L2 trims for Dolby Vision
The minimum requirement for Dolby Vison is that your HDR project must by analyzed for L1 Metadata on a shot per shot basis. With this being said, it is perfectly acceptable to deliver your HDR Graded images or mezzanine file along with the minimum L1 metadata derived from the Dolby Vision algorithm. However, it is commonly and widely expected that this minimum is not enough, and in most instances, you will be asked to also supply L2 Secondary trims for one or more Target Displays. When running Metafier, the below warning flag will be displayed if no L2 Trims are present.
Trimming for L2
Most studios and distributors alike require that, at the minimum, you do an L2 color Trim pass at 100Nits in Rec709 gamma 2.4. Dolby Best Practices suggest that after you complete your HDR Grade, and analyze your timeline for L1 metadata, you then should QC the mapped version. It is a good time at this point to Trim for L2 at the 100Nit Target Display. This will ensure that you will be delivering the best possible mapping, along with a first pass color and Metadata check.
If no L2 Trimming was required and the Colorist has received a pass in QC, then this is perfectly acceptable. Again, however, this is not the typical case as most clients will require that L2 Trims are present and are dynamically changing from shot to shot.
It is always best to consult with the content owners and be knowledgeable and up to date regarding Delivery Specifications.