poka.sh

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HDR

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Radiance HDR Preview.

At a glance
Original creator Gregory Ward Larson, for the Radiance rendering system
Purpose Radiance HDR (RGBE): high-dynamic-range images, one byte each for red, green and blue plus a shared exponent byte.
Extensions .hdr
Poka parser poka-hdr
Viewer poka-image-with-meta-viewer
Depth tier Parser with a shared viewer (see Depth tiers)
Breadth tier B2 Broad (see Breadth tiers)

How much Poka reads

B2 Broad. The common content of the current and the common older versions is decoded. Some named features or versions are not, and are listed.

Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-16: parsers/poka-hdr/src/main.rs (image HdrDecoder, Reinhard tone map, MAX_DECODED 24 MiB), src/envi.rs, and the image 0.25.10 HDR decoder source. tests/samples.rs only tests the ENVI path (2 ENVI corpus files) and that quarry_01_1k.hdr is not taken for ENVI. The Radiance render path is covered only by synthetic unit tests, not by a corpus render test. Tier is for Radiance RGBE pictures; the ENVI header path (a text sidecar with no pixels, B4 in kind) is a separate format that shares the extension.

What Poka does not read

  • pictures whose floats exceed 24 MiB (larger than about 2048 x 1024) are reported, not drawn, which covers most large environment maps
  • XYZE-format Radiance pictures (FORMAT=32-bit_rle_xyze) are not converted
  • header variables (EXPOSURE, COLORCORR, PRIMARIES, VIEW, SOFTWARE) are not shown or applied
  • HDR range is lost: a fixed Reinhard tone map to 8-bit is shown
  • ENVI .hdr headers describe the raster only; the .img/.dat pixels are never read

Background

In Poka, .hdr is two formats. A Radiance picture is decoded with the image crate, tone-mapped to 8 bits and shown as a PNG; one whose decoded floats would exceed 24 MiB is reported, not drawn, which is the case for most large environment maps. A .hdr that starts with the line ENVI is the text header of a remote-sensing raster, and Poka describes that header instead.

Versions

Version Identifier Poka Note
Radiance RGBE picture #?RADIANCE Partly read Drawn when the decoded image fits 24 MiB (MAX_DECODED in main.rs); reported otherwise.
  • ENVI header (.hdr): A different format with the same extension; poka-hdr tells them apart by the first line.

Libraries

Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.

Sources