🎯 Centerline Extraction Tool

Choose File

Upload the source image or PDF you want to trace. Drag-and-drop onto the upload area works the same as using the file picker.

Image Opacity

Fades the background image without changing the traced paths. Lower values make the magenta and blue overlays easier to inspect.

Single Viewer

The main viewer shows everything in one place: the image, the raw magenta centerlines, and the blue fitted export overlay when optimisation is enabled.

Crop

Turn Crop on from the viewer header to place an editable crop frame immediately. If you are already zoomed into a region, the crop starts from the current view.

Zoom To Crop

Centers and zooms the viewer on the active crop box. Useful for checking a crop region before running detection or export.

Reset View

Restores the default viewer framing after panning or zooming. Turning Crop off also clears the crop and resets the image view.

Dark Threshold

Controls how dark a pixel must be before it is treated as part of a line. Raise it to ignore faint background texture; lower it to recover lighter strokes.

Normalization Mode

Controls whether upload preprocessing evens out lighting and contrast before detection. Use Auto for most images, Force On for uneven scans, and Force Off when the source is already clean.

Normalization Sensitivity

Sets how aggressively Auto mode decides to normalize. Higher sensitivity normalizes more images, which helps difficult scans but can flatten already-good artwork.

Min Path Length

Filters out short detected paths before optimization. Raise it to drop dots and tiny fragments; lower it only when genuine short strokes are being lost.

Simplify

Prune vertices to reduce node count. Usually unnecessary if you plan to enable Path Optimisation below.

Auto-Tune

Samples the current image or crop region and suggests threshold and minimum path length settings. Use it when the input quality changes from file to file.

Show Magenta Paths

Shows or hides the raw magenta centerlines in the main detection view while you compare them against the fitted blue output.

Enable Optimisation

Turns on smoothing and fitted SVG export. When it is off, the viewer and download stay with the raw magenta extraction only (use LightBurn Optimisation to smooth and simplify).

Source Smoothing

Smooths the detected path before SVG fitting. Raise it to reduce staircase jitter; lower it if corners start rounding more than you want.

Enable Curve Fitting

Allows the fitted export to use cubic curves. It is only active when optimisation is enabled.

Cubic Fit Tolerance

Controls how tightly cubic segments follow the smoothed path. Lower values preserve more detail; higher values reduce segment count and file size.

Force Orthogonal Paths As Lines

Keeps axis-aligned and corner-like features as straight line segments instead of curves. Useful for technical drawings and rectilinear geometry.

Auto-Tune

Starts a focused search for better threshold and minimum path length values using the current image or crop region.

Auto Detection Tuning Review

Auto-Tune can open a review panel that previews threshold and minimum-length changes on sampled busy regions before the full image run continues. While review is active, the Apply button appears next to Auto-Tune for quick confirmation.

Apply

Accepts the shown tuning values and continues with full-image processing. It appears to the right of Auto-Tune while guided tuning review is active.

Download SVG

Exports the current result from the results panel. With optimisation off, the SVG matches the raw magenta extraction. With optimisation on, the export includes the fitted blue output.