Dealing with WebP
WebP is a good image format for compressing images. There are two good application to convert to WebP.
WebP
Install
sudo aptitude install webp
Convert:
cwebp -q 80 image.png -o image.webp
Reconvert:
dwebp image.webp -o image.png
ImageMagick
ImageMagick is an powerful application for managing images (Not just for converting).
Install
sudo aptitude install imageMagick
Convert
convert image.png -quality 80 -define webp:lossless=true image.webp
References: