From fad2813dd8e6fb50e6552a5fbadf1b5e9635f267 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Sch=C3=B6nberger?= <hannesschoenberger@gmail.com>
Date: Sat, 6 Oct 2012 18:01:40 +0200
Subject: [PATCH] Fix callable test in LPI filter

---
 skimage/filter/lpi_filter.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/skimage/filter/lpi_filter.py b/skimage/filter/lpi_filter.py
index 3826f5e7..2af74d7a 100644
--- a/skimage/filter/lpi_filter.py
+++ b/skimage/filter/lpi_filter.py
@@ -75,7 +75,7 @@ class LPIFilter2D(object):
         >>> filter = LPIFilter2D(filt_func)
 
         """
-        if impulse_response is None:
+        if not callable(impulse_response):
             raise ValueError("Impulse response must be a callable.")
 
         self.impulse_response = impulse_response