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    National Tsing Hua University Institutional Repository > 電機資訊學院 > 資訊工程學系 > 博碩士論文  >  基於高頻邊緣之動態與光度預測的超高解析視訊


    Please use this identifier to cite or link to this item: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/86669


    Title: 基於高頻邊緣之動態與光度預測的超高解析視訊
    Authors: 王貞文
    Wang, Jen-wen
    Description: GH02101062631
    碩士
    資訊工程學系
    Date: 2014
    Keywords: 影片超解析度演算法;運動補償;光流;影像處理
    Abstract: 通常一段影片在以特定倍率放大後會有失真的情況,而其解決方法的程序便稱為超解析度(super resolution)演算法。在處理影片的超解析度過程中,取得相鄰幀之間的物體移動軌跡 (光流,optical flow)為重建高解析度影片的一重要步驟,而為了提高準確度及處理任意影片的能力,包含每個幀所有點構成之optical flow的計算方法被廣泛的使用,運用此方法所得到之輸出影片品質也十分突出,但卻需耗費龐大的時間複雜度。
    我們在這篇論文提出一個以高頻邊緣為處理超解析度基底的方法,在達到減少時間複雜度目的的同時也能讓輸出的影片維持很好的品質。而如何減少時間複雜度的重點在於根據人類視覺系統(HVS),只要抓取每個幀中針對人眼較為敏感的高頻邊緣部分並進行optical flow計算即可;optical flow通常是採雙向計算(順向、逆向),這是為了得到與前後幀關係進而增加準確度,但也是造成計算時間加倍的原因之一,所以在這裡我們也提出由順向optical flow推出逆向optical flow的方法,有效的減少所需要的時間。
    我們以不同的放大倍率與不同的影片做了一系列的實驗,並和現有的超解析度演算法比較,結果顯示我們提出的方法成功的達到四倍的加速並同時維持住高解析度影片的輸出品質。
    Among researches of video super-resolution (VSR), reconstruction-based method is widely used for the capability of managing arbitrary scenes. And for accuracy, full-image based motion prediction is often adopted that results outstanding outputs. But it costs huge time complexity due to the multi-level processing. In this paper, we propose an edge-based motion and intensity prediction scheme to reduce the computation cost while maintain good enough quality simultaneously. The key point of reducing computation cost is to focus on extracted edges rather than the whole frame when finding optical flows of the video sequence in accordance with human vision system (HVS). Bi-directional optical flows are usually adopted to increase the prediction accuracy but it also increase the computation time. We also propose to obtain the backward flow from foregoing forward flow prediction which effectively save the heavy load. We perform a series of experiments and comparisons between existing VSR methods and our proposed edge-based method with different sequences and upscaling factors. The results reveal that our proposed scheme can successfully keep the super-resolved sequence quality and get about five times speed up in computation time for a two by two video scaling and six times speed up for a four by four one.
    URI: http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/86669
    Source: http://thesis.nthu.edu.tw/cgi-bin/gs/hugsweb.cgi?o=dnthucdr&i=sGH02101062631.id
    Appears in Collections:[資訊工程學系] 博碩士論文

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