imagemagick: command line tools

animates an image sequence on any X server

mathematically and visually annotate the difference between an image and its reconstruction

overlaps one image over another

interprets and executes scripts written in the Magick Scripting Language (MSL)

convert between image formats as well as resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more

convert -density 150 SN-085.pdf SN-085.tif

density defines the resolution of the output image (default is 72)

displays an image or image sequence on any X server

describes the format and characteristics of one or more image files

saves any visible window on an X server and outputs it as an image file. You can capture a single window, the entire screen, or any rectangular portion of the screen.

resize an image, blur, crop, despeckle, dither, draw on, flip, join, re-sample, and much more. Mogrify overwrites the original image file, whereas, convert writes to a different image file.

create a composite image by combining several separate images. The images are tiled on the composite image optionally adorned with a border, frame, image name, and more.

http://www.imagemagick.org