Graph digitizer comparison – 16 ways to digitize your data (updated)

progress-01Although pdf files are the current standard for the dissemination of scientific knowledge, the format comes with several, well known, drawbacks. An important limitation is the difficulty to re-use the data embedded in graphs and plots. Even with the advent of “enhanced” html versions of articles, data is still most often represented with images, which makes it difficult to extract the raw numbers. A few initiatives from publishers now ask researchers to submit their data along with their manuscript. But for the millions of paper already published, a number of different software solutions can help you digitize the data from plots and graphs.

Digitize your graphs and plots

All the tools presented below follow a similar process to convert bars graphs, scatter plots, and line plots into a series of numbers.

 1. Open a graph

1270668950Depending on the software, the graph can be imported directly from a .pdf file, or will first have te be converted to an image format (jpg, bmp, png, gif…). The image can be obtained through the html version of the paper, or by taking a screenshot of the pdf file (on Mac use command-Shift-4; on Windows use the print screen button or by use the Snipping Tool; on Linux use the Take Screenshot application). When saving your screenshot, be aware of what file format your software accepts.

 2. Set the scale

TWebPlotDigitizerhe software will ask you to define the axis and set the scale. This is how it will define the coordinates of each point. The more precise you are while doing this, the better your results will be. Most software allow for distorted axis (not perfectly perpendicular). And remember to indicate wether the graph is in log scale. (the image to the left taken from WebPlotDigitizer).

 3. Digitize the data points

WebPlotDigitizerYou then need to digitize the points or lines. Depending on the software, this step is going to be more or less automated. Most often, you are asked to, at least approximatively, indicate where the points or lines are located. Some fully manual will ask you to draw over the points or line in order to digitize the data.

 4. Export the data

export-3Finally, copy and export your data into the format that is most convenient to you. Some software include additional acquisition data analysis functionalities. But most often this is done by simply pasting a table of coordinates in your favorite data processing software.


Comparative study of graph digitizer softwares

We have put together a comparison table of 16 graph digitizer software. There might be others out there worth mentioning. Please do not hesitate to comment and we will add them to the list.

 plateformcostautomatic detectionfiles supportedpost aquisition analysisyear
Dagra: Digitize graphical dataWindows$49.95yes~ all image formatsno2012
DataThiefWindows, MacOS, Unix$25noJPG, PNG, GIFno2006
dcsDigitiserWindows$423yes~ all image formatsyes2015
DigitizeItWindows, MacOS, Unix$49yes~ all image formatsno2014
EngaugeWindows, MacOS, UnixFreeyes~ all image formatsno2015
g3dataWindowsFreeno~ all image formatsno2011
Get DataWindowsFreeyes~ all image formatsno2013
Graph ClickMacOSFreeyes~ all image formatsno2014
im2graphWindows, LinuxFreeyes~ all image formatsno2015
Graph Data ExtractorWindowsFreenoBMP, JPG, TIF, GIF, and PNGno2011
Image J pluginWindows, MacOS, UnixFreeno~ all image formatsno2014
MATLAB tool (Grabit)Windows, MacOS, UnixFreenoBMP, JPG, TIF, GIF, PNGyes2007
Plot DigitizerWindows, MacOS, UnixFreenoJPG, PNG, GIFno2014
Un-Scan itWindows, MacOS$345yes~ all image formatsyes2014
WebPlotDigitzerWeb basedFreeyes~ all image formats no2014
WinDig Data digitizerWindowsFreenoBMPno1994
xyExtract Graph DigitizerWindows$45noBMPno2011

So what solution is best for you? Well, as often, it depends. For most cases, using the browser-based WebPlotDigitzer will be the most convenient. It handles many types of graphs and plots, while being free. It does not require any installation, and is compatible with all platforms. You might want to consider however that because WebPlotDigitizer is a web-based tool, the current software version number is unknown, which makes it hard to reference the analysis you will have done with precision and can get in the way of reproducibility.

For the more demanding situations, Un-Scan it might help, since comes with the longest list of functionalities. It is also the most expensive solution listed here.

Also, if you are a R user, you will find tutorials online on how R can help you extract data from graphs, and a paper describing a dedicated R package developed by Timothée Poisot.

Please comment and share your experience with these tools! Many thanks to David LeBauer for his insights and comments.

Update (30th of July 2015). I have added to the list im2graph

12 thoughts on “Graph digitizer comparison – 16 ways to digitize your data (updated)

  1. The list does not show “dcsDigitiser Graph Digitizer,” which is developed by me myself and fully automatic – just one click to obtain hundreds or thoudands data points. It also includes calculation of area size enclosed by freely defined data points, curve fitting and math tools. Regards, Jinan

  2. Good time of a day.
    Thank you for your post – it helped a lot.
    But maybe you can give me one more advice. Is there any program which can automatically digitase many similar images? They all have same axes, and graphs in more or less the same place.
    I’ve done something close to it using “GetData Graph Digitizer” and click-recorder scripts, but it feels… not so smart option.
    I tried to check all available programs, but some of them dont have full functional in trials and I cant check it (and I havent tried R, because I dont know it good enough, but I can work through it, if my task is possible). Or maybe I have overlooked some advanced functions.

    (I can’t attach images here 🙁 )

    Thank you,

  3. Answering my own question (which hasn’t shown up yet) about how to get data out of PDFs directly, rather than converting to bitmaps, here is what I found:

    Some seriously virtuoso mathematica there… but the basic idea should be followable I think.

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