diff --git a/main.py b/main.py
index f4c96da..f6cf3a1 100644
--- a/main.py
+++ b/main.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 '''
 Copyright 2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 
@@ -27,10 +26,25 @@
 DRYRUN = None
 IMAGES_TO_KEEP = None
 IGNORE_TAGS_REGEX = None
-FILTER_TAGS_REGEX = None
-REPOSITORIES_FILTER = None
+
+
+def initialize():
+    global REGION
+    global DRYRUN
+    global IMAGES_TO_KEEP
+    global IGNORE_TAGS_REGEX
+
+    REGION = os.environ.get('REGION', "None")
+    DRYRUN = os.environ.get('DRYRUN', "false").lower()
+    if DRYRUN == "false":
+        DRYRUN = False
+    else:
+        DRYRUN = True
+    IMAGES_TO_KEEP = int(os.environ.get('IMAGES_TO_KEEP', 100))
+    IGNORE_TAGS_REGEX = os.environ.get('IGNORE_TAGS_REGEX', "^$")
 
 def handler(event, context):
+    initialize()
     if REGION == "None":
         partitions = requests.get("https://raw.githubusercontent.com/boto/botocore/develop/botocore/data/endpoints.json").json()[
                 'partitions']
@@ -41,20 +55,6 @@ def handler(event, context):
     else:
         discover_delete_images(REGION)
 
-def ignore_tags_image(image,running_sha):
-    skip = False
-    if (FILTER_TAGS_REGEX != ""):
-        skip = True
-
-    for tag in image['imageTags']:
-        if ( "latest" in tag
-                or re.compile(IGNORE_TAGS_REGEX).search(tag) is not None
-                or (running_sha and image['imageDigest'] in running_sha)):
-            return True
-        if (re.compile(FILTER_TAGS_REGEX).search(tag) is not None):
-            skip=False
-    return skip
-
 
 def discover_delete_images(regionname):
     print("Discovering images in " + regionname)
@@ -64,11 +64,9 @@ def discover_delete_images(regionname):
     describe_repo_paginator = ecr_client.get_paginator('describe_repositories')
     for response_listrepopaginator in describe_repo_paginator.paginate():
         for repo in response_listrepopaginator['repositories']:
-            if REPOSITORIES_FILTER:
-              if repo['repositoryName'] in REPOSITORIES_FILTER:
-                repositories.append(repo)
-            else:
-              repositories.append(repo)
+            repositories.append(repo)
+
+    # print(repositories)
 
     ecs_client = boto3.client('ecs', region_name=regionname)
 
@@ -132,17 +130,14 @@ def discover_delete_images(regionname):
 
         print("Number of running images found {}".format(len(running_sha)))
 
-        image_count = 0
         for image in tagged_images:
-            if ignore_tags_image(image,running_sha):
-                continue
-            if image_count >= int(IMAGES_TO_KEEP):
+            if tagged_images.index(image) >= IMAGES_TO_KEEP:
                 for tag in image['imageTags']:
-                    append_to_list(deletesha, image['imageDigest'])
-                    append_to_tag_list(deletetag, {"imageUrl": repository['repositoryUri'] + ":" + tag,
-                                                    "pushedAt": image["imagePushedAt"]})
-            image_count += 1
-
+                    if "latest" not in tag and re.compile(IGNORE_TAGS_REGEX).search(tag) is None:
+                        if not running_sha or image['imageDigest'] not in running_sha:
+                            append_to_list(deletesha, image['imageDigest'])
+                            append_to_tag_list(deletetag, {"imageUrl": repository['repositoryUri'] + ":" + tag,
+                                                        "pushedAt": image["imagePushedAt"]})
         if deletesha:
             print("Number of images to be deleted: {}".format(len(deletesha)))
             delete_images(
@@ -202,27 +197,19 @@ def delete_images(ecr_client, deletesha, deletetag, id, name):
 if __name__ == '__main__':
     request = {"None": "None"}
     parser = argparse.ArgumentParser(description='Deletes stale ECR images')
-    parser.add_argument('-dryrun', help='Prints the repository to be deleted without deleting them', default=os.environ.get('DRYRUN', "true"),
+    parser.add_argument('-dryrun', help='Prints the repository to be deleted without deleting them', default='true',
                         action='store', dest='dryrun')
-    parser.add_argument('-imagestokeep', help='Number of image tags to keep', default=os.environ.get('IMAGES_TO_KEEP', "100"), action='store',
+    parser.add_argument('-imagestokeep', help='Number of image tags to keep', default='100', action='store',
                         dest='imagestokeep')
-    parser.add_argument('-region', help='ECR/ECS region', default=os.environ.get('REGION', "None"), action='store', dest='region')
-    parser.add_argument('-repositories', help='Filter for repositories names discovery separated by space', default=os.environ.get('REPOSITORIES_FILTER', "").split(),
-                         nargs='+', action='store', dest='repositories_filter')
-    parser.add_argument('-ignoretagsregex', help='Regex of tag names to ignore', default=os.environ.get('IGNORE_TAGS_REGEX', "^$"), action='store', dest='ignoretagsregex')
-    parser.add_argument('-filtertagsregex', help='Regex filter of tag names to limit on images with matching tag', default=os.environ.get('FILTER_TAGS_REGEX', ""), action='store', dest='filtertagsregex')
+    parser.add_argument('-region', help='ECR/ECS region', default=None, action='store', dest='region')
+    parser.add_argument('-ignoretagsregex', help='Regex of tag names to ignore', default="^$", action='store', dest='ignoretagsregex')
 
     args = parser.parse_args()
-
-    REGION = args.region
-    if args.dryrun.lower() == "false":
-        DRYRUN = False
+    if args.region:
+        os.environ["REGION"] = args.region
     else:
-        DRYRUN = True
-
-    IMAGES_TO_KEEP = args.imagestokeep
-    IGNORE_TAGS_REGEX = args.ignoretagsregex
-    FILTER_TAGS_REGEX = args.filtertagsregex
-    REPOSITORIES_FILTER = args.repositories_filter
-
+        os.environ["REGION"] = "None"
+    os.environ["DRYRUN"] = args.dryrun.lower()
+    os.environ["IMAGES_TO_KEEP"] = args.imagestokeep
+    os.environ["IGNORE_TAGS_REGEX"] = args.ignoretagsregex
     handler(request, None)