hdrrgbe

Hdrrgbe refers to a high dynamic range (HDR) color encoding that combines HDR imaging with the RGBE (red, green, blue, exponent) format. It is most closely associated with the Radiance HDR image format, which uses RGBE to store wide-range color data in a compact 32-bit per pixel representation.

In RGBE encoding, each pixel consists of four 8-bit components: R, G, B, and E. The R, G, and B values act as mantissas, while E is a shared exponent that scales all three channels. If R, G, and B are zero, E is typically zero to indicate black. When nonzero, the stored mantissas are interpreted in combination with the exponent to reconstruct a high dynamic range radiance value. This approach allows a broad range of intensities to be represented using only 32 bits per pixel, enabling efficient storage and transfer for HDR workflows.

Hdrrgbe is favored in certain rendering and imaging pipelines because it provides a simple, hardware-friendly way to store HDR data without resorting to full floating-point per channel. It supports tone mapping and color grading by providing access to linear or near-linear radiance values after decoding.

Limitations of hdrrgbe include quantization from 8-bit mantissas and the shared exponent, which can introduce banding and limit precision compared to full floating-point representations. It is also less flexible for extremely high dynamic ranges or precise color operations. Nevertheless, HDR RGBE remains a foundational format in some legacy and specialized HDR workflows, and many tools can convert between RGBE and floating-point representations for processing and display.