ome-tiled

An adapter for tiled that serves OME-Zarr images as arrays with their axis names, which tiled's own Zarr adapter leaves out.

Install

With uv (recommended):

uv add ome-tiled

With pip:

pip install ome-tiled

Install it on the server, and also wherever tiled register runs: registering opens each store through the adapter on the registering side.

To write Bluesky runs into a catalog with bluesky-tiled-plugins, install the bluesky extra: uv add "ome-tiled[bluesky]".

Usage

Serve a directory, letting ome-tiled find the OME-Zarr stores in it:

tiled serve directory data/ \
    --adapter application/x-ome-zarr=ome_tiled:OmeZarrAdapter \
    --mimetype-hook ome_tiled:detect

Each image then reads as one array whose dims are its axis names:

from tiled.client import from_uri

client = from_uri("http://localhost:8000", api_key="...")
client["stack"].structure().dims  # ('t', 'z', 'y', 'x')

The hook recognizes a store by its metadata, whatever it is called. Stores named *.ome.zarr can be routed by name instead, with --ext .ome.zarr=application/x-ome-zarr in place of --mimetype-hook.

From a configuration file

Register the adapter in the server's configuration:

# config.yml
trees:
  - tree: catalog
    path: /
    args:
      uri: ./catalog.db
      init_if_not_exists: true
      readable_storage:
        - data/
      adapters_by_mimetype:
        application/x-ome-zarr: ome_tiled:OmeZarrAdapter

Then start the server and register the directory:

tiled serve config config.yml --api-key secret
tiled register http://localhost:8000 data/ --api-key secret \
    --adapter application/x-ome-zarr=ome_tiled:OmeZarrAdapter \
    --mimetype-hook ome_tiled:detect

From Python

from tiled.catalog import from_uri

catalog = from_uri(
    "catalog.db",
    readable_storage=["data/"],
    init_if_not_exists=True,
    adapters_by_mimetype={"application/x-ome-zarr": "ome_tiled:OmeZarrAdapter"},
)

tiled.server.simple.SimpleTiledServer takes no adapters, so add the adapter to its catalog after starting the server and before registering anything:

from tiled.server.simple import SimpleTiledServer

from ome_tiled import OME_ZARR_MIMETYPE, OmeZarrAdapter

server = SimpleTiledServer(readable_storage=["data/"])
server.catalog.context.adapters_by_mimetype.maps[0][OME_ZARR_MIMETYPE] = OmeZarrAdapter

Registering by hand

tiled answers a registered node's structure and metadata from its database, so a registration made with client.new has to store the adapter's own, or the node reads without its axis names:

from tiled.structures.core import StructureFamily
from tiled.structures.data_source import Asset, DataSource, Management

from ome_tiled import OME_ZARR_MIMETYPE, OmeZarrAdapter

uri = "file:///data/stack.ome.zarr"
adapter = OmeZarrAdapter.from_uris(uri)
client.new(
    key="stack",
    structure_family=StructureFamily.array,
    data_sources=[
        DataSource(
            management=Management.external,
            mimetype=OME_ZARR_MIMETYPE,
            structure_family=StructureFamily.array,
            structure=adapter.structure(),
            assets=[Asset(data_uri=uri, is_directory=True, parameter="data_uri")],
        )
    ],
    metadata=dict(adapter.metadata()),
    specs=[],
)

The URI may name the image group or its full-resolution array; both read the same way.

Writing runs with TiledWriter

bluesky-tiled-plugins' TiledWriter registers each data key of a run from its StreamResource document, with a structure computed from the documents: the number of rows times the shape of each. A detector writing a multidimensional OME-Zarr store frame by frame describes a stack of frames, which is not the shape of the store, and the node cannot be read. Registering the consolidator this package provides makes TiledWriter store the image as the store holds it, with its shape, chunks and axis names:

from bluesky import RunEngine
from bluesky_tiled_plugins import TiledWriter
from tiled.client import from_uri

from ome_tiled.bluesky import register_consolidator

register_consolidator()
RE = RunEngine()
RE.subscribe(TiledWriter(from_uri("http://localhost:8000", api_key="...")))

The detector's StreamResource gives application/x-ome-zarr as the mimetype and the store, or its image, as the URI. The server needs OmeZarrAdapter registered for that mimetype, as above.

What it reads

• NGFF 0.4 and 0.5 images and label images, validated with yaozarrs. The axes, with their types and units, are under axes in the node's metadata.
• A Zarr group holding several such images, each presented as its own array.
• The full-resolution level only. Pyramids read at level 0.

Anything else is served as tiled's Zarr adapter serves it, with a log line saying why: other NGFF layouts such as bioformats2raw series, plates, wells and label groups, and any group whose NGFF metadata fails validation. Validation is strict, so a file that breaks the NGFF specification, for example a dataset without coordinateTransformations, reads as plain Zarr rather than as an image.

Axes of a custom kind, such as a scan pattern, keep their names too. NGFF orders axes as time, then channel or custom, then space, so a file that puts a custom axis after the spatial ones fails validation and reads as plain Zarr.

More

The tiled documentation explains adapters, mimetypes and detection hooks in more detail: Serve Files with Custom Formats.

License

Apache License 2.0. See LICENSE.