Crate ultrahdr_rs

Crate ultrahdr_rs 

Source
Expand description

Ultra HDR - Pure Rust encoder/decoder for HDR images with gain maps.

Ultra HDR is an image format that stores HDR (High Dynamic Range) content in a backwards-compatible JPEG file. Legacy viewers see the SDR (Standard Dynamic Range) base image, while HDR-capable displays can reconstruct the full HDR content using an embedded gain map.

§Crate Structure

  • ultrahdr_core - Core gain map math and metadata (no codec dependency)
  • ultrahdr (this crate) - Full encoder/decoder with jpegli integration

§Format Overview

An Ultra HDR JPEG contains:

  • Primary JPEG: SDR base image (8-bit, sRGB)
  • Gain map JPEG: Compressed ratio of HDR/SDR luminance
  • XMP metadata: Describes how to apply the gain map
  • MPF header: Multi-Picture Format container

§Example

ⓘ
use ultrahdr::{Encoder, Decoder, RawImage, PixelFormat, ColorTransfer};

// Encoding HDR to Ultra HDR JPEG
let hdr_image = RawImage::from_data(
    1920, 1080,
    PixelFormat::Rgba16F,
    ColorGamut::Bt2100,
    ColorTransfer::Pq,
    hdr_pixels,
)?;

let ultrahdr_jpeg = Encoder::new()
    .set_hdr_image(hdr_image)
    .set_quality(90, 85)
    .encode()?;

// Decoding Ultra HDR JPEG
let decoder = Decoder::new(&ultrahdr_jpeg)?;
let hdr_output = decoder.decode_hdr(4.0)?; // 4x SDR brightness

§Standards

This implementation follows:

Modules§

color
Color space handling: transfer functions, gamut matrices, conversions.
container
JPEG container utilities for codec-agnostic Ultra HDR support.
gainmap
Gain map computation and application.
jpeg
JPEG handling utilities.
limits
Safety limits for parsing and allocation.
luminance
Reference display luminance values (in nits).
metadata
Metadata handling for Ultra HDR images.

Structs§

Decoder
Ultra HDR decoder.
Encoder
Ultra HDR encoder.
Fraction
A fraction for ISO 21496-1 metadata encoding.
GainMap
A gain map image (8-bit grayscale or per-channel).
GainMapConfig
Configuration for gain map computation.
GainMapMetadata
Gain map metadata (linear scale values). These values describe how to interpret the gain map.
RawImage
A raw (uncompressed) image.
Unstoppable
A Stop implementation that never stops (no cooperative cancellation).

Enums§

ColorGamut
Color gamut / color space primaries.
ColorTransfer
Electro-optical transfer function (EOTF/OETF).
Error
Errors that can occur during Ultra HDR operations.
HdrOutputFormat
Output format for HDR reconstruction.
PixelFormat
Pixel format for raw images.
StopReason
Why an operation was stopped.

Traits§

Stop
Cooperative cancellation check.

Type Aliases§

Result
Result type for Ultra HDR operations.