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Jiro Doke


17 Mar 2005 (Updated )

Extract (pick out) data points off image files.

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GRABIT Extracts data points from an image file.

GRABIT starts a GUI program for extracting data from an image file. It is capable of reading in BMP, JPG, TIF, GIF, and PNG files (anything that is readable by IMREAD). Multiple data sets can be extracted from a single image file, and the data is saved as an n-by-2 matrix variable in the workspace. It can also be renamed and saved as a MAT file.

Following steps should be taken:
   1. Load the image file.
   2. Calibrate axes dimensions. You will be prompted to select 4 points on the image.
   3. Grab points by clicking on points. Right-click to delete a point. Image can be zoomed during this stage.
   4. Multiple data sets will remain in memory so long as the GUI is open. Variables can be renamed, saved to file, or edited in Array Editor.

Panning is achieved by clicking and dragging on the image. In addition to using the zoom button, there are keyboard shortcuts for zooming:
 <shift> - center view
 <a> - zoom in
 <b> - zoom out
 <space> - reset view

This code will also work for extracting data points from a tilted or a skewed image (even upside-down or mirrored). The calibration stage ensures that the imperfect orientation or quality of the image is accounted for.

The types of files that will most likely work are BMP, JPG, TIF, GIF (up to 8-bit), and PNG files. Basically, any format supported by the IMREAD is accepted.

GRABIT(FILENAME) will start the GUI program and open the image file FILENAME.
Type GRABIT('-sample') to load a sample image.

Created in MATLABĀ® R13. Tested up to R2006a


This file inspired Interactivemouse and Smi Prom.

MATLAB release MATLAB 6.5 (R13)
Other requirements Tested up to R2006b
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Comments and Ratings (61)
11 Jan 2015 Bikash


It is working fine. Nice work.

18 Dec 2014 Ole


How does it work with log axis ?
Thank you.

Comment only
02 Dec 2014 Nikhil


21 Oct 2014 Nitin


31 Aug 2014 Abhishek Anchal

Abhishek Anchal

Nice work Jiro. Liked it. Very useful for me.

03 Apr 2014 Amit


05 Mar 2014 Keith Lindsay

Keith Lindsay

17 Dec 2013 Andrew Stamps

Andrew Stamps

This has been a very useful submission for me. One minor improvement that I could suggest is an option to recalibrate the x-axis and y-axis independently. I think that would be great for plots with multiple y axes.

05 Dec 2013 Yukyung


Won't work in 2013b though

27 Jul 2013 Roberto Herrera

Roberto Herrera

18 Jun 2013 Yuji Zhang

Yuji Zhang

Works so well! Thank you for your contribution Jiro~

Suggestion: automatic recognize curve (if possible)

17 Mar 2013 Adrian Lara-Quintanilla

Adrian Lara-Quintanilla

10 Mar 2013 arnold


thanks Jiro, great tool. If you find the time, why don't you go and put in a way to select a continuous color (a line) for instance. This would make clicking along a closed plot unecessary. What do you think ;)

06 Feb 2013 Danny Sale

Danny Sale

Worked perfectly for me. This is one of the best implementations of a plot digitizer I have ever used. Thanks for sharing your excellent work!

09 Jul 2012 Francesco


Great tool!
Does exit an updated version to deal with logarithmic axes?
Or maybe some one could give me some clue to implement it in the code... thanks

23 Feb 2012 Zhen Chen

Zhen Chen

14 Feb 2012 Luke


22 Dec 2011 Ahmed Ali

Ahmed Ali

Many thanks for you, you have solved a very complex problem for me

12 Jul 2011 James Herman

James Herman

01 Jul 2011 mike


Thanks for the great tool. I'm currently trying to adapt it a little bit for my use, and bit of help would be appreciated.

I have a bunch of images from which I plan to grab data. However, they only have y axis reference points, so I can't calibrate them properly. The x-axis is on the same scale as the y-axis, so what I want to do is force the origins of both axes to be at the same location. Then I can force the horizontal distance (on screen) between Xo and Xmax to be the same as the vertical distance between Yo and Ymax. However, I don't really understand how the locations of the calibration points are stored and used, so I'm having trouble.

11 May 2011 Oscar


It is very helpful, veru well done

Comment only
25 Mar 2011 quadro1327


very nice tool!

17 Feb 2011 Thomas


06 Dec 2010 Nassim Khaled

Nassim Khaled

10 Nov 2010 Whitney


There are several versions of this type of GUI on the exchange, but this is by far the best one. It incorporates all of the stuff that the other guys are missing, plus the interface is very easy to use. I especially like that it can handle skewed images from really old scanned papers.

11 Oct 2010 Matthew



03 Jun 2010 Enrico


Nice Gui, but miss an automatic curve recognition. I'm also using reverseplot
(, which has this feature, but a slightly inferior gui.

12 Jan 2010 Ram Lakshmi

Ram Lakshmi


Thanks for this nice tool.
Instead of point, can I get an area by marking a particular region in the bit map.

Comment only
17 Sep 2009 Torsten Vogel

Torsten Vogel

02 Mar 2009 Donat-Pierre Luigi

Donat-Pierre Luigi

This a great application. I would have one request. Would it be possible to calibrate to the image size, with origin at top left max Y at bottom-left and max X at top-right. It is very basic and not as general as the current calibration procedure using 4points.
I am having issues with zoom and ginput to get the coordinate of a point in an image to change the coordinate system to that point later on in pixel and physical units. Thanks.

23 Feb 2009 Brian


A very useful application.

26 May 2008 a c


04 Apr 2008 ghgf ghf  
26 Mar 2008 Sigmund As

Excellent tool - best one of these I've used so far. Log axes? No problem, just type in the exponent as the calibration values.

* Ask the user if the data should be adjusted if the user recalibrates after grabbing.
* If the scan is not perfectly horizontal it would be nice to have two adjustment points for each xmin, xmax, ymin, and ymax - i.e. support for rotated coordinate transformation.

23 Dec 2007 Mikkel Pedersen

Super tool!

Need the capability to use log-axes though.

30 Oct 2007 Lorenzo Luini

This is one of the best and most useful tool I found here: really compliments!

19 Oct 2007 Jhon Gonzalez


Is it possible that in the preview box shows the position calibrated and the corresponding pixel?

I plan to use it to calibrate a video to follow a laser spot

16 Oct 2007 Iomsn Egenson

This program is ingenious. It is extremely small, easy to use and yet so useful that it makes it the ultimate grab tool.

11 Oct 2007 Amandine Cagnioncle

This script is a lot better than Datathief which I formerly used. It makes extracting data from figures easier and faster!

06 Sep 2007 Avi Pal

Does not work. from the first line itself it says unexpected matlab operator..
please help. i think its not identifying 3d
i am using matlab (R14)

Comment only
06 Sep 2007 Avi Pal

Does not work. from the first line itself it says unexpected matlab operator..
please help.
i am using matlab (R14)

Comment only

for the last six month i am trying to extract the data from the image file. Now i got it. this is very well work for me and all (those who are working Scientific data processing).

21 Feb 2007 Jean-Luc Dellis

Thanks a lot. Good Job.

09 Feb 2007 Eduard van der Zwan

This is something I was looking for. Thank You. Tip: wouldn't it be nice to extract data point form graphs with logaritmic axes?

07 Feb 2007 Pankaj Porwal

Just loved it. Very good interface also.

12 Jan 2007 Hector Mancha

Very usefull,

18 Nov 2006 Cong Le  
10 Nov 2006 Lars Sundstrom

Extremely useful. Thank you very much for sharing.

03 Aug 2006 Nick Peters

Excellent tool. Thanks for posting.

02 May 2006 Seis Errs

very useful tool. Thanks a lot.

30 Mar 2006 John Terry

excellence! I am waiting for the next version which can deal with logarithmic axis. Good luck!

30 Mar 2006 iman satria  
02 Mar 2006 Jiro Doke

I have uploaded an improved version. It has a better zooming feature (also zoomable during calibration) and a click-n-drag panning feature. I have not yet implemented capability to deal with LOGARITHMIC axes, but that's on my to-do list.

Comment only
27 Feb 2006 Dick Beresford

A very useful utility. Suggested additions and improvements are:
1) facility to deal with logarithmic as well as linear axes.
2) allow zoom function to work in calibration mode as well as in data grabbing mode so that axis limits can be defined more accurately.

13 Feb 2006 Leo Medo

Sorry, but wenn I start your code, I can see only GUI. If I browse a filename (Load Image) - only a path and image name will be shown, but I canĀ“t see anything... Please inform me what to do, thanks

Comment only
23 Dec 2005 Jiro Doke

Thanks for the comment. I think the problem might be that you don't have Image Processing Toolbox. But nice suggestions, I'll update it with IMAGE command to be more compatible. It should be up in the next update. In the meantime, you can download the newest version from here:

Comment only
22 Dec 2005 Tony Jones

The imshow command used at line 382 ('iH = imshow(A, map)') does not work in MATLAB R14 SP2. Replacing it with 'iH = image(A);
colormap(map);' solves the problem. Other than that a very useful but of code!

18 Aug 2005 Dewa Arsa

A very good code. I have tried it, it works well.

02 Aug 2005 Siva Venkat

good piece of code. useful for retrieving data points from images.

02 Jun 2005 radha proddaturi

perfect... would suggest to improve on finding data automatically when clicked on any particular line on the image

11 May 2005 Chen-Fen Huang  
21 Mar 2005

Added the functionality to start the GUI and open an image file from the command line.

Also embedded a sample image file to the function. Type 'GRABIT -sample'.

21 Mar 2005

Added the functionality to start the GUI and opening an image file from the command line.

Also embedded a sample image file into the fuction. Type 'grabit -sample'.

27 Dec 2005

Use IMAGE instead of IMSHOW for compatibility (does not require Image Processing Toolbox).

27 Dec 2005

Use IMAGE instead of IMSHOW for compatibility (does not require Image Processing Toolbox).

27 Dec 2005

Use IMAGE instead of IMSHOW for compatibility (does not require Image Processing Toolbox).

03 Mar 2006

Major code change. Added zoom feature during calibration. Added panning feature.

03 Mar 2006

Bug fix (typo)

13 Mar 2006

Animate view change and zooming for a better visual perception.

23 Mar 2006

Added mouse features: double-click to center view. right-click and drag to zoom. other minor code changes.

23 Mar 2006

Added mouse features: double-click to center view. right-click and drag to zoom. other minor code changes.

04 May 2006

Fixed loadImageFcn bug.

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