Then it is converted to device units, according to -Gdpi,
or a dpi value that is given by the output device,
or a default that is provided by each render.
-There are separate dpi values for x an y to allow for non-square pixels.
+There are separate dpi values for x and y to allow for non-square pixels.
Some renderers invert the Y axis and need an offset to place the
origin in the top left corner.
The default dpi for -Tpng is 96dpi (approximating the resolution