HED Tools Online

What is HED?

HED (Hierarchical Event Descriptors) is a framework for systematically describing both laboratory and real-world events. HED tags are comma-separated path strings. The goal of HED is to describe precisely the nature of the events of interest occurring in an experiment using a common structured vocabulary and standardized tools. The HED framework has been developed for neurological imaging data (e.g., EEG, MEG, iEEG, fMRI), physiological (e.g., ECG, EMG, GSR) as well as multimodal experiment (e.g., mobile brain/body imaging). HED has been adopted as part of the BIDS (https://bids.neuroimaging.io) standard for brain imaging.

HED online tools summary

The following table summarizes the available online tools. The tools are organized around the types of data that the tools handle. The Actions refer to the types of actions that can be performed on the data through the online tools. Each action is linked to its corresponding documentation to provide additional information.

Data type
(linked to form>
(linked to docs)
Events Validate Validate HED in an events file and its sidecar.
Assemble annotations Append a HED_assembled column to an events file.
Generate sidecar template Create a sidecar template from an events file.
Execute remodel script Execute JSON script of HED remodeling commands.
Sidecars Validate Validate HED in a BIDS JSON sidecar.
Convert to long Convert HED tags in a sidecar to full paths.
Convert to short Convert HED tags in a sidecar to single tags.
Extract HED spreadsheet Create a 4-column spreadsheet from HED in a sidecar.
Merge HED spreadsheet Merge HED from spreadsheet into a JSON sidecar.
Spreadsheets Validate Validate HED in a spreadsheet (.xlsx or .tsv).
Convert to long Convert HED tags in a spreadsheet to full paths.
Convert to short Convert HED tags in a spreadsheet to single tags.
Strings Validate Validate a HED string.
Convert to long Convert a HED string to full paths.
Convert to short Convert a HED string to single tags.
Schemas Validate Validate a HED schema.
Convert schema Convert a HED schema to other format.
Compare HED schemas Show differences between two HED schemas.

Events files are tabular (tab-separated) files. The first row of an events file contains column names. Each subsequent row corresponds to an event marker at a specified time in the corresponding data file.

Sidecars are JSON text files containing metadata. Sidecars follow the requirements of the BIDS (Brain Imaging Data Structure) standard.

Spreadsheets contain tabular data in either as an Excel .xslx or as a tab-separated text file. They are used for convenience in assigning HED tags to event codes.

Strings refer to HED annotations, which are entered as strings for quick checks for validity or conversion.

Schemes refer to HED schema vocabularies, which may be either in .mediawiki or .xml format. These tools are used by schema developers creating the HED vocabularies and are not of interest to annotators or analysts.

More detailed help on using these online tools is available at: HED online tools

HED REST services

The HED online tools are also available as callable web services. More detailed help on calling these services is available at: HED RESTful services Downloadable examples of calling these services from a MATLAB program can be found at: GitHub MATLAB examples

Where to find out more?