for DIGITAL STILL CAMERAS (original) (raw)

Standard CMOS active pixel image sensors for multimedia applications

arvlsi, 1995

The task of image acquisition is completely dominated by CCD-based sensors fabricated on specialized process lines. These devices provide an essentially passive means of detecting photons and moving image data across chip. We argue that line widths in standard ...

Comparison of Global Shutter Pixels for CMOS Image Sensors

In this paper we are presenting preliminary results from 4T technology based CMOS image sensors with global shutter, i.e. all pixels in the active array integrate light simultaneously. The global shutter operation mode is particularly important for high-speed video applications, where the more commonly implemented rolling line shutter creates motion blur. Our chips were fabricated using a 0.18 micron 4T, CIS technology with pinned photodiode and transfer gate. Different from conventional 3T type CMOS image sensors with global shutter pixel, in these 4T technology based global shutter pixels, the charge is transferred, not just sampled, onto the sense node. This translates into very high sensitivity and low readout noise at low power. For an imager with 7 transistors per pixel that is operated in global shutter, "Integrate While Read" mode, we measure an input referred noise of 10 electrons. The extinction ratio at full well signal charge is ~ 97.7%.

The comparison of CCD and CMOS image sensors

2008

abstract The architectures of CCD and CMOS image sensors are introduced briefly, followed by comparison of their performances in detail. At last, the future development trends of CCD and CMOS image sensors are prospected. It is pointed out that CCD and CMOS image sensors will remain complementary and competition, and flourish the image sensor market together in predictable future.

An Ultra-High Resolution Digital Camera

The Journal of Photographic Science, 1994

We are developing a camera capable of capturing images of fine art paintings of up to one metre square at a resolution of 20 pixels per mm, based on the Kon Iron ProgRes 3012 camera which uses piezo micro-adjustment of the CCD array to produce 3000 by 2320 pixels. The new camera will incorporate an X-Y translation stage that moves the array around the image plane to acquire blocks that can be mosaiced together to form the final large digital image.

A 640×512 CMOS image sensor with ultrawide dynamic range floating-point pixel-level ADC

IEEE Journal of Solid-state Circuits, 1999

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 2 2 2 512 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 2 2 2 512 sensor is implemented in 0.35-m CMOS technology and achieves 10.5 2 2 2 10.5 m pixel size at 29% fill factor. Characterization techniques and measured quantum efficiency, sensitivity, ADC transfer curve, and fixed-pattern noise are presented. A scene with measured dynamic range exceeding 10 000 : 1 is sampled nine times to obtain an image with dynamic range of 65 536 : 1. Limits on achievable dynamic range using multiple sampling are presented.

Evaluation and Characterization of a Logarithmic Image Sensor

2013

In this thesis, issued by Axis Communications AB, a CMOS-type image sensor with a logarithmic response and wide dynamic range capabilities was evaluated and characterized with respect to signal response and noise characteristics. The evaluation was performed in the context of the need for wide dynamic range imaging in video surveillance. Noise characteristics were thoroughly evaluated with measurements performed with an integrating sphere. Additionally some aspects of temperature dependence of the device were investigated. The dynamic range was measured with a laser diffraction setup. The capability of the sensor to accurately capture motion was also investigated. I want to thank my supervisor Pelle Ohlsson for valuable comments and for putting up with a somewhat chaotic hand-in schedule. Finally a special thanks to all the people at Axis Communications that I have met while I have been working on this thesis and especially the people at the Department of Fixed Cameras/Fixed Domes for their companionship and support.

Low-power digital image sensor for still-picture image acquisition

Proceedings of …, 2001

This article presents the design and realization of a CMOS digital image sensor optimized for button-battery powered applications. First, a pixel with local analog memory was designed, allowing efficient sensor global shutter operation. The exposure time becomes independent on the ...