playblast to djviewer, http://djv.sourceforge.net/index.html

djiviewer.py

import maya.utils as utils
import maya.cmds as cmds
import subprocess
import threading
import tempfile
import platform
import os.path
import shutil
import re
import os

def get_windows_command():
    root = r"C:\Program Files"
    for folder in os.listdir(root):
        if re.match(r"djv-[\d\.]+-Windows.", folder):
            return os.path.join(root, folder, "bin", "djv_view.com")

def render(path):
    sequence = os.path.join(path, "sequence")
    cmds.playblast(
        viewer=False,
        showOrnaments=False,
        format="image",
        filename=sequence.replace("\\", "/")
        )

def preview(folder, command):
    try:
        for f in os.listdir(folder):
            start = os.path.join(folder, f)
            subprocess.call((command, start)) # Block
            break
    finally:
        shutil.rmtree(folder)

system = platform.system()
if system == "Windows":
    command = get_windows_command()
else:
    raise Exception("OS not supported")
if command and os.path.isfile(command):
    tmp_folder = tempfile.mkdtemp()
    try:
        render(tmp_folder)
    finally:
        th = threading.Thread(target=preview, args=(tmp_folder, command)).start()
else:
    import webbrowser
    print "Cannot find DJVIewer. Please download and install it."
    webbrowser.open("http://djv.sourceforge.net/index.html")