PureJsImage · JPEG XL

JPEG XL progressive and selective decoding

Read real early stages, scaled output and viewports in a worker. Compare source access with HTTP transfer without loading a full image first.

These tools use the current repository build. Repository functionality may be newer than the npm release. Static lossy encoding is qualified; lossy animation remains Experimental.

Open

Local JPEG XL

Explicit HTTP Range URLScale denominatorViewport zoomHorizontal positionVertical position

Generated samples: repository MIT fixtures. File limit 64 MiB. Previews at most four megapixels. Cancellation discards the worker session; retry reopens the same file.

Try a sample or open a local file.

Actual stages and source reads

Teal: first source read. Orange: repeated read. This map shows library source requests, not HTTP packets. HTTP transfer, cache and managed working bytes are reported separately. Unavailable measurements remain null.

Timing, metadata and numeric evidence

No file opened.

Browser API

import { openJpegXlSession } from 'purejsimage/jpegxl'
const session = await openJpegXlSession(file)
try {
  for await (const event of session.progressive({scaleDenominator: 8})) {
    console.log(event.type)
    if (event.type === 'block') event.block.release?.()
  }
} finally { await session.close() }

Run codec work in a worker. The example uses the same public APIs as this tool. Unsupported selective dependencies are reported as fallbacks or errors; a displayed image does not prove selective access.