Читать книгу Multimedia Security, Volume 1 - William Puech - Страница 40

In this section, we seek to determine the compression history of an image. We will focus on the JPEG algorithm, which is nowadays the most common method to store images. Most cameras use this format but others exist, such as HEIF, used in particular in Apple products since 2017. HEIF is also a lossy compression algorithm and therefore leaves traces; nevertheless, these traces are different from the ones produced by JPEG. As we will see, the analysis of the JPEG coding of an image makes it possible to detect local manipulations. For this, the methods take advantage of the structured loss of information caused by this step in the processing chain.