EXRs

EXRs, short for OpenEXR, are a high dynamic range image file format widely used in visual effects and computer graphics. The format is designed to preserve floating-point color data with very wide tonal range and high precision, making it suitable for rendering, lighting, and compositing workflows where downstream decisions depend on accurate color and exposure information. OpenEXR originated at Industrial Light & Magic and was released as an open standard in the early 2000s; it is maintained by the OpenEXR project with broad community involvement.

A defining feature of EXRs is their flexibility in data organization. Images can be stored as either scanline or tiled data, enabling efficient access patterns for rendering and compositing. EXRs support multiple channels per pixel, which can include standard color channels (such as R, G, B, A) and an arbitrary set of custom channels (for example Z for depth, velocity, or other render passes). The format also supports multi-part files and deep image data, where each pixel can contain multiple samples, enhancing occlusion and transparency handling in compositing.

OpenEXR provides a range of compression schemes, including lossless and lossy options, to balance file size and image fidelity. Common methods include PIZ, ZIP, RLE, and the B44 family, among others. This variety allows users to optimize storage for large, high-precision renders without sacrificing important detail.

Usage and support: EXRs are widely adopted in film, animation, and game pipelines. They are supported by major renderers and composition tools (for example, Nuke, Houdini, Maya, and many image editors via libraries). The format remains a staple for storing high-dynamic-range imagery, multi-channel passes, and deep image data in professional workflows.