Backend is node-imagemagick.
tempPath- image to generate a thumbnail for
makeTemp- a function which generates a tempfile and accepts a suffix
tempPath- path to the generated thumbnail
format- what format to save in, such as 'jpg'. defaults to 'png'.
quality- between 0 and 1. only applies for some formats.
width- width of thumbnail
height- height of thumbnail
gravity- one of ['NorthWest', 'North', 'NorthEeast', 'West', 'Center', 'East', 'SouthWest', 'South', 'SouthEast']