EXRView

A VS Code viewer for OpenEXR files, built on the reference OpenEXR library (compiled to WebAssembly), so it reads everything OpenEXR reads:

• every compression codec (including DWAA/DWAB, HTJ2K, ZSTD)
• multi-part and multi-layer files, tiled and scanline, subsampled channels
• deep images, flattened front to back (plus a per-pixel sample count view)
• Cryptomatte preview with object/material names under the cursor

It runs in desktop VS Code, remote sessions and vscode.dev: the decoder runs in the webview, not on the host.

Sample images from the OpenEXR test images.

Using the viewer

Open any .exr file. Toolbar, left to right:

• Layer / Channel — every part and layer; RGB or a single channel.
• Exposure / Offset — drag sliders (Shift for fine control, scroll to step, double-click to type). Display value = value × 2^exposure + offset. E / Shift+E step the exposure.
• Normalize (N) — sets exposure and offset so the displayed values span [0, 1] (depth, ids, sample counts). Reset (R) sets both back to 0 and gamma to 1.
• Tonemapping — Gamma (value^(1/gamma), then sRGB; G / Shift+G), or a false-color colormap (Viridis, Inferno, Turbo, IceFire, Grayscale) over [0, 1] or [−1, 1].
• Pixel grid / pixel values — shown once you zoom in far enough.
• Fit (F), 100% (1), header attributes of the selected layer (I).

Scroll to zoom at the cursor, drag to pan. The status bar shows the values of every channel in the current layer under the cursor. NaN/Inf pixels are shown magenta. The display settings persist while the editor is open, and the view reloads when the file is rewritten on disk.

Development

npm install
npm run build:wasm   # needs emsdk (EMSDK env var, or ../emsdk)

License

MIT, see LICENSE. The decoder bundles OpenEXR, Imath, OpenJPH, libdeflate and Zstandard; their licenses are in ThirdPartyNotices.txt.