HDR to PNG

HDR (Radiance RGBE, also .pic) stores a much wider brightness range than a normal photo - from deep shadows to a direct light source in a single image. The format is used mainly in 3D software and renderers for light probes and environment maps that supply a scene with realistic lighting. Browsers cannot open HDR - this tool reads the file with its own decoder and shows it as PNG.

The decoder understands both common scanline encodings: the older flat form with its built-in run-length trick, and the newer, per-channel adaptive RLE encoding. Every RGBE pixel (three colour channels plus a shared exponent) is converted into a linear brightness value.

Honest about the technique: an 8-bit PNG cannot hold HDR's huge brightness range, so the result is a tone-mapped preview, not a lossless copy of the original data - the raw data would need its own HDR-capable output format. A fixed exposure plus a 1/2.2 gamma curve map the brightness down to 8 bit; the exposure slider brightens or darkens the preview as needed.

You will typically encounter HDR when a renderer, a 3D tool or a 360-degree light scan has output a .hdr or .pic file and you want to view it briefly without specialised software, or embed it in a document. The conversion runs entirely locally, even offline - nothing is uploaded.

Specifications

In 3 steps

1. Drop or select your HDR/RGBE file.
2. Adjust the exposure if needed.
3. Download the tone-mapped PNG.

Limitations: The result is a tone-mapped 8-bit preview (fixed exposure + 1/2.2 gamma), not a lossless copy of the raw HDR data. Both the flat/old-RLE and the new adaptive scanline encoding are supported; a file without a valid #?RADIANCE/#?RGBE marker is honestly rejected. The PNG is opaque.

FAQ

Related tools

DDS to PNG · PCX to PNG · WBMP to PNG