Đang chuẩn bị liên kết để tải về tài liệu:
Introduction to Watermark

Recent advancements in computer technologies offer many facilities for duplication, distribution, creation, and manipulation of digital contents. Encryption is useful for transmission but does not provide a way to examine the original data in its protected form.Receiver architecture of the proposed method Current layer is decrypt by the key Ki extracted from past layer The user key Gi should be obtained before receiving media data, for instance, by manually or automatically update after subscription. | Introduction to Watermark Advisor：杭學鳴 教授 Student：朱育成 Outline Review of watermarking Applications and examples of watermarking Some architectures of watermarking combined with other techniques Motive of watermarking Recent advancements in computer technologies offer many facilities for duplication, distribution, creation, and manipulation of digital contents. Encryption is useful for transmission but does not provide a way to examine the original data in its protected form. Watermarking process Embedding stage Spatial domain flipping the low-order bit of each pixels Frequency domain embedding the watermark in mid-frequency components relatively robust to noise, image processing and compression the quality of the host image will be distorted significantly if too much data is embedded Distribution stage Compression, transmission error, and common image processing are seen as an attack on the embedded information Watermarking process Extraction stage Blind – extraction without original . | Introduction to Watermark Advisor：杭學鳴 教授 Student：朱育成 Outline Review of watermarking Applications and examples of watermarking Some architectures of watermarking combined with other techniques Motive of watermarking Recent advancements in computer technologies offer many facilities for duplication, distribution, creation, and manipulation of digital contents. Encryption is useful for transmission but does not provide a way to examine the original data in its protected form. Watermarking process Embedding stage Spatial domain flipping the low-order bit of each pixels Frequency domain embedding the watermark in mid-frequency components relatively robust to noise, image processing and compression the quality of the host image will be distorted significantly if too much data is embedded Distribution stage Compression, transmission error, and common image processing are seen as an attack on the embedded information Watermarking process Extraction stage Blind – extraction without original image Semi-blind – rely on some data or features Non-blind – need original image Detection stage Evaluate the similarity between the original and detected watermark False positive：watermark is detected although there is none False negative：no watermark is detected while there is one Watermarking properties Perceptual transparency Robustness The mark should resist to Common signal processing like lossy compression Geometric transformation like image rotation, scaling, and cropping Security How easy it is to intentionally remove a watermark Data capacity Amount of information that can be stored within the content Categories of digital watermark Perceptible Imperceptible Robust ownership assertion Fragile indicate modifications of the content Semi-fragile differentiate between lossy transformation that are “info. preserving” and lossy transformation which are “info. altering” Applications Copyright Protection Invisible watermark which can tolerate malicious and unintentional attacks It does