Common options

Option	Description
-resize 100x40	Resize to a dimension
-crop 40x30+10+10	(width)x(height)+(x)+y
-crop 40x30-10-10	(width)x(height)+(x)+y
-flip	Vertical
-flop	Horizontal
-transpose	Flip vertical + rotate 90deg
-transverse	Flip horizontal + rotate 270deg
-trim	Trim image edges
-rotate 90	Rotate 90 degrees

Resize to fit

convert input.jpg -resize 80x80^ -gravity center -extent 80x80 icon.png

Convert all images to another format

mogrify -format jpg -quality 85 *.png

Make a pdf

convert *.jpg hello.pdf

References

• http://www.noah.org/wiki/ImageMagick
• https://www.imagemagick.org/