Add note on assumed data range.

scikits/image/color/colorconv.py

@@ -133,6 +133,8 @@ def rgb2hsv(rgb):
 
     Notes
     -----
+    The conversion assumes an input data range of [0, 1] for all color components.
+
     Conversion between RGB and HSV color spaces results in some loss of
     precision, due to integer arithmetic and rounding [1]_.
 
@@ -205,6 +207,8 @@ def hsv2rgb(hsv):
 
     Notes
     -----
+    The conversion assumes an input data range of [0, 1] for all color components.
+
     Conversion between RGB and HSV color spaces results in some loss of
     precision, due to integer arithmetic and rounding [1]_.