THESE CODES ARE PROVIDED FOR AN EXAMPLE OF HOW TO USE IMAGEMAGICK WITH PHP. CARE SHOULD BE TAKEN WHEN ACCEPTING USER INPUT.
I TAKE NO RESPONSABILTY FOR ANY PROBLEMS THAT MAY OCCURE WHEN USING ANY OF THIS CODE.
IT IS UP TO YOU TO SECURE THE CODE AND VALIDATE USER INPUT.
The sizes used in ImageMagick are in pixels; to get an image into a size for printing e.g. 6"x4" you need to do something like this:
exec("convert input.jpg -resize 600x400 -density 100x100 output.jpg");