Convert images using the command line. You usually need to have imagemagick, graphicsmagick and cwebp
Webp is one of the best image types to store images in.
Convert images using graphicsmagick
gm convert jankaluza_thunderbird.jpg -resize 800x -quality 90 jankaluza_thunderbird.webpConvert all .png files to webpfiles in a folder. With the quality of 80
for file in *.png ; do cwebp -q 80 "$file" -o "$\{file%.png}.webp";