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lbb resampler speed tweaks

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This commit is contained in:
Nicolas Robidoux 2010-05-30 19:52:25 +00:00
parent beea655158
commit 101b42b8c2
1 changed files with 23 additions and 32 deletions
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55
libvips/resample/lbb.cpp
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@ -537,46 +537,37 @@ lbbicubic( const double c00,
const double quad_d2zdxdy11 = LBB_MIN( quad_d2zdxdy11iiii, fourth_limit11);
/*
* Four times the part of the result which only uses cross
* derivatives:
* Part of the result which does not need derivatives:
*/
const double newval3 = c00dxdy * quad_d2zdxdy00
+
c10dxdy * quad_d2zdxdy10
+
c01dxdy * quad_d2zdxdy01
+
c11dxdy * quad_d2zdxdy11;
const double newval1 =
( c00 * dos_two + c10 * dos_thr )
+
( c01 * tre_two + c11 * tre_thr );
/*
* Twice the part of the result which only needs first derivatives.
*/
const double newval2 = c00dx * dble_dzdx00
+
c10dx * dble_dzdx10
+
c01dx * dble_dzdx01
+
c11dx * dble_dzdx11
+
c00dy * dble_dzdy00
+
c10dy * dble_dzdy10
+
c01dy * dble_dzdy01
+
c11dy * dble_dzdy11;
const double newval2 =
(
( c00dx * dble_dzdx00 + c10dx * dble_dzdx10 )
+
( c01dx * dble_dzdx01 + c11dx * dble_dzdx11 )
)
+
(
( c00dy * dble_dzdy00 + c10dy * dble_dzdy10 )
+
( c01dy * dble_dzdy01 + c11dy * dble_dzdy11 )
);
/*
* Part of the result which does not need derivatives:
* Four times the part of the result which only uses cross
* derivatives:
*/
const double newval1 = c00 * dos_two
+
c10 * dos_thr
+
c01 * tre_two
+
c11 * tre_thr;
const double newval3 =
( c00dxdy * quad_d2zdxdy00 + c10dxdy * quad_d2zdxdy10 )
+
( c01dxdy * quad_d2zdxdy01 + c11dxdy * quad_d2zdxdy11 );
const double newval = newval1 + .5 * newval2 + .25 * newval3;