doc

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 16 insertions, 24 deletions

diff --git a/src/colour.py b/src/colour.py
index e0cc490..e2bbc01 100644
--- a/src/colour.py
+++ b/src/colour.py
@@ -15,6 +15,9 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# This module implements functions from convertions between colour spaces
+# and comparion of colours
+
 
 def linear_to_standard(*colour):
     '''
@@ -57,11 +60,8 @@ def ciexyz_to_ciexyy(X, Y, Z):
     @param   Z:float                 The Z parameter
     @return  :[float, float, float]  The x, y and Y parameters
     '''
-    if X + Y + Z == 0:
-        return [0, 0, 0]
-    y = Y / (X + Y + Z)
-    x = X / (X + Y + Z)
-    return [x, y, Y]
+    s = X + Y + Z
+    return [X / s, Y / s, Y] if not s == 0 else [0, 0, 0]
 
 
 def matrix_mul_vector(matrix, vector):
@@ -78,6 +78,9 @@ def matrix_mul_vector(matrix, vector):
 ciexyz_to_linear_matrix = [[ 3.240450, -1.537140, -0.4985320],
                            [-0.969266,  1.876010,  0.0415561],
                            [0.0556434, -0.204026,  1.0572300]]
+'''
+Multiplication matrix to convert from CIE xyY to linear RGB
+'''
 
 def ciexyz_to_linear(X, Y, Z):
     '''
@@ -94,6 +97,9 @@ def ciexyz_to_linear(X, Y, Z):
 linear_to_ciexyz_matrix = [[0.4124564, 0.3575761, 0.1804375],
                            [0.2126729, 0.7151522, 0.0721750],
                            [0.0193339, 0.1191920, 0.9503041]]
+'''
+Multiplication matrix to convert from linear RGB to CIE xyY
+'''
 
 def linear_to_ciexyz(r, g, b):
     '''
@@ -118,10 +124,7 @@ def srgb_to_ciexyy(r, g, b):
     '''
     if r == g == b == 0:
         return (0.312857, 0.328993, 0)
-    rc = standard_to_linear(r, g, b)
-    rc = linear_to_ciexyz(*rc)
-    rc = ciexyz_to_ciexyy(*rc)
-    return rc
+    return ciexyz_to_ciexyy(*linear_to_ciexyz(*standard_to_linear(r, g, b)))
 
 
 def ciexyy_to_srgb(x, y, Y):
@@ -133,10 +136,7 @@ def ciexyy_to_srgb(x, y, Y):
     @param   Y:float                 The Y parameter
     @return  :[float, float, float]  The red, green and blue components
     '''
-    rc = ciexyy_to_ciexyz(x, y, Y)
-    rc = ciexyz_to_linear(*rc)
-    rc = linear_to_standard(*rc)
-    return rc
+    return linear_to_standard(*ciexyz_to_linear(*ciexyy_to_ciexyz(x, y, Y)))
 
 
 def ciexyz_to_cielab(x, y, z):
@@ -170,10 +170,7 @@ def cielab_to_xiexyz(l, a, b):
     x = a / 500 + y
     z = y - b / 200
     f = lambda c : c ** 3 if c ** 3 > 0.00885642 else (c - 0.1379310) / (7.78 + 703 / 99900)
-    (x, y, z) = [f(c) for c in (x, y, z)]
-    x *= 0.95047
-    z *= 1.08883
-    return (x, y, z)
+    return [f(c) * m for c, m in zip((x, y, z), (0.95047, 1, 1.08883))]
 
 
 def delta_e(a, b):
@@ -184,11 +181,6 @@ def delta_e(a, b):
     @param   b:(float, float, float)  The second colour
     @return  :float                   The difference
     '''
-    a = standard_to_linear(*a)
-    b = standard_to_linear(*b)
-    a = linear_to_ciexyz(*a)
-    b = linear_to_ciexyz(*b)
-    a = ciexyz_to_cielab(*a)
-    b = ciexyz_to_cielab(*b)
-    return sum([(c1 - c2) ** 2 for c1, c2 in zip(a, b)]) ** 0.5
+    standard_to_cielab = lambda x : ciexyz_to_cielab(*linear_to_ciexyz(*standard_to_linear(*a)))
+    return sum([(c1 - c2) ** 2 for c1, c2 in zip(standard_to_cielab(a), standard_to_cielab(b))]) ** 0.5