基於LPT與SIFT之抗幾何複製影像偵測機制

A Geometry-Distortion Resistant Image Detection System Based on Log-Polar Transform and Scale Invariant Feature Transform

陳昱維(Yu-wei Chen)

指導教授 ： 謝尚琳

大同大學/電機資訊學院/資訊工程學系所/碩士(2010年)

摘要

現今許多的複製影像偵測機制採用特徵匹配技術，對於擁有相似特徵的影像能夠快速的比對並辨認相似度。然而，幾何處理如縮小、旋轉，會對影像的特徵位置產生偏移，造成此類型偵測機制比對失敗。根據上述原因，本論文提出了一個能夠有效比對遭受幾何處理影像的偵測機制。
本機制共分為二個階段，分別為特徵生成以及影像辨認。特徵生成階段將會對機制中的每張受保護影像做對數極座標轉換以及特徵擷取，日後若要比對影像相似度則只需比對特徵即可。影像辨認階段則會取出懷疑影像的特徵並逐一與受保護影像特徵做比對。
此外，本論文也對相似影像做進一步的探討。所謂的相似影像可以分為二種，一為兩張影像中的物件非常相像，因此在特徵比對時常會誤判其為相同影像。另一種相似影像則為兩張影像中擁有完全相同的物件但拍攝角度卻並不一致，此類型也容易誤判為相同影像。針對上述問題，本論文提出了一套基於動態補償與正規化互相關法的辨認機制。實驗顯示，此機制對於上述問題能擁有良好的辨認效果。

關鍵字

影像偵測機制 ； 幾何

並列摘要

In many image detection systems, the detection results are superior to tamper distortion. However, the geometric distortions rearrange the feature positions, and this property often affects the results of feature comparison. In this thesis, the presented scheme aims at resisting the geometric distortions.
The scheme contains the feature construction phase and the comparison phase. In the feature construction phase, the scheme extracts unique features from each protected image based on Log Polar Transform and Scale Invariant Feature Transform. In the comparison phase, the scheme extracts features from the suspect image to compare each protected image.
Furthermore, this paper also focuses on similar image identification. There are two types of similar image that the scheme aims. The first type is that there are similar objects in two images. The second type is different view images. These two types of images are serious issue for feature comparison. Hence, this paper presents a scheme to solve this problem.

並列關鍵字

Image Detection System ； Geometry-Distortion

參考文獻

[1] J. O’Ruanaidh and T. Pun, "Rotation, Scale and Translation Invariant Digital Image Watermarking, " Proc. IEEE International Confemnce on Image Processing, Vol. I, pp. 536-539, 1997.

[2] C. Y. Lin, M. Wu, J. A. Bloom, I. J. Cox, M. L. Miller, and Y. M. Lui, "Rotation, Scale, and Translation Resilient Watermarking for Images, " IEEE Transactions on Image Processing, Vol. 10, No. 5, May 2001.

[3] C.S. Lu and C.Y. Hsu, "Geometric Distortion-resilient Image Hashing Scheme and its Applications on Copy Detection and Authentication, " ACM Multimedia Systems Journal, Vol. 11, No. 2, pp.159-173, Dec. 2005.

[4] D. G. Lowe, "Distinctive Image Features from Scale-Invariant Keypoints, " International Journal of Computer Vision, Vol. 60 No.2, pp.91-110, Nov. 2004.

[6] T. Massimo and G. Sandini, "On the Advantages of the Polar and Log-polar Mapping for Direct Estimation of Time-to-impact from Optical Flow, " IEEE Trans. Pattern Analys, Machine Intell, Vol. 15, No. 4, April 1993.