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By:
Nitin Mathur
EC-B
Roll No. -76
ASeminar presentation
On IMAGE AUTHENTICATION TECHNIQUE
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Image Authentication
• By data authentication we mean here a procedure capable of ensuring that data have not been tampered with and of indicating their true origin.
• There are two types of authentication schemes, which are-
1. Cryptographic data authentication.-
2. Watermarking-based authentication.
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Cryptography
• a straight forward way to provide video authentication, namely through the joint use of asymmetric key encryption and the digital Hash function
• It has mainly two functions:-> Encryption-> Decryption
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Encryption & Decryption
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Cryptographic Data Authentication
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Drawbacks of Cryptographic Authentication
• Knowledge of private key • Delay in transmission • High requirements of video camera
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Watermarking
What is a “Digital Image Watermark”
1. pattern inserted into a digital image
2. may be unique to each copy, or be common to multiple copies
A given Watermark may be 1.Unique to each copy (e.g., to identify the intended recipient), or 2.Be common to multiple copies (e.g., to identify the document source)
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Types of Watermarking
WATERMARKING
FRAGILE WATERMARKING
ROBUST WATERMARKING
INVISIBLEWATERMARKING
VISIBLE WATERMARKING
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Requirements of Watermarks
1. The watermark must be difficult or impossible to remove
2. The watermark must survive image modifications that are common to typical image-processing applications
3. An invisible watermark should be imperceptible so as not to affect the experience of viewing the image.
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Techniques of watermarking
• Spatial watermarking
• Frequency watermarking
-> by superimposing a symbol over an area of the picture.
-> be applied using color separation
-> applying a transforms like the Fast Fourier Transform (FFT), Discrete Cosine Transforms (DCT), Wavelet Transforms etc.
-> Watermark signal is applied to lower frequencies.
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The FFT Watermarking
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The Image Authentication Framework
• Watermark Embedding
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The Image Authentication Framework
• Watermark Detection
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ADVANTAGES
• Robustness to high quality lossy image compression.• Automatic discrimination between malicious and innocuous
manipulations.• Controllable visual deterioration of the VS sequence by
varying the watermark embedding power.
DISADVANTAGES
• Frame independent watermark can be easily found by comparative analysis of all image sequence •The detector should know the frame number in order to perform authenticity check.
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THANK YOU
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