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| author | Mattias Andrée <maandree@operamail.com> | 2014-04-06 00:44:00 +0200 |
|---|---|---|
| committer | Mattias Andrée <maandree@operamail.com> | 2014-04-06 00:44:00 +0200 |
| commit | 2c10dfc7aa259ad0fd5f3eab8879e870e77fd667 (patch) | |
| tree | 62e844743d811dd3ba987d170cf1cb8fe71c9f88 /src | |
| parent | add cubic interpolation test, did not work out too well (diff) | |
| download | blueshift-2c10dfc7aa259ad0fd5f3eab8879e870e77fd667.tar.gz blueshift-2c10dfc7aa259ad0fd5f3eab8879e870e77fd667.tar.bz2 blueshift-2c10dfc7aa259ad0fd5f3eab8879e870e77fd667.tar.xz | |
m + fix cubic interpolation
Signed-off-by: Mattias Andrée <maandree@operamail.com>
Diffstat (limited to '')
| -rw-r--r-- | src/interpolation.py | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/src/interpolation.py b/src/interpolation.py index 0d16838..e81c93c 100644 --- a/src/interpolation.py +++ b/src/interpolation.py @@ -47,13 +47,14 @@ def linearly_interpolate_ramp(r, g, b): return (R, G, B) -def cubicly_interpolate_ramp(r, g, b): +def cubicly_interpolate_ramp(r, g, b, tension = 0): # TODO demo and document tension parameter ''' Interpolate ramps to the size of the output axes using cubic Hermite spline @param r:list<float> The red colour curves @param g:list<float> The green colour curves @param b:list<float> The blue colour curves + @param tension:float A [0, 1] value of the tension @return :(r:list<float>, g:list<float>, b:list<float>) The input parameters extended to sizes of `o_size`, or their original size, whatever is larger. ''' @@ -61,8 +62,8 @@ def cubicly_interpolate_ramp(r, g, b): R, G, B = C(r), C(g), C(b) # Basis functions h00 = lambda t : (1 + 2 * t) * (1 - t) ** 2 - h01 = lambda t : t * (1 - t) ** 2 - h10 = lambda t : t ** 2 * (3 - 2 * t) + h10 = lambda t : t * (1 - t) ** 2 + h01 = lambda t : t ** 2 * (3 - 2 * t) h11 = lambda t : t ** 2 * (t - 1) def tangent(values, index, last): ''' @@ -77,6 +78,8 @@ def cubicly_interpolate_ramp(r, g, b): if index == 0: return values[1] - values[0] if index == last: return values[last] - values[last - 1] return (values[index + 1] - values[index - 1]) / 2 + # Tension coefficent + c_ = 1 - tension # Interpolate each curve for small, large in ((r, R), (g, G), (b, B)): small_, large_ = len(small) - 1, len(large) - 1 @@ -90,7 +93,7 @@ def cubicly_interpolate_ramp(r, g, b): # Points pj, pk = small[j], small[k] # Tangents - mj, mk = tangent(small, j, small_), tangent(small, k, small_) + mj, mk = c_ * tangent(small, j, small_), c_ * tangent(small, k, small_) # Interpolation large[i] = h00(w) * pj + h10(w) * mj + h01(w) * pk + h11(w) * mk ## Check local monotonicity |