From 391e9761571ebd486e2ff7784b0a64a964580ebe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20Sch=C3=B6nberger?= <jschoenberger@demuc.de>
Date: Wed, 31 Jul 2013 19:24:18 +0200
Subject: [PATCH] Add specific branch for the percentile p0 = 0 case

---
 skimage/filter/rank/percentile_cy.pyx | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/skimage/filter/rank/percentile_cy.pyx b/skimage/filter/rank/percentile_cy.pyx
index ffa5e1b0..8fad59c5 100644
--- a/skimage/filter/rank/percentile_cy.pyx
+++ b/skimage/filter/rank/percentile_cy.pyx
@@ -161,11 +161,15 @@ cdef inline double _kernel_percentile(Py_ssize_t* histo, double pop, dtype_t g,
     cdef Py_ssize_t sum = 0
 
     if pop:
-        for i in range(max_bin):
-            sum += histo[i]
-            if sum >= p0 * pop:
-                break
-
+        if p0 == 0:  # make sure p0 == 0 returns the minimum filter
+            for i in range(max_bin):
+                if histo[i]:
+                    break
+        else:
+            for i in range(max_bin):
+                sum += histo[i]
+                if sum >= p0 * pop:
+                    break
         return i
     else:
         return 0