I prefer the PHP version of ImageMagick as PHP is a better scripting tool than 'cli'. The manual is a bit hard to follow as things are essentially undocumented. However, if you want to carefully prepare a batch of images, going to PHP is taking it to the next level.

Particularly interesting are features such as being able to save images in different colour spaces, e.g. 4:2:0, going lo-res on the chroma for a lower ultimate file size in jpg.

If I had a lifetime spare I would complete the PHP Imagick documentation and write a version of Fred's scripts in PHP, so they can be chained together in a nifty object oriented way...