• Debargha Mukherjee's avatar
    Replace division in self-guided filter · 4be12628
    Debargha Mukherjee authored
    Replaces division with multiplication in self-guided
    filter.
    
    The guided filter requires computation of:
    n^2.s^2/(n^2.s^2 + n^2.e).
    This is now implemented by computation of n^2.s^2/n^2.e followed
    by using a lookup table for the function f(x) = x/(x+1).
    To compute n^2.s^2/n^2.e, we use an integer multiplication based
    implementation which becomes feasible since n^2.e can only
    take a few values and their corresponding multipliers can be
    pre-computed.
    There is also another divison by n, that is also integerized.
    
    Change-Id: Id7b81bbafead0b8f04a1853ec69b9dec423bb66a
    4be12628