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Nohalo: much better minmod -> shorter and faster

This commit is contained in:
Nicolas Robidoux 2009-03-15 02:30:57 +00:00
parent d028a2cc52
commit 97cb89d288
1 changed files with 69 additions and 136 deletions
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205
libsrc/resample/nohalo.cpp
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@ -40,7 +40,7 @@
*/
/* Hacked for vips by J. Cupitt, 20/1/09
* Tweaks by N. Robidoux, 03/3/09
* Tweaks by N. Robidoux and J. Cupitt 5-15/03/09
*/
/*
@ -234,14 +234,17 @@
* function is discontinuous on the right instead of the left.
*/
#define FAST_PSEUDO_FLOOR(x) ( (int)(x) - ( (x) < 0. ) )
/*
* Alternative (if conditional move is fast and correctly identified
* by the compiler):
*
* #define FAST_PSEUDO_FLOOR(x) ( (x)>=0 ? (int)(x) : (int)(x)-1 )
*/
#define FAST_MIN(a,b) ( (a) <= (b) ? (a) : (b) )
/*
* FAST_MINMOD is an implementation of the minmod function which only
* needs two conditional moves. (Most implementations need at least
* three branches.) In the Nohalo code, the square of the first
* argument is used in two different minmod computations. The product
* is also precomputed to keep it out of branching way. (Nicolas: I
* think that this may be the first two branch minmod.)
*/
#define FAST_MINMOD(a,b,ab,aa) \
( (ab)>=0. ? ( (ab)-(aa)>=0. ? (a) : (b) ) : 0. )
#define VIPS_TYPE_INTERPOLATE_NOHALO \
(vips_interpolate_nohalo_get_type())
@ -356,145 +359,76 @@ nohalo_sharp_level_1(
const double troi_thr = qua_thr - tre_thr;
/*
* Useful later:
* Products useful for minmod:
*/
const double dos_two_plus_dos_thr = dos_two + dos_thr;
const double dos_two_plus_tre_two = dos_two + tre_two;
const double deux_dos_prem_dos = deux_dos * prem_dos;
const double deux_dos_deux_dos = deux_dos * deux_dos;
const double deux_dos_troi_dos = deux_dos * troi_dos;
/*
* Dos:
*/
const double half_sign_prem_dos = prem_dos >= 0. ? .5 : -.5;
const double half_sign_deux_dos = deux_dos >= 0. ? .5 : -.5;
const double half_sign_troi_dos = troi_dos >= 0. ? .5 : -.5;
/*
* Tre:
*/
const double half_sign_prem_tre = prem_tre >= 0. ? .5 : -.5;
const double half_sign_deux_tre = deux_tre >= 0. ? .5 : -.5;
const double half_sign_troi_tre = troi_tre >= 0. ? .5 : -.5;
/*
* Two:
*/
const double half_sign_prem_two = prem_two >= 0. ? .5 : -.5;
const double half_sign_deux_two = deux_two >= 0. ? .5 : -.5;
const double half_sign_troi_two = troi_two >= 0. ? .5 : -.5;
/*
* Thr:
*/
const double half_sign_prem_thr = prem_thr >= 0. ? .5 : -.5;
const double half_sign_deux_thr = deux_thr >= 0. ? .5 : -.5;
const double half_sign_troi_thr = troi_thr >= 0. ? .5 : -.5;
const double deux_two_prem_two = deux_two * prem_two;
const double deux_two_deux_two = deux_two * deux_two;
const double deux_two_troi_two = deux_two * troi_two;
/*
* Dos:
*/
const double half_abs_prem_dos = half_sign_prem_dos * prem_dos;
const double sign_dos_two_horizo = half_sign_prem_dos + half_sign_deux_dos;
const double half_abs_deux_dos = half_sign_deux_dos * deux_dos;
const double sign_dos_thr_horizo = half_sign_deux_dos + half_sign_troi_dos;
const double half_abs_troi_dos = half_sign_troi_dos * troi_dos;
/*
* Two:
*/
const double half_abs_prem_two = half_sign_prem_two * prem_two;
const double sign_dos_two_vertic = half_sign_prem_two + half_sign_deux_two;
const double half_abs_deux_two = half_sign_deux_two * deux_two;
const double sign_tre_two_vertic = half_sign_deux_two + half_sign_troi_two;
const double half_abs_troi_two = half_sign_troi_two * troi_two;
/*
* Tre:
*/
const double half_abs_prem_tre = half_sign_prem_tre * prem_tre;
const double sign_tre_two_horizo = half_sign_prem_tre + half_sign_deux_tre;
const double half_abs_deux_tre = half_sign_deux_tre * deux_tre;
const double sign_tre_thr_horizo = half_sign_deux_tre + half_sign_troi_tre;
const double half_abs_troi_tre = half_sign_troi_tre * troi_tre;
/*
* Thr:
*/
const double half_abs_prem_thr = half_sign_prem_thr * prem_thr;
const double sign_dos_thr_vertic = half_sign_prem_thr + half_sign_deux_thr;
const double half_abs_deux_thr = half_sign_deux_thr * deux_thr;
const double sign_tre_thr_vertic = half_sign_deux_thr + half_sign_troi_thr;
const double half_abs_troi_thr = half_sign_troi_thr * troi_thr;
const double deux_tre_prem_tre = deux_tre * prem_tre;
const double deux_tre_deux_tre = deux_tre * deux_tre;
const double deux_tre_troi_tre = deux_tre * troi_tre;
/*
* Useful later:
*/
const double tre_thr_minus_dos_two = deux_thr + deux_dos;
/*
* Dos:
*/
const double half_size_dos_two_horizo =
FAST_MIN( half_abs_prem_dos, half_abs_deux_dos );
const double half_size_dos_thr_horizo =
FAST_MIN( half_abs_troi_dos, half_abs_deux_dos );
/*
* Two:
*/
const double half_size_dos_two_vertic =
FAST_MIN( half_abs_prem_two, half_abs_deux_two );
const double half_size_tre_two_vertic =
FAST_MIN( half_abs_troi_two, half_abs_deux_two );
/*
* Tre:
*/
const double half_size_tre_two_horizo =
FAST_MIN( half_abs_prem_tre, half_abs_deux_tre );
const double half_size_tre_thr_horizo =
FAST_MIN( half_abs_troi_tre, half_abs_deux_tre );
/*
* Thr:
*/
const double half_size_dos_thr_vertic =
FAST_MIN( half_abs_prem_thr, half_abs_deux_thr );
const double half_size_tre_thr_vertic =
FAST_MIN( half_abs_troi_thr, half_abs_deux_thr );
const double deux_thr_prem_thr = deux_thr * prem_thr;
const double deux_thr_deux_thr = deux_thr * deux_thr;
const double deux_thr_troi_thr = deux_thr * troi_thr;
/*
* Compute the needed "right" (at the boundary between one input
* pixel areas) double resolution pixel value:
*/
const double two_times_dos_twothr =
dos_two_plus_dos_thr
dos_two + dos_thr
+
sign_dos_two_horizo * half_size_dos_two_horizo
-
sign_dos_thr_horizo * half_size_dos_thr_horizo;
.5
*
(
FAST_MINMOD( deux_dos, prem_dos, deux_dos_prem_dos, deux_dos_deux_dos )
-
FAST_MINMOD( deux_dos, troi_dos, deux_dos_troi_dos, deux_dos_deux_dos )
);
/*
* Compute the needed "down" double resolution pixel value:
*/
const double two_times_dostre_two =
dos_two_plus_tre_two
dos_two + tre_two
+
sign_dos_two_vertic * half_size_dos_two_vertic
-
sign_tre_two_vertic * half_size_tre_two_vertic;
.5
*
(
FAST_MINMOD( deux_two, prem_two, deux_two_prem_two, deux_two_deux_two )
-
FAST_MINMOD( deux_two, troi_two, deux_two_troi_two, deux_two_deux_two )
);
/*
* Compute the "diagonal" (at the boundary between thrr input
* pixel areas) double resolution pixel value:
*/
const double four_times_dostre_twothr =
tre_thr_minus_dos_two
deux_thr + deux_dos
+
sign_tre_two_horizo * half_size_tre_two_horizo
-
sign_tre_thr_horizo * half_size_tre_thr_horizo
.5
*
(
FAST_MINMOD( deux_tre, prem_tre, deux_tre_prem_tre, deux_tre_deux_tre )
-
FAST_MINMOD( deux_tre, troi_tre, deux_tre_troi_tre, deux_tre_deux_tre )
+
FAST_MINMOD( deux_thr, prem_thr, deux_thr_prem_thr, deux_thr_deux_thr )
-
FAST_MINMOD( deux_thr, troi_thr, deux_thr_troi_thr, deux_thr_deux_thr )
)
+
sign_dos_thr_vertic * half_size_dos_thr_vertic
-
sign_tre_thr_vertic * half_size_tre_thr_vertic
+
two_times_dos_twothr
+
two_times_dostre_two;
two_times_dos_twothr + two_times_dostre_two;
/*
* Return the newly computed double density values:
* Return the first newly computed double density values:
*/
*r1 = two_times_dos_twothr;
*r2 = two_times_dostre_two;
@ -607,6 +541,14 @@ vips_interpolate_nohalo_interpolate( VipsInterpolate *interpolate,
double absolute_x,
double absolute_y )
{
/*
* VIPS versions of Nicolas's pixel addressing values. Double bands for
* complex images.
*/
const int bands_actual = in->im->Bands;
const int lskip = IM_REGION_LSKIP( in ) / IM_IMAGE_SIZEOF_ELEMENT( in->im );
const int bands =
( im_iscomplex( in->im ) ? 2 * bands_actual : bands_actual );
/*
* floor's surrogate FAST_PSEUDO_FLOOR is used to make sure that the
* transition through 0 is smooth. If it is known that absolute_x
@ -615,9 +557,15 @@ vips_interpolate_nohalo_interpolate( VipsInterpolate *interpolate,
* any function which agrees with floor for non-integer values, and
* picks one of the two possibilities for integer values, can be
* used. FAST_PSEUDO_FLOOR fits the bill.
*
* Then, x is the x-coordinate of the sampling point relative to the
* position of the center of the convex hull of the 2x2 block of
* closest pixels. Similarly for y. Range of values: [-.5,.5).
*/
const int ix = FAST_PSEUDO_FLOOR (absolute_x);
const int iy = FAST_PSEUDO_FLOOR (absolute_y);
const double relative_y = ( absolute_y - .5 ) - iy;
const int ix = FAST_PSEUDO_FLOOR (absolute_x);
const double relative_x = ( absolute_x - .5 ) - ix;
/*
* Move the pointer to (the first band of) the top/left pixel
@ -626,21 +574,6 @@ vips_interpolate_nohalo_interpolate( VipsInterpolate *interpolate,
*/
const PEL * restrict p = (PEL *) IM_REGION_ADDR( in, ix, iy );
/*
* VIPS versions of Nicolas's pixel addressing values. Double bands for
* complex images.
*/
const int bands = in->im->Bands * (im_iscomplex( in->im ) ? 2 : 1);
const int lskip = IM_REGION_LSKIP( in ) / IM_IMAGE_SIZEOF_ELEMENT( in->im );
/*
* x is the x-coordinate of the sampling point relative to the
* position of the center of the convex hull of the 2x2 block of
* closest pixels. Similarly for y. Range of values: [-.5,.5).
*/
const double relative_x = absolute_x - ix - .5;
const double relative_y = absolute_y - iy - .5;
#define CALL( T, inter ) \
nohalo_sharp_level_1_ ## inter<T>( out, \
p, \