How to convert a scanned graph into real data

Have you ever had to pull data from an image of a graph? Maybe a supplier faxed you a 1940s era scan of the variable viscosity of peanut butter. Or, maybe your 401k administrator just sent you a glossy brochure showing historic portfolio performance (yay) and recent changes (boo).

Or, maybe you need to pull data off a chart like this one:

You could get out a ruler and start measuring just like you did in high school. Or, you could download an incredibly useful (and totally free) software tool to do the work for you.

Engauge Digitizer converts any image of a graph into numbers. The image can come from a scanner, digital camera, or screenshot. The tool lets you mark key numeric locations on the image, define the axes, and select the desired points/curves. Then, it magically converts everything into x/y point data that you can bring into Microsoft Excel for re-use.

Enjoy!

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66 comments

  1. Thanks for posting this! I regularly use charts from spec. sheets and this is going to save me a TON of time and effort.

    1. Wow, my pleasure! Glad it helped.

  2. Jeff Waters · ·

    Hi Jeff, great to hear! Is it enough to win me a Bose noise canceling headset? (Just kidding)

  3. Jeff Waters · ·

    Hi Jeff, great to hear! Is it enough to win me a Bose noise canceling headset? (Just kidding)

  4. thank you for this, so… much thanks… i cant say in words for this help…. thank you …

  5. thank you for this, so… much thanks… i cant say in words for this help…. thank you …

  6. Thanks for posting this! I regularly use charts from spec. sheets and this is going to save me a TON of time and effort.

    1. Wow, my pleasure! Glad it helped.

  7. Superb…i was blindly searching for this type of software without positive hope..But for my surprize, I got it!!!!! Thanks a ton…:)

  8. Glad it helped, thanks for stopping by!

  9. Great tool. Thanks!
    Does anybody know how to convert the output data into uniform intervals?
    I’ve generated coordinates with random intervals but I need data that goes 1,2,3….

    1. Paul Lane · ·

      This is most easily done on a spreadsheet using formulas for linear interpolation. When I need to put data on the same time base, I use the slope and intercept formulas in Excel to do the trick.

  10. Good question… I have no idea!
    Please post here if you find an answer.

  11. thnx

      1. grammar guru · ·

        you’re

      2. Oops! Your absolutely right. Dang, I did it again.

  12. Nifty little software. Saving me a ton of time!

  13. Glad you like it, AJ.

  14. Thank you very much … It save me a lot of time .
    Thank u from Saudi Arabia 🙂

  15.  My pleasure!

  16. Mick Stevens56 · ·

    OMG, fantastic !!

    1. Mick, I believe you are the first person to type “OMG” on my blog! Thanks.

  17. Mehrda Hojjati · ·

    tnx dude. does anyone have any idea about getting an excel output out of it?

  18. tnx dude. does anyone have any idea about getting an excel output out of it?

  19. I think you just save out a .csv and open that in excel, right?

  20. This saved me so much time today! This is perfect for extracting data from spec sheets. And yes, you can export it as a .csv and open it an excel.

  21. Hi Jeff, I’ve never heard of Engauge Digitizer until today.  I’ve been using the Plot Digitizer program for several years and I think its interface is better.  I wanted to get your thoughts on it.  
    http://www.southalabama.edu/physics/software/plotdigitizer.htm

    1. Very cool FlowJoe, thanks!

  22. Christoph · ·

    Interesting, I have designed my own using some math software but as with all digitizer programs there is user input required.  And some fuzzy logic, as with your graph above, the y-axis is not exactly perpendicular so the values of the data points extracted will be, of course, only a fair approximation. 

    1. Yep– but the nature of going from analog to digital will always be a bit fuzzy.

    2. Flow Joe · ·

      Any good image editing program can be used to adjust the image to make the axes aligned correctly. I use the alignment tool in Paint Shop Pro.

      Also you must remember that this software tool is a step up from using a pencil and a straight edge, such as a ruler, and can be faster. The user’s job is not done after the data is collected from the software; sounds vaguely familiar to using an analysis program. One must review the numbers and consider the significant digits used in obtaining the numbers as well as the process in how the original data was measured with instruments.

  23. Ibrahim Maged · ·

    thanks

  24. Does anyone know if this program can be used for non-linear sets of data? I have lots of data that’s very volatile, and whenever I hit print screen, copy to paint, and import the image, Engauge Digitizer will give me the axis, but not the curve. Where am I going wrong? 

    1. Flow Joe · ·

      Try the Plot Digitizer program, I find that it’s very easy to use, never tried the Engauge software so don’t know how to compare.
      Here’s the link to download: http://www.southalabama.edu/physics/software/plotdigitizer.htm

      Also, MS Paint is no good at images.  A pay for software that’s ready good at snagging images, some editing and saving to different formats is Snag It by Techsmith.  And a free one that I like to use for dropping copied images, cropping and saving to almost any format is Irfanview (just google the name)… does some editing but is limited… cropping is really easy, just window and then Ctrl+Y.

      1. ImanHejazi · ·

        Thanks

    2. Not sure, Hal. Please post here when you get a solution. Thanks!

  25. Atefeh Aryana · ·

    thanks

  26. Atefeh Aryana · ·

    can you help me to convert a picture to a garph?

  27. Flow Joe · ·

    Atefeh, I would first try it out for yourself by downloading the program and then going to Help > User’s Guide.
    Here’s the link again to my preferred program: http://www.southalabama.edu/physics/software/plotdigitizer.htm

    1. Thanks Joe! Agreed.
      I still need to check out that Plot Digitizer. 
      Think you could record a video overview of it and feature it on my blog?

      1. Hello there, I like to know if this or any other tool you might know off would allow me to implement this from an image capture via a smartphone camera. Basically I like any feedback that would allow me to convert pics from smartphone camera to an excel data base. Any help will be much appreciated.

        Contact info
        mac_ maya@ hotmail.com

      2. Hi Israel,
        Well, you could certainly take a picture with your smartphone, transfer the image to your PC, and run through Engauge. I don’t know of an app that would do it all on your smartphone, though.

      3. Mac_maya · ·

        Thank you Jeff for your input. I would have thought that given the current bar code readers and scanner technology out there that there would be the same for scanning an image and turning it into pieces of data.

    2. awesome and its working

  28. does it work on ecg graph ?

    1. Good question… it’s free, so have a try at it and let me know.

      1. How many points we can extract from curve using this software?

        i mean curve is discretion ?

      2. Good question… it’s free, so have a try at it and let me know 😉

  29. ImanHejazi · ·

    Majicccc, Wonderful

    1. Great, glad you found it useful!

  30. THANK YOU THANK YOU THANK YOU !
    I’ve been looking for a free tool as such for quite some time.

    1. Your welcome! If you run across other useful tools for engineers, please drop me a line.

  31. You can also use the free software, im2graph (http://www.im2graph.co.il) to convert graphs to data, available on Linux and Windows (Mac soon). Disclaimer: I wrote the software.
    – Shai

    1. Hi Shai, thanks for sharing! Looks great!

    2. Hi Shai, your tool looks great. I just posted a mention of it on Linkedin. Please feel free to connect with me there if you like: http://www.linkedin.com/in/jeffupfront

      1. Hello Jeff, I currently do not have a LinkedIn profile (used to, a decade ago but not any longer). Maybe I’ll reupdate it 😉 Thanks! Shai

  32. Chua Lee Suan Dr. · ·

    Hi Jeff, I just come across your software after searching online for a few days on how to convert picture and graph into data. I have tried to download the software, but received an error message “The program cannot start because Qt3supportd4.dll is missing form your computer.” Could you please help me?

    1. Hi Dr. Suan. I apologize, but I don’t have anything to do with developing this tool. Just found it useful many years ago. It’s possible that it isn’t being developed anymore?

      There are a couple of other good options listed by others in the comment section on this thread.

      FlowJoe just recommend one that looks great and is completely web-based. I haven’t tried it, but you may want to see if it fits your needs:

      http://arohatgi.info/WebPlotDigitizer/app/

      1. Chua Lee Suan Dr. · ·

        Hi Jeff, Thank you so much. Appreciate also the help from Flow Joe. The WebPlotDigitizer is really helpful. Please allow me to ask another question. If I have converted all the graphs into numerical data and stored as my “database”, and then I would like to upload and match an unknown graph to the most similar data from the existing database graphically or numerically. Do you have any idea about it? Thanks in advance….

  33. I’ve recently started using a Google Chrome app called “WebPlotDigitizer.” http://arohatgi.info/WebPlotDigitizer/app/
    When you learn how to use it (just watch a few video tutorials), it does a great job of automatically pulling the data off charts. There is also a manual mode. I recommend trying it out for yourself.

    1. Thanks FlowJoe… that looks great! I notice it also can push you to something called “Plotly” Have you tried that as well?

      1. FlowJoe · ·

        Jeff, I used Plot.ly for the first time when I was testing out the WebPlotDigitizer (also for 1st time). I could verify that the data was read correctly, so I only got surface deep into Plot.ly. The visualizations are not ugly; take a look at samples. Here are the benefits of Plot.ly stated on their blog ( http://blog.plot.ly/post/89402845747/a-graph-is-a-graph-is-a-graph ):
        1. Any (computer) language: Plotly lets you make graphs with any language or file type – all in one place. We also translate your visualizations into executable code in other languages.
        2. Universality for project teams
        3. Collaboration among team
        4. Efficiency: GUI or code or both

      2. FlowJoe · ·

        Forgot to write that Plot.ly is based in Montreal.

  34. Is v6 yet prepared as an .exe file? I cannot find it.