Plot Digitizer: Plot Digitizer is a useful program for extracting data from a linear, semi-log, or log-log plot.

Using an optical scanner, create a Bitmap or JPEG  image of the plot and open the image file in Plot Digitizer. Then, after calibration, you can extract the data values by merely clicking on the data points.

Plot Digitizer screenshot

Calibration Window

Download Plot Digitizer.

plotdigitizer SHA-1 Hash Value:
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  • A zoom window aides you in clicking on precisely the point you are interested in.
  • Automatically corrects for the rotation of the image you're analyzing as well as the non-orthogonality of the axes.
  • Any 3 non-collinear points can be used for calibration. (Calibration points do not need to be on the axes.)
  • Save your progress at any time in a "project" file.
  • Label the calibration points you have selected. (Labels can be toggled on and off.)
  • Label the points you're digitizing on the calibrated image. (Labels can be toggled on and off.)
  • Export the calibrated image (showing the point labels) to a bmp or jpeg file.
  • Export data to an ASCII, an MS Excel or an MS Word file
  • Download "How Plot Digitizer's calibration works". (PDF)

Department of Physics
University of South Alabama
Mobile, AL 36688