Hello,
Thank you for reaching out and I am happy to help!
The Minification is not used for the images. Minify is used for minifying and combining static assets like JS and CSS.
In the case of images, they need to be optimized. In the W3 Total Cache, there are some ways to optimize the images. WebP is a next-gen format that was designed specifically to compress graphics on the web. so you can use the Webp converter feature in the W3 Total Cache, to convert the images and serve them in the webp format.
Alternatively, you can also use the Lazyloading option for images.
If there is a need to resize images or scale them, you should either use some image optimization plugin for this or modify and re-upload images.
I hope this helps!
Thanks!