Using ImageMagick on Linux and macOS

ImageMagick is a free software package available on all major operation systems. It can read and transform more than 100 different iamge formats.

Installing ImageMagick:

Example for converting an images from one format to another:

convert input_image.png output_image.jpg

Examples for resizing/transforming images:

Removing transparency in an image:

convert -flatten input_image.png output_image.png