VectorGraph converts any chart image or PDF into precise, exportable numerical data. Supports 4 chart categories, 9 export formats, live data inspection, and built-in math & calculus tools — all free, browser-based, with no server uploads.
VectorGraph is built to handle nearly any data visualization format.
XY plots, multi-curve, continuous data, scatter plots with markers.
Vertical/horizontal bars, grouped/stacked bar series, frequency histograms.
Polar coordinate charts, radar/spider/web charts, multi-axis radial data.
Segment angle extraction, donut charts, compound pie-of-pie charts.
Most charts are fully extracted in under 5 minutes.
Accepted formats: PNG, JPG, JPEG, BMP, WebP, SVG, and PDF (multi-page — select any page via visual page picker modal). Also supports direct clipboard paste. Drag-and-drop or click-to-browse.
Image Enhancement tab controls: Brightness, Contrast, Fine Rotation/Deskew slider (±45°). Advanced filters: Grayscale, Sharpen, Invert Colors, Denoise, Binarize (Pure B&W with threshold). Gridline Removal using morphological operations (auto-detects grid color). CLAHE for low-contrast scientific charts. Crop tool for trimming chart borders. All enhancements are non-destructive — original image is preserved.
Open the CALIBRATE tab. Place calibration pins at known coordinate points on the chart. Supports 2-point (simple) and 4-point (skewed/rotated charts) calibration modes. Enter the real numeric values, click Apply. Affine transformation (Cramer's Rule) maps every pixel to real coordinates. Supported coordinate systems: Linear X/Y, Log-Log, Semi-Log (X or Y), Polar/Radar (angular), Pie (segment-angle mode). Axis name and unit labeling. Apple Pencil / stylus support for precision pin placement.
In the CURVES tab, add one curve/series per data set. For bar/pie/radar charts, groups are created automatically with color matching. Use the Eyedropper (Color Pick tool) to click on the target curve to capture its color. Configure tolerance. Live pixel match count shows how many pixels match your color selection. The Dominant Color Palette analyzer shows the top colors in the chart.
Choose your extraction tool (see Extraction Tools section). Click Extract. Processing runs in a background WebAssembly (OpenCV.js) worker — the UI stays fully responsive. A progress indicator shows live status. You can cancel at any time.
Open the Data Inspector: view your extracted (X, Y) data in an editable table with sorting and row selection. The live chart preview (ECharts) re-renders on every edit. Apply Math & Calculus tools: smoothing, peak detection, polynomial fitting, derivative, area integration. Save results as new curves or overwrite existing ones.
9 export formats available (see Export section). All exports are generated instantly in-browser — no server upload, no waiting.
VectorGraph's Pixel Harvest module provides 5 named extraction tools plus advanced algorithms, collectively covering all chart types and complexity levels.
Automatically traces continuous line curves with no manual interaction. Best for: smooth line charts, spectral data, time series. Uses multiple underlying algorithms (averaging, mask tracing, Hessian ridge following). Full parameter control: strip width, merge window, gap bridging, color tolerance.
Click anywhere on the chart to capture a target color. All pixels within a configurable color-distance tolerance are identified and traced. Live pixel match count updates in real-time as you adjust tolerance. Supports auto-tolerance detection.
Draw a Region of Interest mask to restrict extraction to a specific area of the chart. Mask types: Rectangle, Polygon, Freehand brush, Ellipse. Undo/redo mask edits. Full-canvas select. Mask overlay renders in real-time. Essential for overlapping curves and complex multi-series charts.
Samples at fixed horizontal X intervals across the chart with configurable step size, bounds, and line width. Supports cubic spline interpolation between sampled points for sub-pixel smoothness. Also supports user-supplied custom X values for targeted sampling.
One-click extraction for bar charts and histograms. Automatically detects bar boundaries, heights, and groups. Extracts all bars in the series with a single click. Produces well-formatted data with groups, labels, and colors matching the uploaded chart exactly.
(Accessible in advanced mode) — Blob Detector (scatter plot markers), Polar Wedge Scan (radar/polar radial sweep), Frangi Ridge Filter (vessel-like structures in noisy charts), K-Means Color Cluster (complex multi-color backgrounds).
After extraction, open the Data Inspector panel for full visibility and control over your extracted data.
View extracted (X,Y) pairs. Inline cell editing, row selection, column sorting, delete rows, add points manually.
ECharts-powered chart that re-renders instantly on every data edit. See your data exactly as it will be exported.
Configure line type (Straight/Smooth), markers, bar labels, pie label mode (%, values, or both), polygon fill for radar, border display.
Zoom in/out, pan, reset view, export chart as PNG or SVG directly from the inspector.
For radar/spider charts: assign custom text labels to each spoke axis.
Trigger any of the 9 export formats directly from the Data Inspector. Pie Parent Selector included for pie-of-pie charts.
No need to export data just to run basic analysis. The Math tab provides chart-type-specific mathematical tools applied directly to your extracted data.
VectorGraph exports in more formats than any other free browser-based graph digitizer. Choose the right format for your workflow.
| Format | Description | Best For |
|---|---|---|
| Excel (.xlsx) ⭐ | Multi-sheet workbook: Combined summary sheet + individual sheet per curve, embedded chart preview (well-formatted) | Excel workflows, reports, multi-curve comparison |
| CSV | Comma-separated values, UTF-8 encoded | Python, R, spreadsheets, data pipelines |
| JSON | Structured array of coordinate objects | Web apps, JavaScript, APIs |
| XML | Standard XML document | Enterprise systems, legacy integrations |
| Format | Description | Best For |
|---|---|---|
| PNG | High-DPI chart image (respects selected aspect ratio) | Presentations, reports, documents |
| SVG | Scalable vector chart | Web embedding, print, scaling |
| PDF Report | Paginated professional report with embedded chart | Client deliverables, documentation |
| PDF Combined | Source image + extracted chart + data table in one PDF | Full audit trail, archiving |
| DXF | AutoCAD-compatible vector format | CAD software, engineering drawings |
Note: PNG, SVG, PDF, and DXF exports all respect a configurable aspect ratio (Free, 16:9, 4:3, 1:1).
VectorGraph includes precision alignment features to ensure accurate extraction even on complex or imperfect charts.
Pins snap to detected chart lines and gridline intersections for precise axis calibration. Reduces human error when placing calibration points.
For radar/polar charts: spoke angles snap to configurable angular grid (e.g., every 15°, 30°, 45°). Ensures accurate spoke placement even on non-standard radar charts.
The Pixel Harvest (X-Step Interpolated) tool applies cubic spline interpolation between sampled points, producing smooth sub-pixel-accurate curves from regularly sampled data.
Color distance tolerance is normalized against image statistics. Auto-tolerance mode automatically sets the optimal tolerance value for clean extraction.
VectorGraph is built for real workflows — not just one-off conversions.
VectorGraph includes a comprehensive interactive guide built directly into the app — no external documentation needed.
Sub-pixel accuracy on clean, high-resolution charts. On high-quality images, typically within ±0.3–0.5% of the full axis range. Accuracy depends on source image quality. Low-contrast, blurry, or heavily compressed images produce lower accuracy. Image enhancement tools (brightness, contrast, sharpen, CLAHE) can significantly improve results on difficult sources.
Four categories: (1) Line & Scatter charts, (2) Bar charts & Histograms (vertical, horizontal, grouped, stacked), (3) Polar & Radar/Spider charts, (4) Pie, Donut & Pie-of-Pie charts. Additionally supports logarithmic axes (log-log, semi-log), dual-axis charts, and skewed/rotated images.
Each curve is extracted separately. Add one curve in the CURVES tab per data series. Use the Eyedropper to select each curve's color, or draw an ROI mask to isolate a specific curve from overlapping ones. All curves are stored in the same project and exported together — Excel exports each curve on its own sheet.
PNG, JPG, JPEG, BMP, WebP, SVG, and PDF (multi-page — select any specific page via visual page picker).
9 formats: Excel (XLSX with multi-sheet + embedded chart previews), CSV, JSON, XML, PNG (chart image), SVG (vector chart), PDF Report, PDF Combined (image + chart + data), DXF (AutoCAD CAD format).
Yes. After the page loads, VectorGraph works with no internet connection. All processing — image analysis, calibration, extraction, export — runs locally in your browser using WebAssembly (OpenCV.js). Your data never leaves your machine.
Yes. VectorGraph supports Linear, Log-Log (both axes logarithmic), and Semi-Log (one axis logarithmic) calibration. Select the scale type in the CALIBRATE tab before placing pins.
The Excel (.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 together. An embedded chart preview image is included in the workbook.
Yes. Open the Data Inspector to view your extracted points in an editable table. You can modify any (X,Y) value inline, delete rows, add new points manually, and apply math transformations (smoothing, derivative, polynomial fit). The live chart preview updates instantly on every edit.
For post-extraction analysis without leaving VectorGraph. Features include: Moving Average smoothing, Polynomial Fitting (degree 1–8), Peak Detection (with prominence control), dy/dx Derivative computation, Area integration (∫), Descriptive Statistics (mean, std dev, range), Bar Statistics (sum, median, mode, Pareto), and Delta/Change analysis. Each result can be saved as a new curve or used to overwrite the original.
Select the Bar/Histogram project type, calibrate the Y-axis, then use the Auto Bar tool. VectorGraph automatically detects bar boundaries and heights. For grouped or stacked bars, each color group is extracted separately and organized into labeled groups that match the original chart's colors exactly.
Yes. Select Polar/Radar chart type, configure the number of spokes and their labels in the CALIBRATE tab, then use the Polar Wedge Scan tool to sweep radially from the center and extract values at each spoke. Results include per-spoke values with the original chart's colors.
In the IMAGE tab, enable Gridline Removal. VectorGraph uses morphological operations to detect and remove horizontal and vertical gridlines. Use the auto-detect grid color button for automatic detection, or manually set the grid color. The original image is preserved — gridline removal is non-destructive.
Yes, completely free. No account, no subscription, no usage limits, no data upload. All features including advanced algorithms, CAD export, and PDF reports are free.
Yes. VectorGraph is optimized for Apple iPad with full Apple Pencil support. Pressure-sensitive stylus input is supported for precise calibration pin placement and ROI mask drawing. Works on all modern mobile browsers.
VectorGraph auto-saves every change to your browser's IndexedDB storage. No manual save needed. You can also export a backup file of all your projects to keep a portable copy, and restore from that backup file on any browser.
Free. No account. No installation. Runs entirely in your browser.
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