Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


An OMERO.web app for visualizing images in OMERO.

Also see


  • OMERO 5.6.0 or newer.


In order to build you need:

  • nodejs version 6.x
  • npm version equal or greater to 3.0!
  • apache ant

To build an uncompressed version, run:

$ npm run debug

To build an uglified version, run:

$ npm run prod

All builds will build into the build directory and deploy to the plugin directory which can then be used like any Django plugin.


Instructions on how to add the OMERO.iviewer app to your installed OMERO.web apps can be found in the OMERO.iviewer README.


A guide to using OMERO.iviewer can be found on


OMERO limits the size of Z-projections to reduce load on the server. The limit is defined as the number of bytes of raw pixel data in a Z-stack and the OMERO.server default is equivalent to 1024 * 1024 * 256 bytes. For example, a single-channel 8-bit image (1 byte per pixel) of XYZ size 1024 * 1024 * 256 is equal to the default threshold.

To double the limit, use:

$ omero config set omero.pixeldata.max_projection_bytes 536870912

If you wish to set a threshold for iviewer that is lower than for the server:

$ omero config set omero.web.iviewer.max_projection_bytes 268435456

NB: Z-projection is not supported for tiled images in OMERO (Images larger than 2048 * 2048 pixels per plane are tiled in iviewer).

OMERO uses Spectrum Color Picker for selecting ROI colors. The roi_color_palette option allows you to specify a grid of colors for users to choose for ROIs. Define rows with brackets, and use commas to separate values. By default, only the first color of each row is shown. A full grid is shown when the default color picker is hidden (see below) To define a color palette use:

$ omero config set omero.web.iviewer.roi_color_palette "[rgb(0,255,0)],[darkred,red,pink],[#0000FF]"

To hide the default color picker (and show a grid for the color palette), set show_palette_only to true You must define a palette and each row can display 4 colors:

$ omero config set omero.web.iviewer.show_palette_only true

Known issues

For images with many channels (greater than approximately 30 channels), saving of rendering settings fails due to the length of the request string. See #321. A work-around is to configure gunicorn to allow longer request strings. For example, to double the allowed limit:

omero config set omero.web.wsgi_args ' --limit-request-line 8192'

When a palette is defined it will try to use the first value as the default ROI color. Currently only rgb() vals are correctly parsed. If you try to use hex or a css name it will default to black You can look up a conversion to rgb and set that as your first value for a workaround

Supported URLs

If you have configured OMERO.iviewer as your default viewer (see install) then double-clicking an Image in OMERO.web will open OMERO.iviewer as the OMERO.web viewer, passing the current Dataset if the Image is in a Dataset:


You use the OMERO.webclient's 'Open with...' menu to open multiple selected Images or a Dataset or a Well in OMERO.iviewer directly:


Other query parameters can be used to set the rendering settings for the first image, including channels in the form of index|start:end$color:

?c=1|100:600$00FF00,-2|0:1500$FF0000      # Channel -2 is off

You can also specify the rendering Model (greyscale or color) and Z-Projection (maximum intensity or normal):

?m=g            # g for greyscale, c for color
?p=intmax       # intmax for Maximum intensity projection, normal for no projection

The Z and/or T plane, X/Y center position and zoom can be defined by:

?z=10&t=20          # can use z or t on their own
?x=500&y=400        # need to specify center with x AND y
?zm=100             # percent


It is recommended to use the webpack dev-server to build and serve OMERO.iviewer as this will re-compile automatically when files are saved.

To build the bundle and start the webpack dev-server (localhost:8080):

$ npm run dev

You will also need an OMERO.web install with omero_iviewer installed. To add your project to your local OMERO.web install, add the project to your PYTHONPATH and add to omero.web.apps

$ export PYTHONPATH=$PYTHONPATH:/path/to/omero-iviewer/plugin
$ omero config append omero.web.apps '"omero_iviewer"'


The webpack dev-server config expects a local OMERO server at http://localhost (default port 80). Should the server instance use a different port you will need to modify all proxy target entries in

devServer: {
    proxy: {
        '/iviewer/**': {
            target: 'http://localhost:your_port'
        '/api/**': {
            target: 'http://localhost:your_port'
        }, ...

If you want to bind the webpack dev server to a port other than 8080 you will need to change its port property in

devServer: {
    port: your_port

The initial data type (e.g. image, dataset, well) and its respective ID can be set/changed in index-dev.html:

        <link rel="stylesheet" type="text/css" href="build/css/all.min.css" />

        <script type="text/javascript">
            // modify according to your needs
            // in particular: choose an existing id !
            window.INITIAL_REQUEST_PARAMS = {
                    'VERSION': "DEV_SERVER",
                    'WEB_API_BASE': 'api/v0/',
                    //'IMAGES': "1",
                    'DATASET': "1",
                    //'WELL': "1"


To run all tests, run:

$ ant unit-tests

For more details on testing, see


A high-level description of the OMERO.iviewer application can be found at

To build the JavaScript code documentation in build/docs, run:

$ npm run docs


The OMERO.iviewer's internal image viewer is based on OpenLayers,

For details on how to run and test this viewer independently of the OMERO.iviewer, see

More details

More detailed resources on how to create a web app and development setup can be found at:

  1. CreateApp
  2. Deployment