Load an image, or start measuring on the blank canvas.
Click once to place the first point, click again to place the second.
Load an image, click once to place the first endpoint, move the mouse to preview the measurement, and click again to place the second endpoint.
Click and drag anywhere on the image to pan. Use the mouse wheel to zoom in and out around the cursor.
Click a measurement label to set its calibrated length. Click the calibration display in the toolbar to edit units per pixel directly.
This is a James Stanley project. All the coding was done by GPT-5.4-codex.
Source: github.com/jes/image-measurer