ImageMagick

ImageMagick is a command-line tool for processing image files.

This tool is not suitable for processing RAW images; darktable is recommended instead.

environment	command
archlinux	`pacman -S imagemagick`
mingw-w64	`pacman -S mingw-w64-i686-imagemagick`
brew on mac	`brew install imagemagick`

Please note that you must also install libraries to handle specific image formats.

format	required library
webp	libwebp

convert src.png [options] dst.jpg  # output format is recognized by an extension

option	target format	description
-auto-orient	*	Rotates the raw image according to the metadata orientation, and removes the orientation tag.
-resize X%	*	Resize the image by the specified percentage.
-strip	*	Removes any metadata.
-define webp:method=N	webp	Quality of webp format(1~6). A higher value results in stronger compression and lower quality.

convert $i -define webp:method=6 -resize 15% -auto-orient -strip ${i%.jpg}.webp

Install