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1.Introduction
 Information protection
 When dealing with information protection, we must distinguish between security and dependability.
 Security can be defined in terms of confidentiality, availability,integrity and authenticity .
 Dependability mostly concerns the computing system.
 It can be described as a composite of availability (of a service), reliability (continuity of service) and maintainability (ability to undergo modifications and repairs)
Watermark embedding algorithm
 Step 1: Generate an 8-bit watermark image w with the secret key shared with the detector
 Step 2: For each pixel i,
 Step 2.1: Calculate the Hamming code h(f(i), w(i)) and distance D(f(i), w(i))
 Step 2.2: Negate the LSB of f(i) if D(f(i), w(i)) = 0 or 8 (pre-processing).
 Step 3: Identify watermarkable pixels
 Step 4: For each watermarkable pixel i,
 Step 4.1: Calculate the secret dependence information s(i)
 Step 4.2: Negate the watermarkable bit of f(i) depending on the state of the pixel.
Watermark Detecting Algorithm
 Step 1: Generate an 8-bit watermark image w with the secret key shared with the embedder
 Step 2: Initialize the extracted watermark w′by letting w′ = w.
 Step 3: For each pixel i, calculate the Hamming code h(f′(i), w(i)) and
 distance D(f′(i), w(i))
 Step 4: Identify watermarkable pixels
 Step 5: For each watermarkable pixel i,
 Step 5.1: Calculate the secret dependence information s(i)
 Step 5.2: Extract watermark bit by setting w′j(i) = sj(i)
 Step 5.3: Recover original image pixel f(i) by negating the watermarkable bit of f′(i) if w′(i) = w(i).
 Two approaches are usually distinguished
 Spread-spectrum-like methods
 Quantization Index Modulation
Applications in healthcare
Watermarking: main approaches
 Methods for watermarking medical images
• Lossless/reversible watermarking
Once the embedded message has been interpreted, the watermark can be completely removed from the image, thus enabling the original image to be retrieved
• Region of non interest watermarking
An unimportant area of the image,the black background,
Illustration of the reversible watermarking method [6] used in a Magnetic Resonance Image of the Head (256x256 pixels, encoded on 12 bits),
(a) Original image,
(b) Reversible watermarked image
© Signal of difference
Interest in medical imaging
watermarking can improve data protection and content enrichment.
 Data hiding
Facilitate data management
Add value to enhance image content