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Annotate a slide

This tutorial takes you from an open slide to a saved annotation you can find, edit, and download. It uses the Annotations and Draw panels in HistomicsUI.

Before you start

  • You can open a slide in the viewer. If not, start with Upload and view your first slide.
  • You have write access to the image item. Without it, the New button and the Draw panel are hidden.
  • You know which style group you should use. If your study defines groups, ask the study owner. Otherwise use the default group.

1. Open the slide

Open the image item. HistomicsUI loads the image in the viewer with the Annotations panel on the right. The Draw panel appears when you have annotation access.

2. Create an annotation

  1. In the Annotations panel, select New (the button with the plus icon). The keyboard shortcut is the space bar.
  2. In the Create annotation dialog, enter a Name. The default is Annotation <date and time>; replace it with something meaningful, such as Tumor region 1.
  3. Optionally add a Description.
  4. Leave Show on first load off unless the annotation should be visible to everyone when the image opens.
  5. Select Save.

The new annotation appears in the Annotations panel and becomes the active annotation. The Draw panel title shows its name.

3. Choose a style group

In the Draw panel, open the style-group dropdown and select a group. The colors and line width come from that group.

To create or change groups, select the gear button beside the dropdown. The style-group editor lets you create, rename, restyle, import, export, and set the default group. See Annotation style groups.

4. Draw an element

Select a tool and draw on the image:

Tool Shortcut What to do
Rectangle r Drag from one corner to the opposite corner
Polygon p Click each vertex; close the shape to finish
Ellipse i Drag to set the ellipse extent
Circle c Drag from the center outward
Line l Drag from start to end
Point o Click once
Brush b Paint a freehand stroke; set square or circle and a size in the brush dropdown

For rectangles and ellipses, the small dropdown beside the tool offers Unconstrained, Fixed Aspect Ratio, and Fixed Size with width and height fields.

The element is added to the active annotation and saved automatically. The spinner beside the Annotations title means a save is in progress.

5. Verify the result

  • The element appears in the image with the group's colors.
  • The annotation is listed in the Annotations panel under its style group.
  • The panel's element count includes the new element.
  • The eye icon toggles the annotation's visibility.

If the panel is collapsed, expand it. If the annotation is hidden, select the eye icon or press a to show all annotations.

6. Edit or delete the element

Right-click the element. The context menu offers:

  • Remove group — clears the element's group.
  • The available style groups — move the element to another group.
  • Edit Shape — adjust the geometry (e).
  • Edit Properties — edit element-level values such as the label.
  • Delete — remove the element.

To edit the annotation document itself, use the gear icon in the Annotations panel. The Edit annotation dialog has Name, Description, Show on first load, and a style section for point, line, and polygon elements.

7. Download a copy

In the Annotations panel, select the download icon beside the annotation. The browser downloads the annotation's JSON document. Use this for a backup, for an analysis script, or to attach the annotation to a paper trail.

Troubleshooting

The symptom-first index covers style groups, autosave failures, export, and annotations that are invisible after sharing: Troubleshooting and FAQ: annotation.

Symptom Likely cause Fix
There is no New button You do not have write access to the item, or you are not signed in Sign in. Ask the item owner for write access if it is still missing.
There is no Draw panel The image is not open in the viewer, or you lack annotation access Open the image item itself, not a folder listing. Check your access.
The annotation does not appear in the list The panel is collapsed or the annotation is hidden Expand Annotations; press a to show all.
The element uses the wrong color The active style group is different from the one you expected Select the group in the Draw dropdown and redraw, or right-click the element and choose the correct group.
The Draw panel offers only a few groups The annotation has an allowed_groups restriction Use one of the listed groups, or edit the annotation metadata if you own it. See Annotation style groups.
Changes do not stick The save failed or your session expired Check the save spinner and the browser console; sign in again and retry.

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Source and version

The control labels, dialog fields, and shortcuts were checked against the HistomicsUI web client at commit 75a9be6 on 2026-11-01. They were not click-tested on a writable slide because this documentation slice had no writable test account. If your deployment differs, the source is authoritative. See Annotation basics for the underlying model.