Fix numerical precision issue in colour.difference.delta_E_CIE1994 …

…definition.

Closes #1206.

colour/difference/delta_e.py

@@ -45,7 +45,7 @@
 
 from colour.algebra import euclidean_distance
 from colour.hints import ArrayLike, NDArrayFloat
-from colour.utilities import as_float, to_domain_100, tsplit
+from colour.utilities import as_float, to_domain_100, tsplit, zeros
 from colour.utilities.documentation import (
     DocstringFloat,
     is_documentation_building,
@@ -225,7 +225,9 @@ def delta_E_CIE1994(
     delta_A = a_1 - a_2
     delta_B = b_1 - b_2
 
-    delta_H = np.sqrt(delta_A**2 + delta_B**2 - delta_C**2)
+    radical = delta_A**2 + delta_B**2 - delta_C**2
+    delta_H = zeros(radical.shape)
+    delta_H[radical > 0] = np.sqrt(radical[radical > 0])
 
     L = (delta_L / (k_L * s_L)) ** 2
     C = (delta_C / (k_C * s_C)) ** 2