Steps

• Move all your image files to a folder
• calculate it’s folder size using du
• create a copy of the folder.
• install imagemagick

brew install imagemagick

• in this folder, perform the following actions:

mkdir compressed
for i in *; do convert $i -resize 40% compressed/$i; done;

The above will compress all images by making the size 40% of the initial size and will move it to a folder called compressed

• Check folder structure again using du
• if it’s still too much, repeat again but this time reduce quality to even lower