Here is the process:
- find the canonical name of the label in the labels' taxonomy (it's the first item in the list of the labels' synonyms, eg. en:100% vegetable)
- get the logo in a good quality: avoid using the contributor's photo which are not suited for this case; most labels have official websistes high quality logos, sometimes in vector format (even better for us); as long as we use a logo to objectively inform about the presence of a label on the packaging of a product, there is no need to ask permission.
name the file like this: name-of-the-label.[width]x90.png where width is the width for the logo when it is 90 pixels high. The filenames need to be unaccented, in lowercase and using "-" instead of spaces.
- then add the logo in the directory that corresponds to its canonical name. If the canonical name is en:something, then they need to be in /en/. The root directory for logos is https://github.com/openfoodfacts/openfoodfacts-server/tree/main/html/images/lang