Handles image transformation.

To configure it, set :image_opts in the metadata:

%{
  image_opts: %{
    sizes: [100, 200],
    transformations: [color_filter: "grayscale_bt709"]
  }
}

:sizes defines the widths of the output files to create.

:transformations defines the function name and arguments to call on the adapter. By default, the adapter is Still.Image.Preprocessor.Mogrify. However you can also include your own or make use of Still.Image.Preprocessor.Imageflow by adding :still_imageflow as a dependency and setting in your config:

config :still, :image_adapter, Still.Image.Preprocessor.Imageflow

The default quality value is 90. To change it, set the :image_quality key in the config:

config :still, :image_quality, 80

For more information see Mogrify's options or ImageMagick's docs information.

When :image_opts is not set, it copies the input file to the output file as it is.