# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1443894793 -7200
# Node ID 7437f3302bc870204ea87eecb2c05000c9c4b9b4
# Parent  baa08ae98f2e88bd6a5d30e5980b768a0b0b5bb3
Experiment with different complementary pairs when reducing contributions.

diff -r baa08ae98f2e -r 7437f3302bc8 optimiser.py
--- a/optimiser.py	Sat Oct 03 19:08:11 2015 +0200
+++ b/optimiser.py	Sat Oct 03 19:53:13 2015 +0200
@@ -47,13 +47,35 @@
     return rgb, restore(invert(scale(rgb)))
 
 def balance(d):
+
+    # Find the dominant complementary pair.
+
+    d.sort(reverse=True)
+    found = set()
+    for f, value in d:
+        value, complement = complements(value)
+        if value in found or complement in found:
+            found = [value, complement]
+            break
+        else:
+            found.add(value)
+
+    # Remove the dominant primary (or black) from the list of colours.
+
+    colours = [(0, 0, 0), (255, 0, 0), (0, 255, 0), (0, 0, 255)]
+    if found[0] in colours:
+        colours.remove(found[0])
+    else:
+        colours.remove(found[1])
+
     d = dict([(value, f) for f, value in d])
-    for primary, secondary in map(complements, [(255, 0, 0), (0, 255, 0), (0, 0, 255)]):
+
+    for primary, secondary in map(complements, colours):
         common = min(d[primary], d[secondary])
         d[primary] -= common
         d[secondary] -= common
-        d[(0, 0, 0)] += common
-        d[(255, 255, 255)] += common
+        d[found[0]] += common
+        d[found[1]] += common
     return [(f, value) for value, f in d.items()]
 
 def combine(d):