Broken addressing 'img' in nodes

Hello all

does anyone know how to fix my 'img' addressing ?

- When I access my site locally, the images links I put in nodes don't display because the link lacks the home directory of my site installation.
In order for it to work, i would have to put :
<img src="/InstallationDirectory/sites/default/files/images/myimage.jpg" alt="image" />
but then this would not work off the internet.

- When I access my sites from the internet, everything works fine. The link to the image is absolute and starts at "/sites"

I host my site on a local ubuntu server.

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I tried looking at the following modules but they don't seem to provide a solution for that dynamic change :
Pathologic
URL Replace Filter
Absolute src
Path Filter
Global Redirect
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anyone has any idea ?
Thanks