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Li X.,Tianjin University | Li X.,Brigates Microelectronics | Yao S.,Tianjin University | Yao S.,Brigates Microelectronics | And 4 more authors.
Chinese Journal of Sensors and Actuators | Year: 2013

A new CMOS image sensor technology using combination rolling shutter to increase the dynamic range is described. Known from former methods, multiple rolling shutters are alternated in a single frame time. According to the different exposure parameters, sensor outputs different images, which combined to a wide dynamic range picture at last. By well using the free circuit resources when rolling shutter, this technology effectively shortens the time spacing between the two adjacent imaging. This presented method makes the rolling shutter interlaced to achieve the multiple imaging of the target object, so it has made a great improvement in term of system efficiency and output response speed.


Zhang Y.,Hangzhou Dianzi University | Wang G.,Hangzhou Dianzi University | Xu J.,Tianjin University | Shi Z.,Tianjin University | Dong D.,Brigates Microelectronics
Signal Processing | Year: 2012

Single sensor digital color still/video cameras use color demosaicking to reproduce full color images from color filter array (CFA) data. The quality of interpolated image will be degraded due to the sensor noise introduced during the image capture process. Many conventional demosaickingdenoising solutions adopt the channel-dependent noise model, which may fit the CMOS/CCD image sensor less than signal-dependent noise model. In this paper, the wavelet sub-band decomposition and synthesis are applied to interpolate the CFA data with signal-dependent noise model. The major contributions of this work include: (1) The combination of LMMSE and statistical calculation in wavelet domain are utilized to suppress the signal-dependent noise, which is separated into additive noise and multiplicative noise. (2) In CFA data, it has been verified that the quantitative relationship between the current pixel and the adjacent pixel, which locate in the same edge. Both simulated and real CFA images are employed to compare the proposed algorithm with the state-of-the-art techniques reported in the literature. The experimental results confirm that our method outperforms them both on demosaicking performance and on computational cost, when they process the noisy color filter array data. © 2011 Elsevier B.V. All Rights Reserved.


Zhang Y.,Hangzhou Dianzi University | Wang G.,Hangzhou Dianzi University | Xu J.,Tianjin University | Shi Z.,Tianjin University | And 3 more authors.
Signal Processing | Year: 2014

Many conventional denoising solutions adopt the channel-dependent noise model, which is less suitable than signal-dependent noise model to describe the noise characteristic of CMOS image sensor. In this paper, the cascaded Kalman filter is designed to eliminate the signal-dependent random noise from the raw data of CMOS image sensor. The major contribution of this work is that it establishes the state equation corresponding to the circuit structure of sensor pixel, instead of designing the denoising algorithm only from a mathematical point of view. The experimental results confirm that the performance of the proposed method outperforms the conventional ones. © 2014 Elsevier B.V.


Zhang Y.,Hangzhou Dianzi University | Wang G.,Hangzhou Dianzi University | Xu J.,Tianjin University | Shi Z.,Tianjin University | Dong D.,Brigates Microelectronics
Optics and Laser Technology | Year: 2014

The modified gradient edge detection method applied in demosaicing the color filter array image is proposed in this paper. Firstly, the adjacent pixels are ranged from large to small. Then, the absolute differences of sorted pixels are calculated to analyze the distribution of the possible edge. Finally, the arithmetic operators being along the possible edge and that being across the possible edge are designed to estimate the accurate edge information. The experimental results verify that the proposed method gives better performance than the traditional gradient edge detection methods, and can discriminate the accurate edge, even where the gradients in different direction are close. © 2014 Elsevier Ltd.


Zhang Y.,Hangzhou Dianzi University | Wang G.,Hangzhou Dianzi University | Xu J.,Tianjin University | Shi Z.,Tianjin University | Dong D.,Brigates Microelectronics
Signal Processing | Year: 2013

A novel approach to get the robust high-high frequency sub-band (HHFSB) of the missing color channel for reconstructing the inter-channel weak correlated color filter array (CFA) image is proposed in this paper. This algorithm can adaptively adopt one of the two distinct schemes to estimate the HHFSB of the missing color channel in each local region according to the correlation coefficient of the local inter-channel HHFSB. The experimental results confirm that the whole HHFSB of the missing color channel achieved from the proposed method is more accurate and closer to the actual one reported from the state-of-the-art approaches. © 2012 Elsevier B.V.


Patent
Brigates Microelectronics | Date: 2012-09-24

An image sensor and an image processing system. The image sensor comprises: a CMOS photosensitive array used for converting an optical signal into an electrical signal; a control signal conversion circuit used for converting into a second control signal a first control signal for driving a CCD photosensitive array to operate, the first control signal at least comprising a vertical transfer signal, a horizontal transfer signal, an electronic shutter signal and a read-out clock signal, and the second control signal at least comprising a column address signal, a row reset control signal and a row read-out control signal; a row selection circuit used for generating a row reset signal according to the row reset control signal and generating a row read-out signal according to the row read-out control signal; and a column selection circuit used for conducting column gating on the CMOS photosensitive array under the control of the column address signal and outputting a column read-out signal. The technical solution of the present invention achieves the compatibility substitution of a CCD image sensor and a CMOS image sensor.


Patent
Brigates Microelectronics | Date: 2013-06-07

A CMOS image sensor, a pixel unit and a control method thereof are provided. The pixel unit includes: a photoelectric conversion unit, an isolation transistor, a storage unit and a reading unit, wherein a first terminal of the isolation transistor is connected to the photoelectric conversion unit, a second terminal of the isolation transistor is connected to the storage unit and the reading unit; and wherein the storage unit comprises a first switch unit, a second switch unit, a first storage capacitor, a second storage capacitor and a reset unit, the first switch unit is adapted for controlling the first storage capacitor to be charged or discharged, the second switch unit is connected to the second storage capacitor and is adapted for controlling the second storage capacitor to be charged or discharged. The pixel unit improves signal-to-noise ratio of image signals generated by the pixel unit.


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