MATLAB Answers

Text inside image file

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Valeriy on 19 Dec 2019
Commented: Valeriy on 26 Dec 2019
Many formats of image files like jpg, png, tiff enable to read/write inside binary file information some comments, captions (so called IPTC data), EXIF data. They can accesible, for example, by XnView viewer, by Edit\Metadata\Edit IPTC data\ or by <Ctrl i> key combination.
It would be very useful and convenient to read/write such fields from Matlab to keep there some service information deals with image processing or parameters of image acquisiton.
Searching of Matlab answers and file exchange shows only possibility to read EXIF data or putting comments, annotation directly into image of such image file.
Is it possible and how is it possible to operate with such fields from Matlab?
Thank you


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Accepted Answer

Walter Roberson
Walter Roberson on 19 Dec 2019
MATLAB only permits reading EXIF, and only for some image formats.
There is a File Exchange contribution for MS Windows that can invoke an external .exe to write EXIF information.
EXIF-like information can be written into TIFF files if you use the Tiff() class interface and set the appropriate tag fields. It is not all that convenient to do so, but it can be done.
Those are the only things that are available.


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Valeriy on 24 Dec 2019
Thank you, Walter, for your detailed answer. Now situation is much more clear. It seems that for purposes I have mentioned, it is reasonable to use FileName, to code/decode service information into it.
From the other hand, image files have a lot of possibilities to keep text information. Probably further Matlab development will open for user possibility to use it, to work with IPTC fields.
Walter Roberson
Walter Roberson on 24 Dec 2019
EXIF effectively doesn't work for any of the common image formats except for JPEG and TIFF, and the EXIF wikipedia page explains why it is less than ideal in practice (data pointers are only relative, so you have to rebuild the pointers every time you modify the size of anything; encrypted private tags are used by some manufacturers to lock you into their eco-system; cameras / instruments do not have full EXIF processing and so moving an adjusted image back to the device is often incompatible.)
Valeriy on 26 Dec 2019
Dears Walter Robertson, Image Analyst,
At first, Merry Christmas!
Thanks for your help. As usually, reading Matlab Help is useful activity: after all I have found there answer on my question.
To write additional information into image file one can use:
imwrite(MatrVar,'FileName.jpg','Comment','This is my information'); % or
imwrite(MatrVar,'FileName.png','Comment','This is my information',...
'Author','Another information','Description','Additional information field'); % or
imwrite(MatrVar,'FileName.tif','Description','This is my information')
To read this information:
info = imfinfo('FileName.png'); % for example
MyFirstInformation = info.Comment;
AnotherInformation = info.Author; % etc.
Verification shows that it works.

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More Answers (1)

Image Analyst
Image Analyst on 19 Dec 2019


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