Extract data from .PNG file

Hi all,

I have an x,y,z plot saved as a .PNG file. I want to extract the data from the x, y and z axes. Preferably in matrix form. Any tips?

Answer 1

[Sebastian Castro]

I'd recommend using the Data Theif (yes, they misspelled it too) entry in the File Exchange. It lets you click on an image to calibrate its dimensions and extract X-Y data points.

... Now, I'm not sure if that works for 3-D since an image is 2-D, but that would be true of almost any image processing algorithm as well (unless you have multiple images or depth data).

Was that JPG image saved from MATLAB? If possible, it would make things a lot easier if whoever generated that figure saved it as a .fig file instead. Then, you could load it into MATLAB and get the exact point locations.

- Sebastian

[Karam Chehade]

hi, thanks for the recommendation. My original file is .png and I tried converting it to a .fig online. After uploading it to the Data Theif, I got the following message. What can I do to fix this?

Thank you!

[Image Analyst]

According to the error message, it expects a .mat file, not a .fig file. Try saving your image array into a .mat file instead.

[Walter Roberson]

.fig files are mat files, and it did in fact try to read it as a binary mat file.

The problem must be with the way the .fig was created.

Answer 2

[Image Analyst]

Another option is http://www.mathworks.com/matlabcentral/fileexchange/36904-matlab-script-for-digitizing-a-published-graph. I haven't tried it so I can't help you with it.

[AbdulAzeez Ajenipa]

It does not work

[george panayotov]

Yes, does not allow to export data. Don't waste time with it, just a click bait.

[Walter Roberson]

Run it as a function; the digitized data will be returned.