generate color reduced smaller size 8bit PNG using pngquant

scripts/render.py

@@ -478,6 +478,9 @@ class JobRenderer(threading.Thread):
                 img.save(prefix + '.jpg', quality=50)
                 img.thumbnail((200, 200), Image.ANTIALIAS)
                 img.save(prefix + THUMBNAIL_SUFFIX)
+                pngquant_cmd = [ "pngquant", "--output", "%s.8bit.png" % prefix,
+                                 "%s.png" % prefix ]
+                subprocess.check_call(pngquant_cmd)
 
     def run(self):
         """Renders the given job, encapsulating all processing errors and

www/maposmatic/models.py

@@ -205,6 +205,7 @@ class MapRenderingJob(models.Model):
         allfiles = {'maps': {}, 'indeces': {}, 'thumbnail': [], 'errorlog': []}
 
         formats = www.settings.RENDERING_RESULT_FORMATS
+        formats.append('8bit.png')
         formats.append('jpg')
         for format in formats:
             map_path = self.get_map_filepath(format)