@type background_option() :: {:background, Image.BackgroundColor.spec() | nil}

A background fill option for a mapim-based transformation.

@type background_options() :: [interpolate_option() | background_option()]

Interpolation and background options for transformations that expose canvas.

@type extend_mode() :: :background | :copy

How the interpolator synthesizes the one-pixel fringe just beyond the content edge when resampling boundary pixels.

• :background (the default) blends the fringe toward the :background color. This is correct whenever the transform exposes canvas.
• :copy clamps to the nearest content pixel. Use it when the content fills the whole canvas, where the default would leave a faint border along the outermost row and column.

@type extend_option() :: {:extend_mode, extend_mode()}

An interpolation-boundary option for a mapim-based transformation.

@type interpolate() :: :nearest | :bilinear | :bicubic | :lbb | :nohalo | :vsqbs

The interpolators that may be selected with the :interpolate option (descriptions from vips -l interpolate):

• :nearest - nearest-neighbour interpolation
• :bilinear - bilinear interpolation
• :bicubic - bicubic interpolation (Catmull-Rom)
• :lbb - reduced halo bicubic
• :nohalo - edge sharpening resampler with halo reduction
• :vsqbs - B-Splines with antialiasing smoothing

:bilinear is the default except for Image.distort/4, which retains its existing :bicubic default.

@type interpolate_option() :: {:interpolate, interpolate()}

An interpolation option for a mapim-based transformation.

@type interpolate_options() :: [interpolate_option()]

Interpolation options for transformations with fixed boundary handling.

@type t() :: [interpolate_option() | background_option() | extend_option()]

Interpolation, background and boundary options for a mapim-based transformation.