From c7e8e1ba7042ab475ec1ad118ddf41df136360c9 Mon Sep 17 00:00:00 2001
From: Thomas Boggs <thomas.boggs@gmail.com>
Date: Thu, 23 Apr 2015 00:00:11 -0400
Subject: [PATCH] Allow interpolated colors in default color scale [fixes #26].

* graphics/color_scale.py (HypercubeWindow.load_textures): Use
  256 colors in the color scale.
* graphics/colorscale.py (create_default_color_scale): Accept optional
  `ntics` argument to specirfy total number of colors.
---
 spectral/graphics/colorscale.py | 18 +++++++++++++++---
 spectral/graphics/hypercube.py  |  4 ++--
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/spectral/graphics/colorscale.py b/spectral/graphics/colorscale.py
index def3512..8e6185d 100644
--- a/spectral/graphics/colorscale.py
+++ b/spectral/graphics/colorscale.py
@@ -132,8 +132,16 @@ def set_range(self, min, max):
         self.span = max - min
 
 
-def create_default_color_scale():
-    '''Returns a black-blue-green-red-white color scale.'''
+def create_default_color_scale(ntics=0):
+    '''Returns a black-blue-green-red-yellow-white color scale.
+
+    Arguments:
+
+            `ntics` (integer):
+
+                Total number of colors in the scale. If this value is 0, no
+                interpolated colors will be used.
+    '''
     from numpy import array
     mycolors = array([[0, 0, 0],
                       [0, 0, 255],
@@ -141,8 +149,12 @@ def create_default_color_scale():
                       [255, 0, 0],
                       [255, 255, 0],
                       [255, 255, 255]])
+
+    if ntics != 0 and ntics < len(mycolors):
+        raise ValueError('Any non-zero value of `ntics` must be greater than'
+                         ' {}.'.format(len(mycolors)))
     levels = array([0., 10., 20., 30., 40., 50.])
-    scale = ColorScale(levels, mycolors)
+    scale = ColorScale(levels, mycolors, ntics)
     return scale
 
 default_color_scale = create_default_color_scale()
diff --git a/spectral/graphics/hypercube.py b/spectral/graphics/hypercube.py
index 3bade20..770b229 100644
--- a/spectral/graphics/hypercube.py
+++ b/spectral/graphics/hypercube.py
@@ -227,14 +227,14 @@ def load_textures(self):
         import spectral
         from spectral.spectral import Image
         from . import graphics
-        from spectral.graphics.colorscale import default_color_scale
+        from spectral.graphics.colorscale import create_default_color_scale
 
         global DEFAULT_TEXTURE_SIZE
 
         if 'scale' in self.kwargs:
             scale = self.kwargs['scale']
         else:
-            scale = default_color_scale
+            scale = create_default_color_scale(256)
 
         data = self.hsi
         s = data.shape