WorkshopGirl / local photo tools
Photo Measurement Lab.
A known reference turns a workshop photograph into a useful estimate. Mark dimensions, compare shapes and keep a record of your work.
Images stay in this browser tab. No uploads, accounts or saved browser records. Export your work before closing or reloading.
Or drop an image anywhere in the lab. JPEG, PNG, supported WebP · 20 MiB · 32 megapixels · 12,000 px per edge. Working image: at most 4 megapixels / 2,400 px per edge.
No image open.
Open a photograph to begin.
Open a photo.
Calibrate a reference.
Measure your work.
Wheel / pinch to zoom. Choose Pan to drag the view. In Select, drag handles or lines; arrow keys move a selected point (Shift = 10 px). Enter finishes a path or applies a reference; Escape cancels; Delete removes the selection; Ctrl/⌘ Z undoes (Shift redoes). Visual point identification requires sight; exact coordinate controls and a text list are available below.
No unfinished points.
Exact image coordinates / keyboard placement
Coordinates use the full working image, independent of the visible zoom. The origin is its top left.
Edit selected item
Measurements & annotations
No measurements yet. Calibrate, choose a tool, then place points.
PNG contains the complete working image, independent of zoom, with labels and dimension values. JSON v1 contains geometry, original oriented coordinates, scale, measurements, units and notes. It excludes image bytes. Downloads are local; this tool cannot restore a session from JSON.
A useful estimate starts with a good photograph.
- Keep the camera square to a flat surface. Place an accurate ruler or known rectangle next to the object in the same plane. Fill the frame, keep it sharp, and avoid wide-angle distortion.
- Use a long reference, with visible endpoints. Zoom to place points and repeat placements to check the spread. For example, ±1 pixel at each endpoint on a 100-pixel reference can already contribute about 2% scale uncertainty; displayed decimal places do not prove accuracy.
- For perspective correction, supply both real dimensions of a rectangle. Correction cannot recover depth, lens distortion, curved surfaces, hidden edges or lost image detail. Distances and areas only apply to that plane; circles should be measured after correction when the plane is tilted.
- Angles need three points, with the vertex second. Polyline and area need Finish path. A circle uses the center and radius point, not automatic detection or a fit to blurred edges.
- Add labels and notes, then export PNG and JSON. Cross-check critical cuts, tolerances and safety-related dimensions with a physical instrument. This is observational documentation, not certified metrology.
Privacy: image decode, correction, drawing and export happen locally. The site still loads normal site assets. This tab holds the image in memory; closing, restoring or replacing it releases processing resources. Reloading loses your edits.