Simple command line script to convert a file from any image format to another. Based on Python Imaging Library. Not based on ImageMagick.

img2img.py

#!/usr/bin/env python2.7

'''
Author: Yotam Gingold <yotam (strudel) yotamgingold.com>
Any copyright is dedicated to the Public Domain.
http://creativecommons.org/publicdomain/zero/1.0/
'''

import os, sys

def usage():
    print >> sys.stderr, 'Usage: %s [--clobber] input output (image type is inferred from the extension)' % (sys.argv[0],)
    sys.exit(-1)

argv = list( sys.argv )
del argv[0]

## Optional arguments
kClobber = False
try:
    index = argv.index( '--clobber' )
    del argv[ index ]
    kClobber = True
except ValueError: pass

if len( argv ) != 2:
    usage()

inpath = argv[0]
del argv[0]

outpath = argv[0]
del argv[0]

if os.path.exists( outpath ) and not kClobber:
    print >> sys.stderr, 'Clobber not specified (--clobber) and outpath exists:', outpath
    usage()

import Image
img = Image.open( inpath )
## Quality parameter only affects JPEG's; PIL's default is too low.
img.save( outpath, quality = 90 )