Secure Color Imaging

In digital imaging, visual data is massively accessed, distributed, manipulated and stored using communication and multimedia technology. To prevent unauthorized access, illegal copying and distribution, modern communication and multimedia systems utilize digital rights management (DRM) solutions to ensure media integrity, secure its transmission over untrusted communication channels and protect intellectual property rights [1], [2], [3]. Two fundamental DRM frameworks, i.e. watermarking [4] and encryption [5], have been suggested for protecting and enforcing the rights associated with the use of digital content [6]. Watermarking technologies are used for tasks such as identification of the content origin, copy protection , tracing illegal copies, fingerprinting, and disabling unauthorized access to content [7]. The image watermarking process embeds data, the so-called watermark, into the host image. Basically, watermarking can be performed in the spatial or frequency domain of the host image and the visual content can be protected by embedding visible or imperceptible watermarks [1]. Examples of color watermarking solutions which operate on different principles can be found in [8], [9], [10], [11]. Essential secure characteristics can be obtained by additive, multiplicative or quantization embedding. The watermark should be robust to various attacks and attempts for its removal, damage or unauthorized detection. After the transmission of watermarked images, the watermark is extracted using the secret key or blind extraction techniques. Note that most watermarking techniques are symmetric, i.e. the embedding and detection key are identical. Encryption technologies ensure protection by scrambling the visual data into unrecognizable and meaningless variants [7], [12], [13]. In general, this transformation should be reversible in order to allow for