Engineering Plot Digitizer

Extract numerical data from scanned or image-based engineering plots.

Upload a plot image

PNG, JPG, or other browser-supported image format. Your image is processed locally and is not uploaded or stored by EngMathTools.

Choose image

1. Upload plot

Current

Choose a plot image to begin.

PNG, JPG, or another browser-supported image format.

2. Calibrate axes

Locked

Click the plot corners in order: lower left, lower right, upper right, upper left.

X min

X max

Y min

Y max

Use the actual graph boundaries, not the image edge. Logarithmic limits must be greater than zero.

3. Digitize curve

Locked

Click points along the curve you want to digitize.

Start with breakpoints or slope changes, then add intermediate points only where needed.

Cursor X—

Cursor Y—

Upload an image to begin.

#	X	Y

How plot digitization works

The image is calibrated by matching known plot corners to real axis values. After calibration, each click is transformed from image coordinates into engineering coordinates based on the selected axis scale.

For log-log plots, pixel position maps linearly to the logarithm of each axis value. This makes the tool useful for extracting data from legacy shock response spectra, PSD curves, fatigue plots, material-property curves, and other engineering figures that only exist as images or scans.

Recommended workflow

Use the actual plot boundaries for calibration rather than the edge of the image. Click distinct breakpoints or changes in slope first, then add intermediate points only where needed to capture the curve shape.

Data privacy and security

Your plot image is processed locally in your browser. EngMathTools does not upload, transmit, or store the image on a server. The plot and digitized points remain only in the current browser session and are discarded when the page is closed or refreshed.