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Film grain is often a desirable feature in video production, creating a natural appearance and contributing to the expression of creative intent. Film grain, however, does not compress well with modern video compression standards, such as Versatile Video Coding (VVC) also known as ITU-T H.266 and ISO/IEC 23090-3. Indeed, within various filtering and lossy compression steps, film grain is suppressed without the possibility of recovering it. One option to alleviate this problem is to use lower quantization parameters to better preserve fine details such as film grain. However, this may strongly increase the bitrate. In some scenarios, information on film grain can be communicated as metadata through for instance an SEI message specified by Versatile Supplemental Enhancement Information (VSEI, also known as ITU-T Recommendation H.274 and ISO/IEC 23002-7). Thus, film grain is often modeled and removed prior to compression, and it is then synthesized at the decoder side with the aid of appropriate metadata. In addition, film grain can also be used as a tool to mask coding artifacts introduced by the compression. Different approaches have been studied for film grain modeling. In the context of the novel VVC standard, a frequency filtering solution to parameterize and synthesize film grain can be used. This paper provides an overview of such film grain VVC-compatible technology, including parameterization, signaling and decoder side synthesis. Thus, in this paper, an approach based on the frequency filtering is firstly summarized. Then, a quantitative and qualitative simulations are preformed to show the benefits of film grain parameterization in terms of the bitrate savings for the same perceived quality.
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