即時解析度調變與動態範圍提升CMOS影像感測器

近幾年，先進的影像處理技術可以在影像系統中達到許多功能，例如：機器人視覺、位移偵測與目標追蹤等功能。然而隨著影像感測器空間分辨率增高，影像處理工作量隨之增加，造成系統運算上的負擔；除此之外，典型的影像感測器對照光強度呈現線性響應，與人眼視覺呈現對數響應不同，因此無法達到接近人眼感官。因此在本論文中，主要有三項研究重點，第一、透過新型相關雙重取樣電路經由類比平均方法即時將影像訊號進行壓縮，降低影像訊號量，以減少運算的複雜度，實驗結果顯示，其誤差可小於1 %。第二、將影像感測器操作在不同的積分時間長度下所得到的訊號，經由新型相關雙重取樣電路將訊號加以合成，以達到動態範圍提升功能，實驗結果顯示，此電路透過不同的時間比值設計，可得到不同程度的動態範圍提升。第三、將上述二種功能加以結合，使得新型相關雙重取樣電路同時具備即時解析度調變與動態範圍提升功能。新型相關雙重取樣電路，適用於典型的影像感測器矩陣電路中，只需要稍微修改典型相關雙重取樣電路，並且使用簡單的控制訊號，就達到上述功能。在本論文中，已將此新型設計完成於128×128之影像感測器矩陣上，並成功展現其功能。

關鍵字

CMOS影像感測器；解析度調變；動態範圍提升

並列摘要

In recent years, advance image processing techniques enables many visual functions such as, robotic vision, motion detection, and target tracking, to be integrated in an imaging system. As spatial resolution of CIS (CMOS Image Sensor) array increases, the image processing loading becomes higher and more complex. In addition, the typical optical response of conventional CIS is linear, which is often insufficient to reflect images perceived by human eyes. In this work, three major subjects are investigated. First, a proposed CDS (Correlated Double Sampling) circuit with variable resolution imaging functions through analog averaging circuits is proposed. This new scheme can effectively reduce data and computational complexity in conventional variation resolution systems. The experiment results show that this scheme introduced averaging error of less than 1 %. Secondly, the proposed CDS can capture the signals of the sensor array operating under different integration lengths, hence and successfully extend the dynamic range. The experiment results show that the pixel can gain different dynamic ranges by varying integration time ratio. Finally, by minor modification the new proposed CDS can operate under both real-time variable resolution and dynamic range boosting modes. The new operation scheme which requires only simple control signals with the modified CDS (Correlated Double Sampling) circuit is successfully demonstrated in a 128×128 CIS pixel array.

並列關鍵字

CMOS image sensor ； variable resolution ； dynamic range boosting

參考文獻

[1] H. S. P. Wong, “CMOS image sensors–Recent advances and device scaling considerations,” in IEEE IEDM Tech. Dig., 1997, pp.201-204.

[2] Sunetra K. Mendis, Eric Fossum , ”CMOS Active Pixel Sensor for Highly Integrated Imaging Systems,” IEEE J. Solid-State Circuits, vol. 32, No. 2, pp. 187-197, Feb. 1997.

[3] H. Rhodes, G. Angranov et al., “CMOS Imager Technology Shrinks and Image Performance,” Microelectronics and Electron Devices, 2004 IEEE Workshop on 2004 pp.7 - 18.

[4] H. Samet, The Design and Analysis of Spatial Data Structures. Reading, MA: Addison-Wesley, 1990.

[5] H. Samet, Applications of Spatial Data Structures:Computer Graphics, Image Processing and GIS. Reading, MA: Addison-Wesley, 1990.

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即時解析度調變與動態範圍提升CMOS影像感測器

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