[ImageMagick] resize pdf files

To resize the pdf files in mac (or linux) platform, the ImageMaick package provides convenient way.

Once you install the image magick package, you can resize the pdf files like below:

 

> convert -density 200 file_origin.pdf file_outcome.pdf

Here, you can change the density number to control the size of output. 

 

The information of pdf files can be found by

 

> identify -verbose file.pdf | head