# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1444408402 -7200
# Node ID 4d2d36f849415e17428408d92558d795086ce118
# Parent  e82caf5f5a8a4b887308e0b3272c81bc1ab4379f
Removed the square function, made saturation/desaturation options float-based.

diff -r e82caf5f5a8a -r 4d2d36f84941 optimiser.py
--- a/optimiser.py	Fri Oct 09 14:20:02 2015 +0200
+++ b/optimiser.py	Fri Oct 09 18:33:22 2015 +0200
@@ -2,7 +2,7 @@
 
 """
 Convert and optimise images for display in an Acorn Electron MODE 1 variant
-with four colours per line but eight colours available for selection for each
+with four colours per line but eight colours available for selection on each
 line.
 
 Copyright (C) 2015 Paul Boddie <paul@boddie.org.uk>
@@ -35,8 +35,6 @@
 
 # Basic colour operations.
 
-def extra(x): return x
-
 def within(v, lower, upper):
     return min(max(v, lower), upper)
 
@@ -54,9 +52,6 @@
 def scale(rgb):
     return tuple(map(lambda x: x / 255.0, rgb))
 
-def square(srgb):
-    return tuple(map(lambda x: pow(x, 2), srgb))
-
 def invert(srgb):
     return tuple(map(lambda x: 1.0 - x, srgb))
 
@@ -69,7 +64,7 @@
     # Get the colour with components scaled from 0 to 1, plus the inverted
     # component values.
 
-    rgb = extra(scale(rgb))
+    rgb = scale(rgb)
     rgbi = invert(rgb)
     pairs = zip(rgbi, rgb)
 
@@ -302,11 +297,10 @@
 
 Options are...
 
--s - Saturate the input image (can be repeated)
--d - Desaturate the input image (can be repeated)
+-s - Saturate the input image (can be followed by a float, default 1.0)
+-d - Desaturate the input image (can be followed by a float, default 1.0)
 -D - Darken the input image (can be followed by a float, default 1.0)
 -B - Brighten the input image (can be followed by a float, default 1.0)
--2 - Square/diminish the bright corner colour contributions (experimental)
 
 -r - Rotate the input image clockwise
 -p - Generate a separate preview image
@@ -327,17 +321,11 @@
 
     # Preprocessing options that can be repeated for extra effect.
 
-    saturate = options.count("-s")
-    desaturate = options.count("-d")
+    saturate = get_float(options, "-s")
+    desaturate = get_float(options, "-d")
     darken = get_float(options, "-D")
     brighten = get_float(options, "-B")
 
-    # Experimental colour distribution modification.
-
-    use_square = "-2" in options
-    if use_square:
-        extra = square
-
     # General output options.
 
     rotate = "-r" in options
@@ -361,7 +349,7 @@
                 for x in range(0, width):
                     rgb = im.getpixel((x, y))
                     if saturate or desaturate:
-                        rgb = saturate_rgb(rgb, saturate and math.pow(0.5, saturate) or math.pow(2, desaturate))
+                        rgb = saturate_rgb(rgb, saturate and 0.5 / saturate or 2 * desaturate)
                     if darken or brighten:
                         rgb = amplify_rgb(rgb, brighten and 0.5 / brighten or 2 * darken)
                     im.putpixel((x, y), rgb)