points
Something like this:
Digital Number DN=0 remains the “NO_DATA” value
For a given DN in [1; 1;215-1], the L2A SR reflectance value will be:
L2A_SRi = (L2A_DNi + BOA_ADD_OFFSETi) / QUANTIFICATION_VALUE
https://sentiwiki.copernicus.eu/web/s2-products