Imagemagick

Stuff

-resize 100x40
-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

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