TIFF/BigTIFF

View TIFF and BigTIFF images directly in VS Code, including files far larger than memory.

Open any .tif, .tiff, .btf, .tf8 or .tf2 file and it opens in the viewer.

Features

• Classic TIFF and BigTIFF (64-bit offsets), little- and big-endian.
• Huge images: the image is shown as tiles, like a map. Only the tiles in view are read, at the level of detail the zoom needs: a rough overview first, then sharper tiles as they arrive. Multi-gigabyte files are never loaded whole, and tiles already shown are kept for panning and zooming back.
• Gigapixel images without overviews (e.g. whole-slide scans): the overview appears within about a second, zooming into any area shows it at full resolution almost immediately, and the zoomed-out view sharpens progressively, starting from the centre.
• Fast JPEG: JPEG tiles are decoded by the browser's native decoder, in parallel, and at 1/2, 1/4 or 1/8 size when that is all the zoom needs.
• Pyramids / overviews (e.g. Cloud Optimized GeoTIFF): the smallest level that is sharp enough is used automatically.
• Multi-page files: switch pages from the toolbar or with PageUp / PageDown.
• Compression: none, LZW, Deflate, JPEG, PackBits, Zstandard, WebP, LERC, and CCITT fax (modified Huffman RLE, Group 3, Group 4).
• Pixel formats: 1 to 64 bits per sample, unsigned and signed integers, 16/32/64-bit floating point, tiled or striped, chunky or planar.
• Colour models: grayscale (WhiteIsZero / BlackIsZero), RGB, palette, CMYK, YCbCr, CIE L*a*b*, with alpha (associated or unassociated).
• High bit depth and float data are contrast-stretched: min–max, 2%–98%, or the full range of the data type. NaN and GDAL NoData pixels are shown as transparent.
• Pixel readout: the status bar shows the coordinates and the raw sample values under the cursor.
• Info panel: format, byte order, dimensions, bit depth, compression, tiling, pyramid levels, and common tags (description, software, date, resolution, GeoTIFF EPSG code, …).
• Reloads automatically when the file changes on disk.

Controls

Using another editor for TIFF files

This viewer is registered as the default editor for TIFF files. To open a file with something else, right-click it and choose Open With…. To change the default, use the workbench.editorAssociations setting.

Limitations

• Not supported: JPEG 2000 (e.g. some Aperio SVS), old-style JPEG (compression 6), LZMA, JPEG XL, and uncompressed chroma-subsampled YCbCr.
• Pyramid levels stored in SubIFDs (as in some OME-TIFF files) are not used; those images are rendered from full resolution.
• A sharp whole-image view of a huge image without pyramid levels needs every tile of the file, so zoomed all the way out it sharpens over a while (about 2 minutes for a 52-gigapixel, 9 GB slide); a rough overview is shown meanwhile. Zooming in only reads the area in view.

Development

npm install
npm run build          # bundle into dist/
npm run typecheck
python3 test/make_fixtures.py   # needs numpy, tifffile, imagecodecs, Pillow
npm test               # decoder tests against the fixtures
npm run package        # build tiff-bigtiff-<version>.vsix

Press F5 in VS Code to launch an Extension Development Host.

How it works

• src/tiffEditor.ts: the custom editor in the extension host. It serves byte ranges of the file with positional reads.
• src/webview/main.ts: the viewer UI: canvas, zoom/pan, the display tile pyramid, info panel.
• src/webview/worker.ts: a Web Worker that parses and decodes the TIFF with geotiff.js, using a block-cached byte-range source (messageSource.ts).
• src/webview/tiff.ts: page/pyramid discovery, chunked region reading with box-filter or nearest-neighbour downsampling, and colour conversion.
• src/webview/ccitt.ts: CCITT T.4 / T.6 fax decoder.
• src/webview/jpeg.ts: JPEG tile decoding with the browser's native decoder, optionally at reduced size (geotiff.js' decoder as fallback).

License

MIT. Bundles geotiff.js (MIT).