Sepia tone operation. :strength is a [0.0, 1.0] blend
factor between the identity (0.0) and the full sepia matrix
(1.0). Maps to imgix's sepia=N (N / 100) and Cloudinary's
e_sepia[:N] (N / 100, default full sepia).
Summary
Types
@type t() :: %Image.Plug.Pipeline.Ops.Sepia{strength: float()}