How VectorGraph Works —
Extract Data from Any Chart
VectorGraph converts any chart image or PDF into precise, exportable numerical data. 8 extraction tools, 4 chart types, 9 export formats, Scholar & Advanced modes — all free, offline, running entirely in your browser.
4 Chart Categories — One Tool
VectorGraph handles every major scientific and business data visualization format.
Line & Scatter Charts
XY plots, multi-curve continuous data, scatter plots with markers. Supports linear, log-log, and semi-log axes.
Bar & Histograms
Vertical and horizontal bars, grouped and stacked series, frequency histograms with class-interval export.
Polar & Radar/Spider
Polar coordinate charts, radar/spider/web charts with configurable spokes, multi-axis radial data.
Pie, Donut & Pie-of-Pie
Segment angle extraction, donut inner-radius control, compound pie-of-pie sub-chart assignments.
From Image to Data — 7 Steps
Most charts are fully extracted in under 5 minutes.
Upload Chart Image
PNG, JPG, WebP, SVG, or PDF. Multi-page PDF with visual page picker. Drag-and-drop or clipboard paste (Ctrl+V).
Enhance the Image
Adjust brightness, contrast, rotation (±45° deskew), apply filters (Binarize, Grayscale, Sharpen), crop to region, and non-destructive gridline removal.
Calibrate Axes
Place pins on known coordinate values. Supports 2-point and 4-point affine mapping. Linear, log-log, semi-log, polar, and pie modes.
Add Series
Create one curve per data series. Use Color-Pick to click on any target curve, or the Dominant Color analyzer to identify the top chart colors.
Run Extraction
Pick your tool — Auto Trace, Color-Pick, Pixel Harvest, Auto Bar, Region Select, or manual point-click. Processing runs off the main thread.
Inspect & Refine
Edit data in the Data Inspector table, validate in the live ECharts preview, and apply Math tools (smoothing, peak detection, polynomial fit).
Export Data
9 formats: Excel, CSV, JSON, XML, PNG, SVG, PDF Report, PDF Combined, and DXF (AutoCAD). Generated instantly in-browser.
8 Tools for Every Chart Type
Scholar Mode includes the core extraction tools. Advanced Mode unlocks all 8.
Automatically follows continuous line curves using Frangi Ridge detection. Best for clean, solid line charts.
Click on a color in the chart. All matching pixels are isolated using LAB color space distance. Auto-tolerance supported.
Draw a bounding box to isolate a specific chart area. The dominant path inside the region is extracted automatically.
Manually place data nodes with exact precision. Nodes connect sequentially and can be adjusted with the Node Editor.
Draw rough strokes over a line. On release, Chaikin subdivision snaps your stroke into a smooth analytic spline.
Drag any existing node to shift its exact coordinates. Select a node and press Delete to remove it. Drag-to-delete gesture available.
Deep ROI-masked extraction with multiple algorithms: Averaging Window, Blob Detector, Zhang-Suen Skeleton, K-Means Cluster.
Single-click bar and histogram extraction. Detects bar boundaries, heights, and groups them by color automatically.
Tip: Start with Auto Trace for clean line charts. Use Color-Pick + Region Select for multi-curve charts. Use Auto Bar for bar/histogram charts. Pixel Harvest is best for noisy or overlapping data in Advanced Mode.
Scholar Mode vs. Advanced Mode
Switch modes anytime via the toggle in the header. Your data and projects are never affected.
Scholar Mode
Clean, distraction-free interface for first-time users and straightforward extractions. Hides advanced-only tools.
Advanced Mode
All Scholar tools plus two powerful advanced-only algorithms for complex, noisy, or multi-color charts.
Live Preview & Full Editing Control
Open the bottom panel after extraction for complete visibility and control over your data.
Editable Data Table
Inline cell editing, multi-row selection, column sorting. Add, delete, or modify any (X, Y) value. Copy entire table to clipboard.
Live ECharts Preview
Interactive chart re-renders instantly on every edit. Pan, zoom, and reset. Export chart directly as PNG or SVG.
Chart Settings
Toggle smooth vs. straight lines, point markers, bar labels, pie label mode (%, values), polygon fill for radar charts.
Auto-Normalization
Sorts points left-to-right, removes multi-valued segments, and uses RDP algorithm to optimally reduce dense point clouds.
Measurement Tools
Distance Ruler, Angle Measurement (3-point), and Area/Perimeter for enclosed regions — all overlay-rendered on the canvas.
Export from Inspector
Trigger any of the 9 export formats directly from the Data Inspector. Pie parent selector included for pie-of-pie charts.
Math & Calculus — Built Right In
Post-extraction analysis without leaving VectorGraph. Chart-type-specific tools applied directly to your data.
Curve Fitting
- Curve Fitting — 7 models (Linear, Exp, Log, Sinusoidal, Power, Quadratic, Cubic) with Auto-Select Best Fit.
- Equation Export — Copy ready-to-run Python/NumPy or Excel formulas.
- Residuals & Uncertainty — View residuals plot and ±σ confidence bands.
- Smoothing — Moving average with configurable window.
Calculus
- dy/dx Derivative — Numerical derivative of any extracted curve
- ∫ Area Integration — Trapezoidal rule area under curve
- True Polar Area — Geometric polar area for radar/polar data
Statistics & Peak Detection
- Peak Detection — Local maxima & minima with configurable prominence
- Descriptive Stats — Count, range, mean, std dev, area
- Copy results to clipboard
Bar Chart Math
- Bar Statistics — Sum, Mean, Median, Mode, Min, Max, Std Dev
- Pareto / Cumulative Sum — One-click Pareto chart generation
- Delta Analysis — Sequential or group-comparison change values
- Gaussian Fit — Bell curve distribution fitting for histograms
9 Export Formats — Data, Charts & CAD
Choose the right format for your workflow. All exports are generated instantly in-browser — no uploads, no waiting.
Data Formats
| Format | Description | Best For |
|---|---|---|
| XLSX | Multi-sheet workbook: summary sheet + one sheet per curve, with headers, metadata, and embedded chart preview | Excel workflows, reports, multi-curve comparison |
| CSV | UTF-8 comma-separated values | Python, R, MATLAB, spreadsheets, data pipelines |
| JSON | Structured coordinate array with metadata | Web apps, JavaScript, REST APIs |
| XML | Standard XML data document | Enterprise systems, legacy integrations |
Chart & Vector Formats
| Format | Description | Best For |
|---|---|---|
| PNG | High-DPI chart image with configurable aspect ratio (Free, 16:9, 4:3, 1:1) | Presentations, reports, documents |
| SVG | Scalable vector chart | Web embedding, print, infinite scaling |
| PDF Report | Professional paginated report with embedded chart visualization and data table | Client deliverables, documentation |
| PDF Combined | Source image + extracted chart + data table in a single PDF | Full audit trail, archival records |
| DXF | AutoCAD-compatible vector format | CAD software, engineering drawings |
Excel XLSX Advantage: VectorGraph's XLSX export generates a fully formatted multi-sheet workbook — summary chart sheet, individual data sheets per curve with curve names and units, and an embedded chart preview image. No other free browser-based digitizer produces Excel files this structured.
Keyboard Shortcuts
Speed up your extraction workflow with these tool shortcuts. Hover over any toolbar button to see its shortcut key.
Multi-Project Workspaces & Auto-Save
Built for real workflows — not just one-off conversions.
- Unlimited Projects — Each with its own image, calibration, curves, and settings. Switch instantly.
- Workspace Folders — Organize into named folders. Drag-and-drop projects between folders.
- Auto-Save — Every change persisted instantly to IndexedDB. No manual save needed.
- Backup & Restore — Export all project data as a ZIP. Restore on any browser, never lose your work.
- PWA Installable — Install VectorGraph to your desktop or mobile home screen via the browser prompt. Works offline.
- WebGL Accelerated — Konva hardware acceleration handles 50,000+ data points without stutter.
- Privacy First — All data stays in your browser. No uploads, no cloud sync, no tracking.
- Apple Pencil Support — Pressure-sensitive stylus input on iPad for precision calibration and ROI drawing.
Built-In Guide & Live Tour
No external documentation needed — every guide is built directly into the app.
- Interactive Guide — 20+ categorized topics covering every tool with live animated mock-UIs and "Try it now" jump buttons.
- Live Tour — Step-by-step interactive walkthrough launched from the header. Highlights each UI element in context.
- Onboarding Tour — 12-step guided tour for first-time users. Runs automatically on first launch.
- Mode Selection Modal — One-time prompt after onboarding to choose Scholar or Advanced mode based on your experience level.
- Live Guide Overlay — Context-sensitive help panel that follows your active tool with relevant tips and procedure steps.
- Swipe & Keyboard Navigation — Guide supports horizontal swipe gestures on mobile and keyboard arrow navigation.
Frequently Asked Questions
Sub-pixel accuracy on clean, high-resolution charts — typically within ±0.3–0.5% of the full axis range. Accuracy depends on image quality. Use the image enhancement tools (brightness, contrast, sharpen) to improve results on difficult sources.
Four categories: (1) Line & Scatter charts, (2) Bar & Histograms (vertical, horizontal, grouped, stacked), (3) Polar & Radar/Spider charts, (4) Pie, Donut & Pie-of-Pie charts. Also supports logarithmic axes, dual-axis charts, and skewed/rotated images.
Extract each curve separately. Add one series per curve in the Curves tab. Use Color-Pick to target each curve's color, or draw an ROI mask with Region Select to isolate overlapping segments. All curves are stored in the same project and exported together.
PNG, JPG, JPEG, BMP, WebP, SVG, and PDF (multi-page — select any page via the visual page picker modal). Also supports direct clipboard paste (Ctrl+V / Cmd+V).
Yes. After the first load, VectorGraph works with no internet connection. All processing — image analysis, calibration, extraction, export — runs locally in your browser using WebAssembly. Your data never leaves your machine.
Yes. VectorGraph supports Linear, Log-Log (both axes logarithmic), and Semi-Log (one axis logarithmic, base-10 or base-e) calibration. Select the scale type in the Calibrate tab before placing pins.
The XLSX export generates a multi-sheet workbook. Each extracted curve gets its own formatted sheet with column headers, data values, and curve metadata. A combined summary sheet shows all curves. An embedded chart preview image is included in the workbook.
Scholar Mode shows only the core extraction tools for a clean, focused experience — ideal for new users or straightforward charts. Advanced Mode unlocks all tools including Pixel Harvest. Switch modes anytime via the toggle in the header.
Yes. Open the Data Inspector to view your extracted points in an editable table. Modify any (X,Y) value inline, delete rows, add points manually, and apply math transformations. The live chart preview updates instantly on every edit.
In the Image tab, enable Gridline Removal. VectorGraph uses morphological operations to detect and erase horizontal and vertical gridlines. Use the auto-detect color button or set the grid color manually. The original image is always preserved.
Yes, completely free. No account, no subscription, no usage limits, no uploads. All features — including advanced algorithms, CAD export, PDF reports, and Excel export — are free forever.
Yes. VectorGraph is optimized for iPad with full Apple Pencil support. Pressure-sensitive stylus input is available for calibration pin placement, ROI mask drawing, and freehand tracing.
Ready to extract your first chart?
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