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研究生: 張丞賦
Cheng-Fu Chang
論文名稱: 以FPGA實現即時除霧系統
A Real-Time Dehazing System Implemented on FPGA
指導教授: 王乃堅
Nai-Jian Wang
口試委員: 呂學坤
Shyue-Kung Lu
鍾順平
Shun-Ping Chung
郭景明
Jing-Ming Guo
曾德峰
Der-Feng Tseng
學位類別: 碩士
Master
系所名稱: 電資學院 - 電機工程系
Department of Electrical Engineering
論文出版年: 2021
畢業學年度: 109
語文別: 中文
論文頁數: 65
中文關鍵詞: 影像除霧暗通道先驗FPGA即時
外文關鍵詞: Dehaze, Dark Channel Prior, FPGA, Real-Time
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隨著科技迅速的發展,電腦視覺輔助系統已在生活中越來越普遍,以自動駕駛無人車為例,自駕車上裝載著影像感應器,並藉由影像感應器所拍攝到的畫面進行偵測與分類辨識,而若自駕車行駛於惡劣的環境下,可能因為鏡頭拍攝擷取到的畫面不夠清晰,行車電腦對分辨物體的能力下降導致判斷錯誤。因此為了使感測系統提高辨識正確率並隨時擁有一張清晰的場景影像,讓錯誤判讀導致事故的發生率降至最低成了一件重要的研究課題。
對於影像前處理的方面,探討如何從一個有霧的環境,將拍攝後的影像做到即時除霧並反饋於使用者。在做除霧前,我們必須得到一張有霧的圖像,並從圖像中分析因大氣懸浮粒子所產生的介質穿透率圖,再去估計整張圖片大氣光線的來源,最後將上述三者都帶入到大氣散射模型當中,便能從物理角度上還原出無霧圖像。
本篇論文會以色彩衰減先驗的方法,去訓練一組線性模型的係數,最後將除霧演算法實現在FPGA(Field Programmable Gate Array)上,當硬體接收到影像序列的輸入,首先將影像序列做縮小,並由序列中計算深度圖,從深度圖的資訊還原介質穿透率,在透過大氣光線的估計,並藉由大氣散射模型將一幅有霧圖像還原成去霧圖像。
實驗結果顯示此方法可成功從攝影鏡頭輸入並將除霧後的影像顯示輸出至螢幕上,實驗結果顯示了本系統使用了19,877(17%)個邏輯元件和3,133,376(79%)bits內部記憶體,且處理速度達到每秒175張影像(NTSC Input)。


Computer vision assistance systems have become more and more common in life. For example, the smart car is equipped with an image sensor, and the image captured by the image sensor is used for detection. If a smart car is driving in a harsh environment, it may be that the captured image is not clear enough, and the ability to distinguish objects may be reduced, resulting in judgment errors. Therefore, in order to make the sensing system have a clear scene image, improving the recognition accuracy and reducing the probability of accidents have become an important issue.
Before dehazing, we must obtain a haze image, and analyze the medium transmission map caused by atmospheric suspended particles from the image. Estimate the source of atmospheric light in the entire image, and brought into the atmospheric scattering model, then the haze-free image can be recovered.
This paper will use the color attenuation prior method to train a set of linear model coefficients. The dehazing algorithm will be displayed on the FPGA (Field Programmable Gate Array). When the hardware receives the input of the image sequence, and the depth map is calculated from the image sequence. The medium transmission map is restored from the information of the depth map. After the estimation of atmospheric light, a haze image is restored by the atmospheric scattering model.
Experimental results show that this method can successfully input from the camera and output the dehazed image to the screen, and the processing speed can reach 175 frames per second (NTSC Input).

摘要 I Abstract II 致謝 III 目錄 IV 圖目錄 VI 表目錄 IX 第一章 緒論 1 1.1研究背景 1 1.2文獻回顧 2 1.3論文目標 3 1.4論文架構 4 第二章 顏色衰減先驗演算法 5 2.1 HSV色彩空間 6 2.2大氣散射模型 7 2.3場景深度還原 8 2.3.1 線性模型 9 2.3.2資料收集 9 2.3.3訓練模型係數 10 2.4場景色彩還原 13 2.4.1大氣光的估計 13 2.4.2場景還原 14 第三章 系統硬體實現 16 3.1系統架構 16 3.2影像縮放硬體設計 17 3.3YCbCr轉RGB硬體設計 19 3.4RGB轉HSV硬體設計 20 3.5單精制浮點數轉換硬體設計 21 3.6單精制浮點數四則運算硬體設計 24 3.7指數函數硬體設計 27 3.8暗通道先驗硬體設計 28 3.9大氣光硬體設計 29 3.10有霧圖像還原無霧圖像硬體設計 31 第四章 實驗結果與分析 33 4.1軟體 33 4.1.1實驗環境規格 33 4.1.2演算法效果 33 4.2硬體 39 4.2.1實驗環境規格 39 4.2.2視訊解碼晶片簡介 41 4.2.3 VGA標準簡介 41 4.2.3攝影機簡介 42 4.2.4 DE2-115開發平台驗證 43 4.2.5 FPGA硬體資源使用 44 4.2.6 系統延遲 45 4.3訓練集分析 46 第五章 結論與未來研究方向 48 5.1結論 48 5.2未來研究方向 50 參考資料 51

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