diff --git a/bg_construct.png b/bg_construct.png
new file mode 100644
index 0000000..4b6f801
Binary files /dev/null and b/bg_construct.png differ
diff --git a/img2pa.py b/img2pa.py
index 9317ceb..f18bbf1 100644
--- a/img2pa.py
+++ b/img2pa.py
@@ -1,2 +1,11 @@
-from PIL import image
+from PIL import Image
+import os
 
+dir = os.getcwd()
+img = Image.open(dir+'/bg_construct.png')
+
+for i in range(0, 251, 25): #for multiple iteration
+    thresh = i
+    fn = lambda x : 255 if x > thresh else 0
+    r = img.convert('L').point(fn, mode='1')
+    r.save(dir + '/bg_const_bw_' + str(i) + '.png')
\ No newline at end of file