OpenEXR

OpenEXR provides the specification and reference implementation of the EXR file format, the professional-grade image storage format of the motion picture industry.

	git clone https://github.com/AcademySoftwareFoundation/openexr
					

The OpenEXR File Format

The purpose of the OpenEXR format is to accurately and efficiently represent high-dynamic-range scene-linear image data and associated metadata, with strong support for multi-part, multi-channel use cases.

OpenEXR is widely used in host application software where accuracy is critical, such as photorealistic rendering, texture access, image compositing, deep compositing, and DI.

OpenEXR is a project of the Academy Software Foundation. OpenEXR is included in the VFX Reference Platform.

OpenEXR Features

• High dynamic range and color precision.

• Support for 16-bit floating-point, 32-bit floating-point, and 32-bit integer pixels.

• Multiple image compression algorithms, both lossless and lossy. Some of the included codecs can achieve 2:1 lossless compression ratios on images with film grain. The lossy codecs have been tuned for visual quality and decoding performance.

• Extensibility. New compression codecs and image types can easily be added by extending the C++ classes included in the OpenEXR software distribution. New image attributes (strings, vectors, integers, etc.) can be added to OpenEXR image headers without affecting backward compatibility with existing OpenEXR applications.

• Support for stereoscopic image workflows and a generalization to multi-views.

• Flexible support for deep data: pixels can store a variable-length list of samples and, thus, it is possible to store multiple values at different depths for each pixel. Hard surfaces and volumetric data representations are accommodated.

• Multipart: ability to encode separate, but related, images in one file. This allows for access to individual parts without the need to read other parts in the file.

• Versioning: OpenEXR source allows for user configurable C++ namespaces to provide protection when using multiple versions of the library in the same process space.

The OpenEXR Project Mission

The goal of the OpenEXR project is to keep the EXR format reliable and modern and to maintain its place as the preferred image format for entertainment content creation.

Major revisions are infrequent, and new features will be carefully weighed against increased complexity. The principal priorities of the project are:

• Robustness, reliability, security

• Backwards compatibility, data longevity

• Performance - read/write/compression/decompression time

• Simplicity, ease of use, maintainability

• Wide adoption, multi-platform support - Linux, Windows, macOS, and others

OpenEXR is intended solely for 2D data. It is not appropriate for storage of volumetric data, cached or lit 3D scenes, or more complex 3D data such as light fields.

The goals of the IlmBase project are simplicity, ease of use, correctness and verifiability, and breadth of adoption. IlmBase is not intended to be a comprehensive linear algebra or numerical analysis package.

License

OpenEXR is released under the BSD-3-Clause license. See PATENTS for license information about portions of OpenEXR that are provided under a different license.