基於可見光之行車夜視系統的演算法與架構設計

Algorithm and Architecture Design of Night Vision System Based on Visible Light

黃國庭(Gou-Ting Huang)

指導教授 ： 曹恆偉

共同指導教授 ： 范育成

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10524

摘要

在本論文中，我們提出一個基於影像處理的方法來設計一個低成本的車用夜視系統，這個系統用可見光攝影機擷取夜間路況，經過處理後，提供給駕駛者一個加強過後清楚的視訊，在我們提出的方法中包含了去雜訊與影像加強兩部分，去雜訊方面，依平均亮度分割圖片成亮暗兩部分，各自計算臨界值並用sobel邊緣偵測子執行邊緣偵測，得到邊緣後執行邊緣保留空間-時間去雜訊，影像加強方面，我們修改local gamma correction，以動態斜率線性轉換函數取代原有的指數函數，設定亮暗分界，調亮暗處，抑制亮處，並融入retinex的概念來微調局部對比。
最後我們將我們的演算法實現在FPGA測試版上，操作頻率是54MHz，其中內部暫存使用line buffer，並設計控制電路使得資料有規律的進出，以利簡化硬體實現。

關鍵字

去雜訊 ； 影像加強 ； 夜視系統 ； 邊緣保留 ； 可見光

並列摘要

In this thesis, we propose a method based on image processing to develop a low cost night vision system for vehicles. The system captures the road situation at night with visible light video camera and provides the driver with the enhanced clear video. In our method, our proposed method include two parts, denoising and enhancement. In denoising, we segment the image into dark part and bright part by average brightness. Calculate the thresholds and use sobel edge detection to do edge detection, respectively. After getting the edge map, we perform edge-preserving spatio-temporal filter. In enhancement, we modify local gamma correction. Replace the exponential function in it by linear function with dynamic slope. Divide the image into dark part and bright part by the value we set. Brighten the dark part and darken the bright part. Moreover, we use the concept of retinex to modify local contrast.
Finally, We implement our algorithm in FPGA chip, the clock frequency is 54MHz. Inside the chip, we use line buffer to store the temporary date. We design the control circuit to let the date get in and out regularly. This will make the hardware easy to realize.

並列關鍵字

night vision system ； denoise ； image enhancement ； edge preserve

參考文獻

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