# `Color.Oklab`

Oklab perceptual color space (Björn Ottosson, 2020).

Oklab is defined relative to CIE XYZ under the D65 reference white
with `Y ∈ [0, 1]`. Conversions here assume the input `Color.XYZ` is
already D65; if it is tagged with a different illuminant you should
chromatically adapt it first with `Color.ChromaticAdaptation`.

# `t`

```elixir
@type t() :: %Color.Oklab{
  a: number() | nil,
  alpha: number() | nil,
  b: number() | nil,
  l: number() | nil
}
```

# `from_xyz`

Converts a CIE `XYZ` color (D65/2°) to Oklab.

### Arguments

* `xyz` is a `Color.XYZ` struct. Its illuminant should be `:D65`;
  if not, adapt first with `Color.ChromaticAdaptation`.

### Returns

* A `Color.Oklab` struct.

### Examples

    iex> xyz = %Color.XYZ{x: 0.95047, y: 1.0, z: 1.08883, illuminant: :D65, observer_angle: 2}
    iex> {:ok, oklab} = Color.Oklab.from_xyz(xyz)
    iex> {Float.round(oklab.l, 3), abs(oklab.a) < 1.0e-4, abs(oklab.b) < 1.0e-4}
    {1.0, true, true}

# `to_xyz`

Converts an Oklab color to a CIE `XYZ` color (D65/2°).

### Arguments

* `oklab` is a `Color.Oklab` struct.

### Returns

* A `Color.XYZ` struct tagged D65/2°.

### Examples

    iex> {:ok, xyz} = Color.Oklab.to_xyz(%Color.Oklab{l: 1.0, a: 0.0, b: 0.0})
    iex> {Float.round(xyz.x, 4), Float.round(xyz.y, 4), Float.round(xyz.z, 4)}
    {0.9505, 1.0, 1.0883}

---

*Consult [api-reference.md](api-reference.md) for complete listing*