Enum Quality 

#[non_exhaustive]
pub enum Quality {
    ApproxJpegli(f32),
    ApproxMozjpeg(u8),
    ApproxSsim2(f32),
    ApproxButteraugli(f32),
}

Quality/compression setting.

All variants map to internal quality through empirical lookup tables. Results vary by image - these are rough approximations, not guarantees.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

ApproxJpegli(f32)

Approximate jpegli quality scale (this is a fork, not exact jpegli). Range: 0.0–100.0, where ~90 is visually lossless for most images.

ApproxMozjpeg(u8)

Approximate mozjpeg quality behavior. Range: 0–100. Maps to quality producing similar file sizes.

ApproxSsim2(f32)

Approximate SSIMULACRA2 score target. Range: 0–100 (higher = better). 90+ is roughly visually lossless.

ApproxButteraugli(f32)

Approximate Butteraugli distance target. Range: 0.0+ (lower = better). <1.0 excellent, <3.0 good.

Implementations

impl Quality

pub fn to_internal(&self) -> f32

Convert to internal quality value (0.0-100.0 scale).

pub fn from_quality(q: f32) -> Self

👎Deprecated since 0.5.0: Use Quality::from(f32) or Quality::ApproxJpegli(f32) instead

Create quality from a 0-100 scale value.

This is equivalent to Quality::ApproxJpegli(q) or Quality::from(q).

pub fn from_distance(d: f32) -> Self

👎Deprecated since 0.5.0: Use Quality::ApproxButteraugli(f32) instead

Create quality from butteraugli distance (backward compatibility).

This is equivalent to Quality::ApproxButteraugli(d).

pub fn Traditional(q: f32) -> Self

👎Deprecated since 0.5.0: Use Quality::ApproxJpegli(f32) instead

Backward-compatible constructor matching old Quality::Traditional(f32).

pub fn to_distance(&self) -> f32

Convert to butteraugli distance.

Uses the exact same formula as C++ jpegli’s jpegli_quality_to_distance.

Trait Implementations

impl Clone for Quality

fn clone(&self) -> Quality

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Quality

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

Formats the value using the given formatter.

impl Default for Quality

fn default() -> Self

Returns the “default value” for a type.

impl From<f32> for Quality

fn from(q: f32) -> Self

Converts to this type from the input type.

impl From<i32> for Quality

fn from(q: i32) -> Self

Converts to this type from the input type.

impl From<u8> for Quality

fn from(q: u8) -> Self

Converts to this type from the input type.

impl PartialEq for Quality

fn eq(&self, other: &Quality) -> 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 Copy for Quality

impl StructuralPartialEq for Quality