add interpolate_function

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

2 files changed, 31 insertions, 1 deletions

diff --git a/info/blueshift.texinfo b/info/blueshift.texinfo
index 8433a6b..ac2ab8c 100644
--- a/info/blueshift.texinfo
+++ b/info/blueshift.texinfo
@@ -1537,7 +1537,8 @@ by invoking them.
 @section Interpolation
 
 ICC profiles and curves that have beens turned
-into functions with @code{functionise} have lower
+into functions with @code{functionise}, or curves
+read from the current adjustments, have lower
 input resolution that the input they receive;
 to compensate for this, nearest-neighbour
 interpolation is used. If you want to better
@@ -1574,6 +1575,16 @@ is the same for the original curves and the
 scaled up curves. It is recommended to
 use the order: red, green and blue.
 
+However, often these lookup tables are
+oftern turned in to functions. To interpolate
+a function, you can use the function
+@code{interpolate_function}, it takes
+two arguments: the function that applies
+adjustments from a lookup table, and
+a function that interpolates a lookup
+table trio. It returns a function that
+applies the interpolated lookup table.
+
 
 
 @node Configuration examples
diff --git a/src/interpolation.py b/src/interpolation.py
index f5acba3..9039c11 100644
--- a/src/interpolation.py
+++ b/src/interpolation.py
@@ -17,6 +17,7 @@
 
 # This module contains interpolation functions.
 
+from aux import *
 from curve import *
 
 
@@ -188,3 +189,21 @@ def eliminate_halos(r, g, b, R, G, B):
                 # and replace the local partition with the linear interpolation.
                 large[X1 : X2 + 1] = linear[ci][X1 : X2 + 1]
 
+
+def interpolate_function(function, interpolator):
+    '''
+    Interpolate a function that applies adjustments from a lookup table
+    
+    @param   function:()→void                                 The function that applies the adjustments
+    @param   interpolator:(list<float>{3})?→[list<float>{3}]  Function that interpolates lookup tables
+    @return  :()→void                                         `function` interpolated
+    '''
+    if interpolator is None:
+        return function
+    stored = store()
+    start_over()
+    function()
+    rc = functionise(interpolator(*store()))
+    restore(stored)
+    return rc
+