diff --git a/skimage/filter/edges.py b/skimage/filter/edges.py
index cfc0b15c..7a70f00b 100644
--- a/skimage/filter/edges.py
+++ b/skimage/filter/edges.py
@@ -1,3 +1,14 @@
+"""
+
+Sobel and Prewitt filters originally part of CellProfiler, code licensed under
+both GPL and BSD licenses.
+Website: http://www.cellprofiler.org
+Copyright (c) 2003-2009 Massachusetts Institute of Technology
+Copyright (c) 2009-2011 Broad Institute
+All rights reserved.
+Original author: Lee Kamentsky
+
+"""
 import numpy as np
 from skimage import img_as_float
 from scipy.ndimage import convolve, binary_erosion, generate_binary_structure