ImageMagick is an application with command-line utilities for manipulating size and resolution, correcting orientation, shearing and transforming images, correcting colors, and, even converting images over a wide range of formats.
The application accepts commands thought the CLI or by using scripts (such as Windows batch files).
For the examples I will use the picture below, called random.png.
Some example commands are:
magick -help
Show an overview of the command structure.
magick identify random.png
To get all of the pictures details.
magick random.png -resize 50% random.jpg
To change an image’s format and size.
magick *.png random.jpg
To convert all images in directory to another format.
ImageMagick is free software compatible with all major operating system such as Linux, Windows, Mac Os X, iOS, Android. It is distributed as a ready-to-run binary under an Apache 2.0 license.
The application is available to download here.