Creating PNG output of music snippets is always the size of a page

[Charles Cave]

When I run lilypond with the --png command line switch, the generated
PNG file is the size of the printed page.  How can I make this image small 
enough
so the image is cropped?  It is rather tedious to open the file with GIMP and
manually crop the image.

The image created from the input file below was 859 x 1111 pixels
(8.506 x 11.001 inches ... obviously the page size).

I am running LilyPond 2.8.3 on Windows XP

E:\>lilypond --png  noscore.ly
GNU LilyPond 2.8.3
Processing `noscore.ly'
Parsing...
Interpreting music... [1]
Preprocessing graphical objects...
Calculating line breaks... [2]
Calculating page breaks...
Layout output to `noscore.ps'...
Converting to PNG...


noscore.ly contains:

\version "2.8.3"

\score {
\context Staff \relative c'' { c8 c c16 c c c }
    \layout{
    \context {
      \Staff
      \remove Staff_symbol_engraver
    }
}
}