<2015.6.26>

On the Linux/Cygwin/OS X command line:

$ convert -thumbnail 300 Cate_Brown_Roldan_SfN_2014_FINAL.pdf outputFileName.png

To create thumbnail image of one page of a multi-page PDF file (like a journal article):

$ convert -thumbnail pdfFileName.pdf[0] outputFileName.png

[0] is for first page, [1] for second, etc.

<2016-01-08>

convert rwls_residual_time_series.png -gravity South -crop 0x30%+0+0 rwls_residual_time_series_crop.png

This means: “Crop from bottom up (-gravity South) leaving all width and removing 30% of height (0x30%+0+0)”

From this and related pages:

http://www.imagemagick.org/Usage/crop/#crop_gravity