Calc: How do I reduce ods file size by resizing embedded images

[clear]

I’d like to reduce the size of my spreadsheet file. The ods file contains a number of very large jpgs embedded in cells. How do I resize the embedded image (not how it is displayed, but the size of the actually embedded object/jpg).

The only approach that comes to mind is to somehow export all the images (I don’t know how to do that), then somehow convert the embedding into a link to the corresponding export jpg (I don’t know how to do that either), resize the exported images (I know how to do that), then convert all the links into to embedded images (I don’t know how to do that either).

[Lupp]

Having inserted a .jpg its context menu should show an item Compress.
Reducing the resolution and/or the quality should result in less needed bytes (within limits)…

[bantoniof]

@clear

to somehow export all the images

• Always work with a copy of the original document.

0. LibreOffice documents are Zip compressed files.

1. Open the ODS file with a compressor/decompressor
   Inside the zip you will find a folder with the name Images.
   In that folder are the images embedded in the document with a numerical name.

2. Save the images (unzipped) in a folder on your computer.

3. Use an image optimization program to reduce their size on disk but do not change the name or extension of the images.

4. Replace the optimized images in the compressed ODS FIle