Supported Formats: JPG, PNG, TIFF, BMP, PDF.
Tip: If importing a PDF with multiple pages, Engauge will ask you which page or image to digitize.

Step 2: The Axis Wizard (Critical Step)

Once the image is loaded, the Axis Wizard will pop up automatically. You need to click on 3 known points on the graph to define the coordinate system.

Where to Click:

Click 1: Origin

Usually the bottom-left corner (0,0).

Click 2: X-Axis End

The far right of the X-axis (e.g., 100, 0).

Click 3: Y-Axis Top

The top of the Y-axis (e.g., 0, 100).

After clicking the points on the image, enter their actual graph values (e.g., 0, 10, 100) into the input boxes that appear.

💡 Pro Tip: Handling Tilted Scans

Is your scanned image rotated or crooked? Don’t worry. Engauge automatically corrects the geometry based on the 3 axis points you set. You don’t need to rotate the image in Photoshop beforehand!

2 Automation

Stop Clicking Manually

Engauge features powerful algorithms to trace lines and detect points automatically. The secret lies in removing the “noise” first.

The Secret Step: Color Filtering

Before you use the magic wand, you must tell Engauge what represents “data” and what is just “background grid lines.”

Go to the Settings menu and select Filter.
Adjust the Foreground Color sliders to match your curve (e.g., if your curve is blue, isolate the blue range).
You should see the grid lines disappear in the preview window, leaving only the curve visible.

Goal: Remove the Grid

Before

→

After

Choose Your Automation Tool

🪄 Segment Fill Tool

Best for: Continuous Lines

Simply click once on the curve. Engauge will automatically “flood fill” the line until it hits a break or an intersection.

Tip: If it stops at an intersection, just click the next segment to continue.

🎯 Point Match Tool

Best for: Scatter Plots

Draw a box around a group of markers (circles, triangles, squares). Engauge will find the center of each marker and place a point there.

Tip: Great for noisy data where lines aren’t connected.

💥

Why did the tool select the whole screen?

If you click “Segment Fill” and the entire image gets selected, it means you didn’t filter the background properly (Step 1). The software sees the white background as connected to your curve. Go back to Settings > Filter and ensure grid lines are removed from the preview.

3 Advanced

Logarithmic & Polar Axes

Real-world scientific data isn’t always linear. Engauge Digitizer is built to handle complex coordinate systems including semi-log, log-log, and polar plots.

Handling Log Scales (Semi-Log / Log-Log)

Many scientific graphs (e.g., Bode plots, chemical concentration) use a logarithmic scale on the X or Y axis. If you treat them as linear, your extracted data will be mathematically wrong.

How to configure:

Step 1: Define Axis Points

Set your 3 axis points as usual. Enter the exponent values if the label says 10², or the raw number (100) if written out.

Step 2: Change Scale Type

Go to Settings > Coordinates. Under “X Axis” or “Y Axis”, change the dropdown from Linear to Log.

⚠️ Important: When digitizing log scales, ensure your axis points cover at least one full decade (e.g., from 10 to 100) for maximum accuracy.

Digitizing Polar Plots

For antenna radiation patterns or microphone sensitivity graphs, you are working with Radius (r) and Angle (θ), not X and Y.

Switch Mode: Before clicking any points, go to Settings > Coordinates and select Polar.
Set Origin: Click the exact center of the circle as your first axis point.
Define Perimeter: Set points on the outer ring to define the scale of the Radius and the orientation of the Angle (usually 0° is right, 90° is up).

🧹

Grid Line Interference?

If Engauge is accidentally tracing the background grid lines instead of your data curve, try the “Discretize” filter. This forces the image into black-and-white mode, making it easier to separate the thick data curve from thin, faint grid lines.

? Help Center

Troubleshooting & FAQ

Encountering an error? Here are the solutions to the most common installation and usage problems.

💻 Error: “VCRUNTIME140.dll” or “MSVCP140.dll” was not found

The Problem: Your Windows computer is missing the standard C++ runtime libraries required to run Qt applications like Engauge. This is very common on fresh Windows installations.

The Fix: Download and install the Visual C++ Redistributable (x64) directly from Microsoft.
Download Official Fix from Microsoft →

🍎 Error: “Engauge Digitizer cannot be opened because the developer cannot be verified”

The Problem: macOS blocks apps that aren’t signed with an expensive Apple developer certificate. Since Engauge is free open-source software, it triggers this warning.

The Fix:

Locate the Engauge app in your Applications folder.
Right-click (or Control-click) on the icon.
Select Open from the menu.
Click Open again in the popup dialog. You only need to do this once.

Q: My CSV export has weird decimal points.

If you are in Europe, your Excel might expect commas (,) instead of dots (.) for decimals. In Engauge, go to Settings > Export Format and check your “Decimal Separator” settings before exporting.

Q: Can I digitize multiple lines in one image?

Yes. Go to the Curves List (View > Curves) and click “Add New Curve”. You can name them differently (e.g., “Dataset A”, “Dataset B”) and they will be exported as separate columns in the CSV file.

Q: How do I import a PDF?

Just drag the PDF file into Engauge. A dialog will appear asking you to select which page you want to import, and allow you to crop the specific graph area.

Q: I placed a point wrongly. How to delete?

Switch to the Select Tool (Arrow icon). Click on the bad point to highlight it, then press the Delete key on your keyboard.

Master Engauge Digitizer

Getting Started

Automatic Tracing

Advanced Topics

Troubleshooting

Importing & Setting Axes

Step 1: Import Your Image