Which steganography technique uses transform domain methods?

Which steganography technique uses transform domain methods?

• A. Substitution techniques
• B. Cover generation techniques
• C. Transform domain techniques
• D. Spread spectrum techniques

Answer: (C)

Transform domain techniques hide data by embedding it into the transform coefficients of the cover, after applying a transform such as the discrete cosine transform (DCT) or discrete wavelet transform (DWT). This means the data is stored in the frequency components rather than directly in the pixel values. In images, this is common because many image formats (like JPEG) use DCT, and altering those coefficients can be more resistant to processing like compression and minor editing. This is different from spatial-domain methods that modify pixel values directly, such as substitution of bit planes. It’s also distinct from cover generation, which creates a new cover to carry the message, and from spread spectrum techniques, which hide data by distributing it across a wide range of frequencies using a pseudorandom sequence rather than by altering transform coefficients.

Transform domain techniques hide data by embedding it into the transform coefficients of the cover, after applying a transform such as the discrete cosine transform (DCT) or discrete wavelet transform (DWT). This means the data is stored in the frequency components rather than directly in the pixel values. In images, this is common because many image formats (like JPEG) use DCT, and altering those coefficients can be more resistant to processing like compression and minor editing.

This is different from spatial-domain methods that modify pixel values directly, such as substitution of bit planes. It’s also distinct from cover generation, which creates a new cover to carry the message, and from spread spectrum techniques, which hide data by distributing it across a wide range of frequencies using a pseudorandom sequence rather than by altering transform coefficients.