Improved lay-out.

Demo/sgi/video/colorsys.py

@@ -1,20 +1,30 @@
+# Conversions between RGB and YIQ color spaces.
 #
-# Module color - do color conversions
-#
+# R, G, B are amounts of Red, Green and Blue;
+# Y, I, Q are intensity (Y) and two difference signals (I, Q).
 
-def rgb_to_yiq(r,g,b):
-    y = 0.30*r + 0.59*g + 0.11*b
-    i = 0.60*r - 0.28*g - 0.32*b
-    q = 0.21*r - 0.52*g + 0.31*b
-    return (y,i,q)
-def yiq_to_rgb(y,i,q):
-    r = y + 0.948262*i + 0.624013*q
-    g = y - 0.276066*i - 0.639810*q
-    b = y - 1.105450*i + 1.729860*q
-    if r < 0.0: r = 0.0
-    if g < 0.0: g = 0.0
-    if b < 0.0: b = 0.0
-    if r > 1.0: r = 1.0
-    if g > 1.0: g = 1.0
-    if b > 1.0: b = 1.0
-    return (r,g,b)
+
+# Convert a (R, G, B) triple to (Y, I, Q).
+# Scale is arbitrary (output uses the same scale as input).
+
+def rgb_to_yiq(r, g, b):
+	y = 0.30*r + 0.59*g + 0.11*b
+	i = 0.60*r - 0.28*g - 0.32*b
+	q = 0.21*r - 0.52*g + 0.31*b
+	return y, i, q
+
+
+# Convert a (Y, I, Q) triple to (R, G, B).
+# Input and output values are in the interval [0.0 ... 1.0].
+
+def yiq_to_rgb(y, i, q):
+	r = y + 0.948262*i + 0.624013*q
+	g = y - 0.276066*i - 0.639810*q
+	b = y - 1.105450*i + 1.729860*q
+	if r < 0.0: r = 0.0
+	if g < 0.0: g = 0.0
+	if b < 0.0: b = 0.0
+	if r > 1.0: r = 1.0
+	if g > 1.0: g = 1.0
+	if b > 1.0: b = 1.0
+	return r, g, b