From 3340d0612dbc7dc8dfd8273346e01be467fbecff Mon Sep 17 00:00:00 2001
From: Tony S Yu <tsyu80@gmail.com>
Date: Sat, 28 Jul 2012 14:38:46 -0400
Subject: [PATCH] BUG: Fix scaling when setting default slider value.

---
 skimage/viewer/widgets/core.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/skimage/viewer/widgets/core.py b/skimage/viewer/widgets/core.py
index 826dc4f5..31d177ef 100644
--- a/skimage/viewer/widgets/core.py
+++ b/skimage/viewer/widgets/core.py
@@ -81,9 +81,11 @@ class Slider(BaseWidget):
         # divide slider into 1000 discrete values
         slider_min = 0
         slider_max = 1000
-        if value is None:
-            value = 500
         scale = float(high - low) / slider_max
+        if value is None:
+            slider_value = 500
+        else:
+            slider_value = (value - low) / scale
         self._scale = scale
         self._low = low
         self._high = high
@@ -106,7 +108,7 @@ class Slider(BaseWidget):
 
         self.slider = QtGui.QSlider(orientation_slider)
         self.slider.setRange(slider_min, slider_max)
-        self.slider.setValue(value)
+        self.slider.setValue(slider_value)
         if update_on == 'move':
             self.slider.valueChanged.connect(self._on_slider_changed)
         elif update_on == 'release':