Struct Parameters

#[non_exhaustive]
pub struct Parameters<WpParam, T> {
    pub white_point: WpParam,
    pub adapting_luminance: T,
    pub background_luminance: T,
    pub surround: Surround<T>,
    pub discounting: Discounting<T>,
}

Parameters for CAM16 that describe the viewing conditions.

These parameters describe the viewing conditions for a more accurate color appearance metric. The CAM16 attributes and derived values are only really comparable if they were calculated with the same parameters. The parameters are, however, too dynamic to all be part of the type parameters of Cam16.

The default values are mostly a “blank slate”, with a couple of educated guesses. Be sure to at least customize the luminances according to the expected environment:

use palette::{Srgb, Xyz, IntoColor, cam16::{Parameters, Surround, Cam16}};

// 40 nits, 50% background luminance and a dim surrounding:
let mut example_parameters = Parameters::default_static_wp(40.0);
example_parameters.background_luminance = 0.5;
example_parameters.surround = Surround::Dim;

let example_color_xyz = Srgb::from(0x5588cc).into_linear().into_color();
let cam16: Cam16<f64> = Cam16::from_xyz(example_color_xyz, example_parameters);

See also Moroney (2000) Usage Guidelines for CIECAM97s for more information and advice on how to customize these parameters.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

white_point: WpParam

White point of the test illuminant, X_w Y_w Z_w. Y_w should be normalized to 1.0.

Defaults to Wp when it implements WhitePoint. It can also be set to a custom value if Wp results in the wrong white point.

adapting_luminance: T

The average luminance of the environment (test adapting field) (L_A) in cd/m² (nits).

Under a “gray world” assumption this is 20% of the luminance of the reference white.

background_luminance: T

The luminance factor of the background (Y_b), on a scale from 0.0 to 1.0 (relative to Y_w = 1.0).

Defaults to 0.2, medium grey.

surround: Surround<T>

A description of the peripheral area, with a value from 0% to 20%. Any value outside that range will be clamped to 0% or 20%. It has presets for “dark”, “dim” and “average”.

Defaults to “average” (20%).

discounting: Discounting<T>

The degree of discounting of (or adaptation to) the reference illuminant. Defaults to Auto, making the degree of discounting depend on the other parameters, but can be customized if necessary.

Implementations

impl<Wp, T> Parameters<StaticWp<Wp>, T>

pub fn default_static_wp(adapting_luminance: T) -> Self

where T: Real,

Creates a new set of parameters with a static white point and their default values set.

These parameters may need to be further customized according to the viewing conditions.

impl<T> Parameters<Xyz<Any, T>, T>

pub fn default_dynamic_wp( white_point: Xyz<Any, T>, adapting_luminance: T, ) -> Self

where T: Real,

Creates a new set of parameters with a dynamic white point and their default values set.

These parameters may need to be further customized according to the viewing conditions.

impl<WpParam, T> Parameters<WpParam, T>

pub fn bake(self) -> BakedParameters<WpParam, T>

where BakedParameters<WpParam, T>: From<Self>,

Pre-bakes the parameters to avoid repeating parts of the calculaitons when converting to and from CAM16.

Trait Implementations

impl<WpParam: Clone, T: Clone> Clone for Parameters<WpParam, T>

fn clone(&self) -> Parameters<WpParam, T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<WpParam, T> From<Parameters<WpParam, T>> for BakedParameters<WpParam, T>

where WpParam: WhitePointParameter<T>, T: Real + FromScalar<Scalar = T> + One + Zero + Clamp + PartialCmp + Arithmetics + Powf + Sqrt + Exp + Abs + Signum + Clone, T::Mask: LazySelect<T>,

fn from(value: Parameters<WpParam, T>) -> Self

Converts to this type from the input type.

impl<WpParam: Copy, T: Copy> Copy for Parameters<WpParam, T>