Saving nltk drawn parse tree to image file

Is there any way to save the draw image from tree.draw() to an image file programmatically? I tried looking through the documentation, but I couldn't find anything.

Using the nltk.draw.tree.TreeView object to create the canvas frame automatically:

>>> from nltk.tree import Tree
>>> from nltk.draw.tree import TreeView
>>> t = Tree.fromstring('(S (NP this tree) (VP (V is) (AdjP pretty)))')
>>> TreeView(t)._cframe.print_to_file('output.ps')

Then:

>>> import os
>>> os.system('convert output.ps output.png')

[output.png]:

I had exactly the same need, and looking into the source code of nltk.draw.tree I found a solution:

from nltk import Tree
from nltk.draw.util import CanvasFrame
from nltk.draw import TreeWidget

cf = CanvasFrame()
t = Tree.fromstring('(S (NP this tree) (VP (V is) (AdjP pretty)))')
tc = TreeWidget(cf.canvas(),t)
cf.add_widget(tc,10,10) # (10,10) offsets
cf.print_to_file('tree.ps')
cf.destroy()

The output file is a postscript, and you can convert it to an image file using ImageMagick on terminal:

$ convert tree.ps tree.png

I think this is a quick and dirty solution; it could be inefficient in that it displays the canvas and destroys it later (perhaps there is an option to disable display, which I couldn't find). Please let me know if there is any better way.

To add to Minjoon's answer, you can change the fonts and colours of the tree to look more like the NLTK .draw() version as follows:

tc['node_font'] = 'arial 14 bold'
tc['leaf_font'] = 'arial 14'
tc['node_color'] = '#005990'
tc['leaf_color'] = '#3F8F57'
tc['line_color'] = '#175252'

Before (left) and after (right):