Import a figure, crop the ROI, correct rotation/perspective, optionally calibrate axes, and export a
rectified PNG + JSON mapping.
Input Data
Source:—
(Requires HTTPS)
Original size
—
Working stage
—
Zoom
—
Cursor
—
Workspace Mode
Pan: drag background • Zoom: mouse wheel • Precision: arrow keys (Shift = 10px). In Warp mode, drag
corners labeled TL/TR/BR/BL. In Calibrate mode, click points on the rectified image.
Crop (ROI)
ROI (orig px)
—
Deskew (Rotate)
Rotation is applied after crop and before perspective warp.
Perspective Warp
Pre-warp size
—
Rectified size
—
Drag TL/TR/BR/BL points. Use arrow keys to nudge the active point (Shift = 10px). Hover shows pixel and
(if calibrated) data coords.
Axis Calibration (Optional)
X points
—
Y points
—
Calibration is applied on the rectified image. Switch to Warp mode and Apply Warp first.
Then switch to Calibrate and click points.
Export
Exports are designed to feed the downstream digitizer tool, but are useful standalone.
The accuracy of everything here is set by where you clicked, not by the maths.
Corner placement and calibration points are yours, and a few pixels of error in either
propagates straight through the rectification into every value read off the result. The
transform assumes the original figure was a flat plane photographed or scanned without
lens distortion, which a page from a bound book is not. Validate against a known reference
value on the figure before trusting any measurement taken from it. Runs entirely in your
browser, with no server processing or storage. Provided as-is, without warranty, and used
at your own risk. The site-wide notice carries
the full terms.