Struct ContentLightLevel 

pub struct ContentLightLevel {
    pub max_content_light_level: u16,
    pub max_frame_average_light_level: u16,
}

HDR content light level metadata (CEA-861.3 / CTA-861-H).

Describes the peak brightness characteristics of HDR content. Used by AVIF, JXL, PNG (cLLi chunk), and video containers.

Fields

max_content_light_level: u16

Maximum Content Light Level (MaxCLL) in cd/m² (nits). Peak luminance of any single pixel in the content.

max_frame_average_light_level: u16

Maximum Frame-Average Light Level (MaxFALL) in cd/m². Peak average luminance of any single frame.

Implementations

impl ContentLightLevel

pub const fn new( max_content_light_level: u16, max_frame_average_light_level: u16, ) -> ContentLightLevel

Create content light level metadata.

pub fn measure( px: PixelSlice<'_>, white: DiffuseWhite, ) -> Option<ContentLightLevel>

Measure MaxCLL / MaxFALL (CTA-861.3-A) from relative-linear RGB(A) f32 pixels, with white anchoring the scale (sample 1.0 = white nits; DiffuseWhite::BT2408 — 203 — is the convention).

Semantics per CTA-861.3-A as PNG 3rd ed §11.3.2.8 imports it for stills (one still = one frame): MaxCLL is the brightest pixel’s max(R, G, B) in cd/m², MaxFALL is the image’s average of per-pixel max(R, G, B). Negative/NaN samples clamp to 0; an alpha lane is ignored; strided rows are handled.

Returns None if the descriptor is not relative-linear RgbF32/RgbaF32. This is deliberate, not a missing case: cd/m² is only defined in linear light, so a transfer function would have to be inverted first — and inverting one (PQ/HLG/sRGB → linear) is the conversion pipeline’s job, which the foundational zenpixels crate has no dependency on. To measure an integer or non-linear HDR buffer, linearize it to RgbaF32 first (zenpixels_convert::convert_buffer), then call this. Zero-area input yields Some(0, 0).

RgbF32 and RgbaF32 share one reduction (generic over the channel count); the inner loop reads whole f32s from the channel-aligned buffer so it vectorizes rather than decoding sample-by-sample.

Trait Implementations

impl Clone for ContentLightLevel

fn clone(&self) -> ContentLightLevel

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ContentLightLevel

impl Debug for ContentLightLevel

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for ContentLightLevel

fn default() -> ContentLightLevel

Returns the “default value” for a type.

impl Eq for ContentLightLevel

impl Hash for ContentLightLevel

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ContentLightLevel

fn eq(&self, other: &ContentLightLevel) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ContentLightLevel