3.7. "image-label" metadata

[dstansby]

Groups containing the image-label dictionary represent an image segmentation in which each unique pixel value represents a separate segmented object. image-label groups MUST also contain multiscales metadata and the two "datasets" series MUST have the same number of entries.

The image-label dictionary SHOULD contain a colors key whose value MUST be a list of JSON objects describing the unique label values. Each color object MUST contain the label-value key whose value MUST be an integer specifying the pixel value for that label. It MAY contain an rgba key whose value MUST be an array of four integers between 0 and 255 [uint8, uint8, uint8, uint8] specifying the label color as RGBA. All the values under the label-value key MUST be unique. Clients who choose to not throw an error SHOULD ignore all except the last entry.

Some implementations MAY represent overlapping labels by using a specially assigned value, for example the highest integer available in the pixel range.

The image-label dictionary MAY contain a properties key whose value MUST be a list of JSON objects which also describes the unique label values. Each property object MUST contain the label-value key whose value MUST be an integer specifying the pixel value for that label. Additionally, an arbitrary number of key-value pairs MAY be present for each label value denoting associated metadata. Not all label values must share the same key-value pairs within the properties list.

The image-label dictionary MAY contain a source key whose value MUST be a JSON object containing information on the image the label is associated with. If included, it MAY include a key image whose value MUST be a string specifying the relative path to a Zarr image group. The default value is "../../" since most labels are stored under a subgroup named "labels/" (see above).

The image-label dictionary SHOULD contain a version key whose value MUST be a string specifying the version of the image-label specification.

https://ngff.openmicroscopy.org/0.4/index.html#label-md