Читать книгу Multimedia Security, Volume 1 - William Puech - Страница 27

Demosaicing is presented in more detail in section 1.2.2. After this step, the noise at each pixel is correlated with its neighbors. After demosaicing, each channel has a different noise curve since channels are processed differently by the demosaicing algorithm.

In addition, the noise curves calculated using Ponomarenko et al.’s method and those obtained from the temporal series no longer match. This is due to the fact that Ponomarenko et al.’s algorithm assumes white noise and estimates noise at high frequencies, which are affected by demosaicing. As the image processing chain is sequential, the temporal noise curves and those measured on a single image will no longer match after demosaicing.