diff --git a/debian/copyright b/debian/copyright
index c2f29d7..4e79714 100644
--- a/debian/copyright
+++ b/debian/copyright
@@ -252,6 +252,19 @@
 Copyright: 2013, Samuel Mimram
 License: GPL-2+
 
+Files: src/filter/normaliz0r/*
+Copyright: 2017, Chungzuwalla
+License: GPL-2+
+
+Files: src/filter/premultiply/*
+Copyright: 2018, Dan Dennedy <dan@dennedy.org>
+License: GPL-2+
+
+Files: src/filter/elastic_scale/*
+Copyright: 2018, Matthias Schnöll (matthias.schnoell AT gmail.com)
+License: GPL-2+
+
+
 Files: debian/*
 Copyright: 2008-2009 Christian Marillat <marillat@debian.org>
  2009-2010 Luca Bigliardi <shammash@artha.org>