libultrahdr を Homebrew でインストール

プロジェクトリンク

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コマンドとエイリアス

• ultrahdr_app

プロジェクトの歴史

Android's Ultra HDR specification defines a JPEG-based format that encodes a logarithmic range gain map. libultrahdr implements the codec side: it can compute a gain map from SDR and HDR renditions, store the base image, gain map, and metadata, and decode them back into an HDR rendering on compatible displays.

The GitHub release history starts with version 1.0.0 on October 24, 2023. The 1.1.0 release in August 2024 added image-quality features, command-line tool updates, editing support, and ISO 21496-1 standard support. The 1.4.0 release in January 2025 added per-channel content boost configuration and alternate color-space handling.

採用の歴史

Ultra HDR entered Android developer workflows with Android 14 API level 34 support for displaying Ultra HDR images. Android documentation tells app developers to detect gain maps and switch windows into HDR color mode when displaying these images.

Google's Android Developers Blog described Instagram as an early adopter that began implementing Ultra HDR in late September 2023, highlighting the format's movement from platform feature to high-volume social media use.

使われ方

Developers use libultrahdr to encode HDR still images into a backward-compatible JPEG container and to decode Ultra HDR images for HDR-capable displays. The bundled ultrahdr_app command-line tool makes it useful for testing encodes, decodes, performance, and format behavior outside Android app code.

パッケージ好きにとっての重要性

libultrahdr matters to package nerds because it turns a mobile platform media feature into a portable codec library that distributions can ship. It also captures the practical transition from SDR-only JPEG workflows to gain-map HDR images that still degrade cleanly in old software.

タイムライン

• 2023: Android 14 introduced platform support for Ultra HDR images.
• 2023: libultrahdr 1.0.0 was released on October 24, 2023.
• 2024: libultrahdr 1.1.0 added editing support and ISO 21496-1 support on August 22, 2024.
• 2024: libultrahdr 1.2.0 added a Java library and sample app on September 20, 2024.
• 2025: libultrahdr v1.4.0 was released on January 10, 2025.

Related projects

• Android 14 and later Android media APIs provide platform display support for Ultra HDR.
• ISO 21496-1 is an adjacent gain-map HDR standard named in the libultrahdr release notes.
• JPEG, XMP, and CIPA Multi-Picture Format are normative or container-level building blocks cited by the Ultra HDR specification.

ソース

• https://android-developers.googleblog.com/2024/08/instagrams-early-adoption-of-ultra-hdr-transforms-user-experience.html
• https://developer.android.com/media/grow/ultra-hdr/display
• https://developer.android.com/media/platform/hdr-image-format
• https://github.com/google/libultrahdr
• https://github.com/google/libultrahdr/releases