File Exchange

image thumbnail


version (23.4 KB) by jiro

jiro (view profile)

Extract (pick out) data points off image files.


Updated 01 Sep 2016

View License

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 MATLAB® R13. Tested up to R2006a

Comments and Ratings (184)

Amazing script!

Jatin Gera

Alexander May

Simply brilliant! Thank you!


Josh (view profile)


F H (view profile)

Thank you so much for that awesome tool. I've used it plenty of times over the years. Keep up the good work!

Tomas Hulan

A perfect tool! Thanks!

Chuchu Xiang

Kay Ackermann

Sameh Khan

Excellent code. FTI for those struggling with Drawmode, Erasemode deprecation.


'drawmode' . , 'fast', ...
'SortMethod' , 'depth', ...

and delete 'Erasemode', 'normal'

Your code should work fine in newer versions of MatLab, if those are the only issues.

Miguel Chavez

Jinpu Lin

Ricardo Brito

Ashwin Pathak

Which is the latest version of MATLAB for GRABIT command to work. Anyone?


For those who want to grab datapoints from a log-log graph, you can apply a simple transformation. For calibration, select points that are integer decades apart, then specify the decade (ex 3x10^1 -> 1, 3x10^4 -> 4) for the calibration values.

Once the data is grabbed, just apply the following transformation: [x, y] -> [constant1*10.^x, constant2*10.^y]. For example, where one axis limits are from 3x10^1 to 3x10^4, then the constant is 3. One such transformation can be executed as the following: a1 = [3*10.^Data001(:,1) 10.^Data001(:,2)];



Mattia (view profile)

Not supporte by R2017a :-(

Chuhan Deng

Great Functions!

Great utility! Thanks!

An extremely useful tool! Thanks!

zhumei sun

does it work for double Y axes?

Is it possible to use it when one axis is in log scale and not linear?

mod rany

Really great tool. I would suggest to build in an interpolation as a post processing option.

Vikram Babu

Great tool to extrapolate raw data from stress-strain curve images. Thanks for a great macro Jiro!

Wenyin Gong

kelvin zhang


Dennis Vogt

Slim Shady

How to make this understand that an axis is on log scale

Nick Savino

Effective tool. Useful with stress-strain curves

Nick Savino

tian chang


GLC (view profile)


Pedro (view profile)


Milad Jalali


rcbb (view profile)

Isaac Gentle


MMZ (view profile)

Great tool.. Thank you

Martin Erinin


Kang Gao

Nitisha Ahuja

How can I use it for log log plot?


Very useful function,

Lama Hamadeh

this code is pretty useful to get the x and y pixels of any jpeg image (or any other types of images). However, if I have a jpeg thermal image and I need to extract the temperature data from it, i.e., the value beneath each point (xpixel,ypixel), this code is not useful.
P.S: ginput function in MATLAB does, to some extent, the same job as this code.

Haibin Pan

It's great.Thanks the author.

Paolo Di Re

When I grab a point, the function draws a red dot on the image.
Is there a way to change the color of the dot from red to another color, for instance cyan, even by modifing the function? Thanks

Great tool.
How to extract the data points if the one of the axis is in logscale? For e.g. yaxis in log scale.

xingya chen


Kurt Duclos

Great GUI. If you could set it for a semilogy, semilogx, or loglog instead of linear only, that would be incredible. Also, the cursor accuracy when grabbing data points be improved by making it more like the cursor when selecting the X, Y axes.

Dale Smith

shiwen wang

Thank U so much!



MG (view profile)

I like the interface and resolution allowed by the algorithm. However, when I tried using on a plot, it consistently is not correctly scaling my "grabbed" points to neither the min-max x or y coordinates that I input.

Beichuan Hong

Thx for this file!

excellent tool!
thank you so much!


MM (view profile)




Nabin Paudel

Error message, unable to expand "" into downloads. Any solutions for this issue yet ?


Rosemary Le

There is an error message when attempting to unzip the file:

"Unable to expand "" into "Downloads".
(Error 1 - Operation not permitted.)"

Just wanted to notify --


It seems quite useful, but on OSX 10.11.6, Version R2016a, it warns me of 2 deprecated properties which "may go away in future releases." (DrawMode and EraseMode) So it looks like it needs an update. If I can I may try to update this as it might be a good chance for learning some new things for me.
I found that it's a little tricky to set up the axes as the cursor is quite fine, but that is an advantage really. One needs to be careful and practice a bit. Also Log plots need you to choose the exponent so again a tad tricky but practice should help. Not obvious how else you could do it. And "max" really does mena the maximum value on the scale.

Srikanth Divi

rahul verma

How we can save the image, after garbing points.
is there any way to get the selected image.

great tool!

Thank you for this!


GE (view profile)

this is a very use full application,
Thank you

Tai Yunxin

Qiyan Lian

It is really a amazing GUI,but there is a warning, EraserMode will not be it should be updated.

Qiyan Lian


Aditya (view profile)

Really easy and straightforward to use. No unnecessary complications or extra features. Works great!


Zac Milne

I use this all of the time for analyzing data from others' work. I wish there was a function to deal with log axes.

Paul Martin

Just what the doctor ordered, worked well first time. Thank you Jiro!


Deepan J

It worked well and helped me a lot. Thanks!

Jake G

Jake G (view profile)

Great software, it was a little dated so I needed to tweak it a bit to deal with log scale axis and get rid of those annoying warnings.


Erik (view profile)


Very useful software! Very intuitive and easy to use. Exactly what I needed.

very good software, so much thanks!


Emon (view profile)

Excellent. Thanks a lot.

Joris Meurs

Great work! Very useful


Very useful code. This is what I was looking for. Thanks


Ivan (view profile)

Andrew Stamps

This has been a great utility for me over the years. However, it appears to be showing its age with the new graphics system. I am now seeing the following warnings when starting the tool:

Warning: The DrawMode property will be removed in a future release. Use the SortMethod property instead.
> In grabit (line 471)
Warning: The EraseMode property is no longer supported and will error in a future release. Use the ANIMATEDLINE function for animating lines
and points instead of EraseMode 'none'. Removing instances of EraseMode set to 'normal', 'xor', and 'background' has minimal impact.


Exactly what I needed. The only thing that was not intuitive to me was hitting [ENTER] to indicate that I was done specifying each axis.



Use (view profile)

aaron pung

Straight-forward, simple, and gave me everything I was looking for, and much more.
- Upload image file
- Choose/define X,Y axes
- Zoom/Pan to area of interest
- Click to record desired datapoints
- Plot is generated in real-time
- Data table can be saved for further processing!

Worked well for simple data point extraction from a PNG.

For those of you getting the error "unexpected matlab operator", make sure you call "addpath" and add the directory in which this .m file is stored. The main function calls other functions within the .m file.


amazing program!!!! thank you very much!!!!


KSSV (view profile)


Thank you so much . It was so usefull


Rahul (view profile)

Super! This just saved me quite a bit of work. Thank you.


Xin (view profile)

Yuan Feng

excellent work a nice tool


Edgar (view profile)

I wonder if there is a way to automatically recognize the waves if the image has a wave of a unique color and if there is a way to do multiple files instead of clicking points one by one. Thanks!

Does make my life easier, thank you

Faezeh F

That's great. Thank you very much!


daniel (view profile)

WOW!! Absolutely beautiful, I love it, thanks!!!!


Punit (view profile)

For people asking about logarithmic axis...
You can put the values for calibration of log axis as 1, 2, 3 instead of 10, 100, 1000, and then when you plot the data just take 10^(axisValues).


Best, Thanks



Bikash (view profile)

It is working fine. Nice work.


Ole (view profile)

How does it work with log axis ?
Thank you.


Nikhil (view profile)


Nitin (view profile)

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


Amit (view profile)

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.


Won't work in 2013b though

Yuji Zhang

Works so well! Thank you for your contribution Jiro~

Suggestion: automatic recognize curve (if possible)


arnold (view profile)

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 ;)

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!


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

Zhen Chen


Luke (view profile)

Ahmed Ali

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

James Herman


mike (view profile)

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.


Oscar (view profile)

It is very helpful, veru well done


very nice tool!


Thomas (view profile)

Nassim Khaled


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.




Enrico (view profile)

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

Ram Lakshmi


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

Torsten Vogel

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.


Brian (view profile)

A very useful application.

a c


ghgf ghf

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.

Mikkel Pedersen

Super tool!

Need the capability to use log-axes though.

Lorenzo Luini

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

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

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.

Amandine Cagnioncle

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

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)

Avi Pal

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


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).

Jean-Luc Dellis

Thanks a lot. Good Job.

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?

Pankaj Porwal

Just loved it. Very good interface also.

Hector Mancha

Very usefull,

Cong Le

Lars Sundstrom

Extremely useful. Thank you very much for sharing.

Nick Peters

Excellent tool. Thanks for posting.

Seis Errs

very useful tool. Thanks a lot.

John Terry

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

iman satria

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.

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.

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 can´t see anything... Please inform me what to do, thanks

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!

Dewa Arsa

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

Siva Venkat

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

radha proddaturi

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

Chen-Fen Huang


Updated license

Fixed bug. Now, grayscale images can be loaded.

Fixed loadImageFcn bug.

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

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

Animate view change and zooming for a better visual perception.

Bug fix (typo)

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

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

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

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

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'.

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'.

MATLAB Release Compatibility
Created with R13
Compatible with any release
Platform Compatibility
Windows macOS Linux


Discover Live Editor

Create scripts with code, output, and formatted text in a single executable document.

Learn About Live Editor