實作網路攝影機之自動對焦與變焦追蹤

Implementation of Auto Focus and Zoom Tracking for IPNetCAM System

黃耀正(Yao-Cheng Huang)

指導教授 ： 詹景裕

國立臺北大學/電機資訊學院/電機工程研究所/碩士(2011年)

摘要

自動對焦(Auto Focus)和變焦追蹤(Zoom Tracking)主要應用在IPNetCAM (IP Network Camera)系統中，本文針對如何在嵌入式系統(embedded system)中應用自動對焦及變焦追蹤技術，提出實作數據與成果，用來解決影像失焦問題。自動對焦主要成果為減少搜尋次數和對焦時間，快速呈現最佳清晰影像品質。變焦追蹤主要成果，當影像放大(Zoom In)至縮小(Zoom Out)過程中，維持影像清晰的品質。
在系統實作部份，IPNetCAM 硬體採用TI DM365平台，軟體使用Linux 作業系統。自動對焦實作方面採用適應性搜尋演算法，在變焦區域範圍內與全域搜尋法做比較，主要改善搜尋時間約10%，減少搜尋次數約25%。變焦追蹤實作採用查表法，查表值來源是經由實作結果產生。過程是將物體置於不同距離，量測對焦與變焦曲線關係。當鏡頭在變焦的過程中，能即時移動對焦鏡頭，保持影像清晰。

關鍵字

自動對焦、對焦值、H3A、德州儀器、變焦追蹤。

並列摘要

Auto Focus (AF) and Zoom Tracking (ZT) are majorly applied to IPNetCAM (IP Network Camera) system. In this paper, we implement the auto focus and zoom tracking technology to solve the problem of out of focus in TI’s embedded system. The realization of auto focus is to reduce the number and time of search, and show the clearest images quickly. Meanwhile, the zoom tracking keeps images clear during Zoom In and Zoom Out operations.
Furthermore, we applied the platform of TI DM365 hardware and the Linux operating system to implement the IPNetCam system. The realization of auto focus using adaptive search algorithm is about 10% faster and 25% less in term of number of search, comparing with global search in the zoom range. Zoom tracking is implemented by using the lookup-table generated by the experimental result. During the process, we can measure the relative curve of focus and zoom when the object is placed at different distances. Our system can move the focus lens immediately to keep images clear as well during the zoom operation.

並列關鍵字

Auto Focus, Focus Value, H3A, TI, Zoom Tracking.

參考文獻

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