diff --git a/pixel_link.py b/pixel_link.py
index 367196e..1f287f8 100644
--- a/pixel_link.py
+++ b/pixel_link.py
@@ -280,7 +280,6 @@ def decode_image(pixel_scores, link_scores,
         raise ValueError('Unknow decode method:%s'%(config.decode_method))
 
 
-import pyximport; pyximport.install()    
 from pixel_link_decode import decode_image_by_join
 
 def min_area_rect(cnt):
diff --git a/pixel_link_decode.py b/pixel_link_decode.py
new file mode 100644
index 0000000..19d74af
--- /dev/null
+++ b/pixel_link_decode.py
@@ -0,0 +1,33 @@
+import numpy as np
+
+def get_neighbours(x, y):
+    return [(x - 1, y - 1), (x, y - 1), (x + 1, y - 1), \
+        (x - 1, y),                 (x + 1, y),  \
+        (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)]
+
+def is_valid_cord(x, y, w, h):
+    return x >=0 and x < w and y >= 0 and y < h
+    
+def decode_image_by_join(pixel_scores, link_scores, pixel_conf_threshold, link_conf_threshold):
+    pixel_mask = pixel_scores >= pixel_conf_threshold
+    link_mask = link_scores >= link_conf_threshold
+    done_mask = np.zeros(pixel_mask.shape, np.bool)
+    result_mask = np.zeros(pixel_mask.shape, np.int32)
+    points = list(zip(*np.where(pixel_mask)))
+    h, w = np.shape(pixel_mask)
+    group_id = 0
+    for point in points:
+        if done_mask[point]:
+            continue
+        group_id += 1
+        group_q = [point]
+        result_mask[point] = group_id
+        while len(group_q):
+            y, x = group_q[-1]
+            group_q.pop()
+            if not done_mask[y,x]:
+                done_mask[y,x], result_mask[y,x] = True, group_id
+                for n_idx, (nx, ny) in enumerate(get_neighbours(x, y)):
+                    if is_valid_cord(nx, ny, w, h) and pixel_mask[ny, nx] and (link_mask[y, x, n_idx] or link_mask[ny, nx, 7 - n_idx]):
+                        group_q.append((ny, nx))
+    return result_mask
diff --git a/pixel_link_decode.pyx b/pixel_link_decode.pyx
deleted file mode 100644
index c45d6b5..0000000
--- a/pixel_link_decode.pyx
+++ /dev/null
@@ -1,114 +0,0 @@
-import cv2
-import numpy as np
-
-import util
-PIXEL_NEIGHBOUR_TYPE_4 = 'PIXEL_NEIGHBOUR_TYPE_4'
-PIXEL_NEIGHBOUR_TYPE_8 = 'PIXEL_NEIGHBOUR_TYPE_8'
-
-
-def get_neighbours_8(x, y):
-    """
-    Get 8 neighbours of point(x, y)
-    """
-    return [(x - 1, y - 1), (x, y - 1), (x + 1, y - 1), \
-        (x - 1, y),                 (x + 1, y),  \
-        (x - 1, y + 1), (x, y + 1), (x + 1, y + 1)]
-
-
-def get_neighbours_4(x, y):
-    return [(x - 1, y), (x + 1, y), (x, y + 1), (x, y - 1)]
-
-
-def get_neighbours(x, y):
-    import config
-    neighbour_type = config.pixel_neighbour_type
-    if neighbour_type == PIXEL_NEIGHBOUR_TYPE_4:
-        return get_neighbours_4(x, y)
-    else:
-        return get_neighbours_8(x, y)
-    
-def get_neighbours_fn():
-    import config
-    neighbour_type = config.pixel_neighbour_type
-    if neighbour_type == PIXEL_NEIGHBOUR_TYPE_4:
-        return get_neighbours_4, 4
-    else:
-        return get_neighbours_8, 8
-
-
-
-def is_valid_cord(x, y, w, h):
-    """
-    Tell whether the 2D coordinate (x, y) is valid or not.
-    If valid, it should be on an h x w image
-    """
-    return x >=0 and x < w and y >= 0 and y < h;
-    
-
-    
-def decode_image_by_join(pixel_scores, link_scores, 
-                 pixel_conf_threshold, link_conf_threshold):
-    pixel_mask = pixel_scores >= pixel_conf_threshold
-    link_mask = link_scores >= link_conf_threshold
-    points = zip(*np.where(pixel_mask))
-    h, w = np.shape(pixel_mask)
-    group_mask = dict.fromkeys(points, -1)
-    def find_parent(point):
-        return group_mask[point]
-        
-    def set_parent(point, parent):
-        group_mask[point] = parent
-        
-    def is_root(point):
-        return find_parent(point) == -1
-    
-    def find_root(point):
-        root = point
-        update_parent = False
-        while not is_root(root):
-            root = find_parent(root)
-            update_parent = True
-        
-        # for acceleration of find_root
-        if update_parent:
-            set_parent(point, root)
-            
-        return root
-        
-    def join(p1, p2):
-        root1 = find_root(p1)
-        root2 = find_root(p2)
-        
-        if root1 != root2:
-            set_parent(root1, root2)
-        
-    def get_all():
-        root_map = {}
-        def get_index(root):
-            if root not in root_map:
-                root_map[root] = len(root_map) + 1
-            return root_map[root]
-        
-        mask = np.zeros_like(pixel_mask, dtype = np.int32)
-        for point in points:
-            point_root = find_root(point)
-            bbox_idx = get_index(point_root)
-            mask[point] = bbox_idx
-        return mask
-    
-    # join by link
-    for point in points:
-        y, x = point
-        neighbours = get_neighbours(x, y)
-        for n_idx, (nx, ny) in enumerate(neighbours):
-            if is_valid_cord(nx, ny, w, h):
-#                 reversed_neighbours = get_neighbours(nx, ny)
-#                 reversed_idx = reversed_neighbours.index((x, y))
-                link_value = link_mask[y, x, n_idx]# and link_mask[ny, nx, reversed_idx]
-                pixel_cls = pixel_mask[ny, nx]
-                if link_value and pixel_cls:
-                    join(point, (ny, nx))
-    
-    mask = get_all()
-    return mask
-
diff --git a/pixel_link_env.txt b/pixel_link_env.txt
index d6a7a51..55c8161 100644
--- a/pixel_link_env.txt
+++ b/pixel_link_env.txt
@@ -32,7 +32,6 @@ dependencies:
   - backports.functools-lru-cache==1.5
   - bottle==0.12.13
   - cycler==0.10.0
-  - cython==0.28.2
   - enum34==1.1.6
   - kiwisolver==1.0.1
   - matplotlib==2.2.2