The writer’s ODT format also captures the images contained in a document. How to save them separately.
Libreoffice Writer: Save document images
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If you want to save the images contained in a Libreoffice document separately, click on an image with the right mouse button and select “Save”. However, this is quite a time-consuming job for a document with many images.
It’s faster if you rename the text file and give it the ending “ZIP”. You can ignore the Windows warning that this may render the file unusable. In the following, right-click the file in Explorer and select “Extract all”. The pictures are then in the “Pictures” subfolder, but they have been given new, cryptic names. If you use the 7-Zip file manager to open them instead, you can unzip the images with their original names via “File -> Open internally”.
LibreOffice Writer: Five How to Get Started