As regards club space resources:

Therefore, one terabyte reduced by 92% would be  81.92 gigabytes.

and 

 1 GB reduced by 92% would leave us with 0.08 GB, which is  80 MB

So I will be doing this as in my case it is a case of needs must or no more images for me.

The pros and cons are all about "lossyness" and webp is highly controllable in this.

 

This is a cli (command line interface) tool so not easy for the uninitiated. That's why I mention our site scripting it in. But I am very impressed at this point.

Apologies, this should now be a blog post. I will see if I can move it there - which is now this text 

So a Mac terminal command to convert all jpegs and jpgs if not already converted, to webp files, with the following two warnings

1 - the cwebp command is given its complete absolute path to itself so I do not have to mess with editing path names and

2- the target directory/folder complete absolute path is also given. So if you have your path correct to your cwebp installation directory all you need do is edit the path to your folder containing your jpg and jpeg images. 

In English: In my specified folder find jpegs and jpgs that have not yet been converted and convert them to webp format.

find "/Volumes/Data/Dropbox/! Cars/BDR Collection" -type f \( -name "*.jpeg" -o -name "*.jpg" \) -print0 | xargs -0 -I {} sh -c '[ ! -f "${1%.*}.webp" ] && /Applications/libwebp-1.3.2-mac-arm64/bin/cwebp "$1" -o "${1%.*}.webp"' _ {}

If we have terminal access to our site then to clarify, here's the breakdown:

• find "/Volumes/Data/Dropbox/! Cars/BDR Collection" starts the search in the specified directory.
• -type f restricts the search to files only.
• \( -name "*.jpeg" -o -name "*.jpg" \) is the expression that matches files ending in .jpeg or .jpg.
• -print0 outputs the full file path followed by a null character, ensuring that filenames with special characters (like spaces) are handled correctly.
• The pipe | sends the output of find to xargs.
• xargs -0 reads null-terminated strings, which is necessary because of the -print0 option used in find.
• sh -c '...' is the command executed for each file, where the existence of a .webp file with the same base name is checked before conversion.

This will include all nested subdirectories under the starting folder. If you ever need to limit the depth of the recursive search, find has a -maxdepth option that you can use to specify how deep in the directory tree to search.

HOWEVER, this changes the file extensions and a further site wide edit would have to fix that. Methinks hero required for that.