# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444483011 -7200
# Node ID e0fe30d7b8b13f2108857d313baa3dae2a1235fd
# Parent  b147df07482fe86e9479a8979ba3e17de41fb577
Perform processing giving identical results only once.

diff -r b147df07482f -r e0fe30d7b8b1 optimiser.py
--- a/optimiser.py	Sat Oct 10 14:57:16 2015 +0200
+++ b/optimiser.py	Sat Oct 10 15:16:51 2015 +0200
@@ -58,6 +58,9 @@
     r, g, b = srgb
     return 1.0 - r, 1.0 - g, 1.0 - b
 
+scaled_corners = map(scale, corners)
+zipped_corners = zip(corners, scaled_corners)
+
 # Colour distribution functions.
 
 def combination(rgb):
@@ -76,8 +79,8 @@
     # input colour.
 
     d = []
-    for corner in corners:
-        rs, gs, bs = scale(corner)
+    for corner, scaled in zipped_corners:
+        rs, gs, bs = scaled
 
         # Obtain inverted channel values where corner channels are low;
         # obtain original channel values where corner channels are high.
@@ -95,6 +98,9 @@
     r, g, b = rgb
     return rgb, restore(invert(scale(rgb)))
 
+bases = [(0, 0, 0), (255, 0, 0), (0, 255, 0), (0, 0, 255)]
+base_complements = map(complements, bases)
+
 def balance(d):
 
     """
@@ -103,7 +109,7 @@
     """
 
     d = dict([(value, f) for f, value in d])
-    for primary, secondary in map(complements, [(0, 0, 0), (255, 0, 0), (0, 255, 0), (0, 0, 255)]):
+    for primary, secondary in base_complements:
         common = min(d[primary], d[secondary])
         d[primary] -= common
         d[secondary] -= common