Measurement

ROI

Shift+R shows or hides ROI mode. Hiding ROI mode keeps the session's ROIs.

Draw on the canvas to measure a region. The default shape is a circle.

Shapes: circle, rectangle, freehand, flood fill. Switch via the colorbar controls.

For flood fill, [ / ] adjusts tolerance.

Click an existing ROI to select it. Delete / Backspace removes it.

Stats opens the ROI manager: rename/delete ROIs, adjust extent, export CSV, or export a label mask.

N exports the active ROI or segmentation mask as .npy.

Ruler

u — enter ruler mode. Click two points to measure pixel distance. Press u again to exit.

Pixel info

Hover over the image to see coordinates and value reflected on the colorbar.

Click the colorbar to copy that value to the clipboard.

i — toggle a persistent hover tooltip that follows the cursor.

I — show a data info overlay: shape, dtype, size, file path.

Export

Key	Action
s	Open save options (screenshot PNG, GIF, .npy export)
e	Copy a reusable URL to clipboard

Screenshots download as PNG. GIF saves an animation along the current slice dimension. .npy export saves the current slice.

Caveat

ArrayView works across six invocation environments (CLI, Python script, Jupyter, Julia, VS Code, SSH). Not every feature has been verified in every mode. If something behaves differently than documented, check the remote page for environment-specific notes or open an issue.