Labelme keyboard shortcuts: work with both hands

Watch an annotation session and the cursor tells only half the story. The other hand is making the decisions.

One hand points at the image. The other rests near A and D, ready to move between files, start a shape, fix a label, or clear the canvas. Once those movements become familiar, you spend less time looking for controls and more time looking at the image.

You do not need to memorize a wall of shortcuts. Start with one loop.

On macOS, use Cmd wherever this guide shows Ctrl, Option for Alt, Fn+Delete for Delete, and the key labeled Delete for Backspace. For example, Ctrl+Delete becomes Cmd+Fn+Delete; Settings and the Meta+H point-removal binding are written out separately in the reference.

Learn one review loop#

1. Press Ctrl+U to open an image directory, then Ctrl+F to fit the first image to the window.
2. Inspect the image. Press T when you need to hide every shape and check the pixels underneath.
3. Fix what is wrong. Ctrl+E edits a label. Ctrl+J returns to edit mode. The arrow keys move selected shapes by five pixels. Delete removes a selected shape.
4. Press D for the next image. Press A if you need to go back.

Auto-save is on by default, so each edit is written before you move on. Your right hand can stay on the mouse while your left handles the repeated decisions.

This is the part worth practicing. The full reference can wait until a specific action sends you looking for it.

The combinations worth understanding#

Copy once or keep copying

D opens the next image. Ctrl+Shift+D opens it and carries the current annotations with you. The same distinction applies in reverse with A and Ctrl+Shift+A.

That modified shortcut is useful when two neighboring frames are similar. For a whole run of related images, Ctrl+P turns on Keep Previous Annotation until you turn it off again.

Ctrl+Z follows the work

While drawing, Ctrl+Z removes the last point you placed. In edit mode, it undoes the last shape addition or edit. A bad polygon vertex costs one keystroke; you do not have to throw away the shape.

Press Enter or Space to finish a closeable shape, and Esc to cancel the shape in progress. Hold Alt if you need to place a polygon point near its first point without snapping the cursor closed.

T gives you the image back

Dense polygons can hide a missed edge or object. T toggles all shapes without deleting them, so you can compare the annotation with the raw image and press T again to bring the overlay back.

The arrow keys move five pixels

In edit mode, select one or more shapes and use the arrow keys for a fixed five-pixel move. It is a controlled adjustment, not a one-pixel nudge. Use the mouse when you need finer placement.

Choose what deserves a binding#

Polygon and rectangle creation have defaults: Ctrl+N and Ctrl+R. Oriented rectangle, circle, line, point, and linestrip creation are unbound until you assign them.

You can change the configurable actions under shortcuts in Labelme's default configuration. App and canvas controls such as Enter, Esc, the arrow keys, the Settings shortcut, and keyboard-and-mouse combinations are fixed rather than part of that mapping.

Learn the defaults that occur in your own work. A polygon annotator needs Ctrl+N; a bounding-box review pass may never use it. The useful set is the one your hands stop having to search for.

The starter guide covers the full annotation flow. The packaged Labelme app is available from the download page.

Printable quick reference#

This reference covers every non-empty default in the current shortcuts configuration, plus the fixed app and canvas controls used during annotation.

Files and navigation

Ctrl+Delete removes the annotation file after confirmation. It does not delete the image.

Drawing

Oriented rectangle, circle, line, point, and linestrip creation have configurable entries but no default key binding. AI-Points and AI-Box do not have configurable shortcut entries.

Editing

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