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cleaned up sampler nohalo.cpp

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Nicolas Robidoux 2010-05-17 22:46:45 +00:00
parent 3963655a2d
commit eb716c4243
1 changed files with 56 additions and 75 deletions
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131
libvips/resample/nohalo.cpp
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@ -1,11 +1,12 @@
/* Nohalo (one level) subdivision followed by LBB (Locally Bounded Bicubic) interpolation /* Nohalo subdivision followed by LBB (Locally Bounded Bicubic)
* interpolation
* *
* N. Robidoux and C. Racette 05/11--05/16 * N. Robidoux and C. Racette 11/5--17/5/2009
* *
* N. Robidoux 01/4-29/5/09 * N. Robidoux 1/4-29/5/2009
* *
* N. Robidoux based on code by N. Robidoux, A. Turcotte and J. Cupitt * N. Robidoux based on code by N. Robidoux, A. Turcotte and J. Cupitt
* 27/01/10 * 27/1/2010
*/ */
/* /*
@ -36,8 +37,8 @@
*/ */
/* /*
* 2009-2010 (c) Nicolas Robidoux, Chantal Racette, Adam Turcotte and * 2009-2010 (c) Nicolas Robidoux, Chantal Racette, John Cupitt and
* John Cupitt * Adam Turcotte
* *
* Nicolas Robidoux thanks Geert Jordaens, Ralf Meyer, Øyvind Kolås, * Nicolas Robidoux thanks Geert Jordaens, Ralf Meyer, Øyvind Kolås,
* Minglun Gong, Eric Daoust and Sven Neumann for useful comments and * Minglun Gong, Eric Daoust and Sven Neumann for useful comments and
@ -51,9 +52,9 @@
* in part by a NSERC Discovery Grant awarded to Julien Dompierre. * in part by a NSERC Discovery Grant awarded to Julien Dompierre.
* *
* A. Turcotte's image resampling research and programming funded in * A. Turcotte's image resampling research and programming funded in
* part by a Google Summer of Code 2010 award awarded to GIMP (Gnu * part by an NSERC Alexander Graham Bell Canada Graduate Scholarhip
* Image Manipulation Program) and by an NSERC Alexander Graham Bell * awarded to him and by a Google Summer of Code 2010 award awarded to
* Canada Graduate Scholarhip awarded to him. * GIMP (Gnu Image Manipulation Program).
*/ */
/* /*
@ -69,6 +70,9 @@
* oblique lines without undesirable side-effects. In particular, * oblique lines without undesirable side-effects. In particular,
* without much blurring and with absolutely no added haloing. * without much blurring and with absolutely no added haloing.
* *
* In this code, one Nohalo subdivision is performed. The
* interpolation is finished with LBB (Locally Bounded Bicubic).
*
* Key properties: * Key properties:
* *
* ======================= * =======================
@ -111,24 +115,6 @@
* Nohalo is a local method * Nohalo is a local method
* ======================== * ========================
* *
* The value of the reconstructed intensity surface at any point
* depends on the values of (at most) 19 nearby input values. An
* explanatory diagram is found below.
*
* ===========================================================
* When level = infinity, nohalo's intensity surface is smooth
* ===========================================================
*
* It is conjectured that the intensity surface is infinitely
* differentiable. Consequently, "Mach banding" (primarily caused by
* sharp "ridges" in the reconstructed intensity surface and
* particularly noticeable, for example, when using bilinear
* resampling) is (essentially) absent, even at high magnifications,
* WHEN THE LEVEL IS HIGH (more or less when 2^(level+1) is at least
* the largest local magnification factor, which means that the level
* 1 nohalo does not show much Mach banding up to a magnification of
* about 4).
*
* =============================== * ===============================
* Nohalo is second order accurate * Nohalo is second order accurate
* =============================== * ===============================
@ -162,7 +148,7 @@
* Weaknesses of nohalo * Weaknesses of nohalo
* ==================== * ====================
* *
* In some cases, the first level nonlinear computation is wasted: * In some cases, the initial subdivision computation is wasted:
* *
* If a region is bichromatic, the nonlinear component of the level 1 * If a region is bichromatic, the nonlinear component of the level 1
* nohalo is zero in the interior of the region, and consequently * nohalo is zero in the interior of the region, and consequently
@ -170,18 +156,6 @@
* bilinear, or use a higher level (quality) setting. (There is no * bilinear, or use a higher level (quality) setting. (There is no
* real harm in using nohalo when it boils down to bilinear if one * real harm in using nohalo when it boils down to bilinear if one
* does not mind wasting cycles.) * does not mind wasting cycles.)
*
* Low quality levels do NOT produce a continuously differentiable
* intensity surface:
*
* With a "finite" level is used (that is, in practice), the nohalo
* intensity surface is only continuous: there are gradient
* discontinuities because the "final interpolation step" is performed
* with bilinear. (Exception: if the "corner" image size convention is
* used and the magnification factor is 4, that is, if the resampled
* points sit exactly on the binary subdivided grid, then nohalo level
* 2 gives the same result as as level=infinity, and consequently the
* intensity surface can be treated as if smooth.)
*/ */
#ifdef HAVE_CONFIG_H #ifdef HAVE_CONFIG_H
@ -264,6 +238,17 @@ typedef struct _VipsInterpolateNohaloClass {
#define MINMOD(a,b,a_times_a,a_times_b) \ #define MINMOD(a,b,a_times_a,a_times_b) \
( (a_times_b)>=0. ? 1. : 0. ) * ( (a_times_b)<(a_times_a) ? (b) : (a) ) ( (a_times_b)>=0. ? 1. : 0. ) * ( (a_times_b)<(a_times_a) ? (b) : (a) )
#define LBB_ABS(x) ( ((x)>=0.) ? (x) : -(x) )
#define LBB_SIGN(x) ( ((x)>=0.) ? 1.0 : -1.0 )
/*
* MIN and MAX macros set up so that I can put the likely winner in
* the first argument (forward branch likely blah blah blah):
*/
#define LBB_MIN(x,y) ( ((x)<=(y)) ? (x) : (y) )
#define LBB_MAX(x,y) ( ((x)>=(y)) ? (x) : (y) )
static void inline static void inline
nohalo_subdivision (const double uno_two, nohalo_subdivision (const double uno_two,
const double uno_thr, const double uno_thr,
@ -304,10 +289,9 @@ nohalo_subdivision (const double uno_two,
double* restrict qua_fou_1) double* restrict qua_fou_1)
{ {
/* /*
* nohalo_subdivision calculates the missing ten double density * nohalo_subdivision calculates the missing twelve double density
* pixel values, and also returns the "already known" two, so that * pixel values, and also returns the "already known" four, so that
* the twelve values which make up the stencil of Nohalo level 1 are * the values which make up the stencil of LBB are available.
* available.
*/ */
/* /*
* THE STENCIL OF INPUT VALUES: * THE STENCIL OF INPUT VALUES:
@ -345,7 +329,7 @@ nohalo_subdivision (const double uno_two,
* *
* *
* The above input pixel values are the ones needed in order to make * The above input pixel values are the ones needed in order to make
* available to the second level the following first level values: * available the following values, needed by LBB:
* *
* uno_one_1 = uno_two_1 = uno_thr_1 = uno_fou_1 = * uno_one_1 = uno_two_1 = uno_thr_1 = uno_fou_1 =
* (ix-1/2,iy-1/2) (ix,iy-1/2) (ix+1/2,iy-1/2) (ix+1,iy-1/2) * (ix-1/2,iy-1/2) (ix,iy-1/2) (ix+1/2,iy-1/2) (ix+1,iy-1/2)
@ -368,8 +352,6 @@ nohalo_subdivision (const double uno_two,
* qua_one_1 = qua_two_1 = qua_thr_1 = qua_fou_1 = * qua_one_1 = qua_two_1 = qua_thr_1 = qua_fou_1 =
* (ix-1/2,iy+1) (ix,iy+1) (ix+1/2,iy+1) (ix+1,iy+1) * (ix-1/2,iy+1) (ix,iy+1) (ix+1/2,iy+1) (ix+1,iy+1)
* *
*
* to which LBB interpolation is then applied.
*/ */
/* /*
@ -607,7 +589,7 @@ nohalo_subdivision (const double uno_two,
.125 * ( dos_two_y + dos_thr_y - tre_two_y - tre_thr_y ); .125 * ( dos_two_y + dos_thr_y - tre_two_y - tre_thr_y );
/* /*
* Return level 1 stencil values: * Return the sixteen LBB stencil values:
*/ */
*uno_one_1 = val_uno_one_1; *uno_one_1 = val_uno_one_1;
*uno_two_1 = val_uno_two_1; *uno_two_1 = val_uno_two_1;
@ -700,15 +682,6 @@ nohalo_subdivision (const double uno_two,
* be the minimum over the 4x4. Similarly with the maxima.) * be the minimum over the 4x4. Similarly with the maxima.)
*/ */
#define LBB_ABS(x) ( ((x)>=0.) ? (x) : -(x) )
#define LBB_SIGN(x) ( ((x)>=0.) ? 1.0 : -1.0 )
/*
* MIN and MAX macros set up so that I can put the likely winner in
* the first argument (forward branch likely blah blah blah):
*/
#define LBB_MIN(x,y) ( ((x)<=(y)) ? (x) : (y) )
#define LBB_MAX(x,y) ( ((x)>=(y)) ? (x) : (y) )
static inline double static inline double
lbbicubic( const double c00, lbbicubic( const double c00,
const double c10, const double c10,
@ -1066,9 +1039,9 @@ lbbicubic( const double c00,
* this would allow code comments!---but we can't figure a clean way * this would allow code comments!---but we can't figure a clean way
* to do it. * to do it.
*/ */
#define NOHALO_INTER( inter ) \ #define NOHALO_INTER( inter ) \
template <typename T> static void inline \ template <typename T> static void inline \
nohalo_ ## inter( PEL* restrict pout, \ nohalo_ ## inter( PEL* restrict pout, \
const PEL* restrict pin, \ const PEL* restrict pin, \
const int bands, \ const int bands, \
const int lskip, \ const int lskip, \
@ -1079,9 +1052,11 @@ lbbicubic( const double c00,
\ \
const T* restrict in = (T *) pin; \ const T* restrict in = (T *) pin; \
\ \
\
const int sign_of_x_0 = 2 * ( x_0 >= 0. ) - 1; \ const int sign_of_x_0 = 2 * ( x_0 >= 0. ) - 1; \
const int sign_of_y_0 = 2 * ( y_0 >= 0. ) - 1; \ const int sign_of_y_0 = 2 * ( y_0 >= 0. ) - 1; \
\ \
\
const int shift_forw_1_pix = sign_of_x_0 * bands; \ const int shift_forw_1_pix = sign_of_x_0 * bands; \
const int shift_forw_1_row = sign_of_y_0 * lskip; \ const int shift_forw_1_row = sign_of_y_0 * lskip; \
\ \
@ -1120,9 +1095,6 @@ lbbicubic( const double c00,
const int cin_thr_shift = shift_forw_2_row; \ const int cin_thr_shift = shift_forw_2_row; \
const int cin_fou_shift = shift_forw_1_pix + shift_forw_2_row; \ const int cin_fou_shift = shift_forw_1_pix + shift_forw_2_row; \
\ \
const double x = ( 2 * sign_of_x_0 ) * x_0 - .5; \
const double y = ( 2 * sign_of_y_0 ) * y_0 - .5; \
\
\ \
const double xp1over2 = ( 2 * sign_of_x_0 ) * x_0; \ const double xp1over2 = ( 2 * sign_of_x_0 ) * x_0; \
const double xm1over2 = xp1over2 - 1.0; \ const double xm1over2 = xp1over2 - 1.0; \
@ -1169,6 +1141,7 @@ lbbicubic( const double c00,
const double twice_1mx_times_yp1over2 = twice1mx * yp1over2; \ const double twice_1mx_times_yp1over2 = twice1mx * yp1over2; \
const double twice_1px_times_yp1over2 = twice1px * yp1over2; \ const double twice_1px_times_yp1over2 = twice1px * yp1over2; \
\ \
\
const double c00 = \ const double c00 = \
four_times_1px_times_1py * xm1over2sq_times_ym1over2sq; \ four_times_1px_times_1py * xm1over2sq_times_ym1over2sq; \
const double c00dx = \ const double c00dx = \
@ -1205,8 +1178,10 @@ lbbicubic( const double c00,
const double c11dxdy = \ const double c11dxdy = \
xm1over2_times_ym1over2 * xp1over2sq_times_yp1over2sq; \ xm1over2_times_ym1over2 * xp1over2sq_times_yp1over2sq; \
\ \
\
int band = bands; \ int band = bands; \
\ \
\
do \ do \
{ \ { \
double uno_one, uno_two, uno_thr, uno_fou; \ double uno_one, uno_two, uno_thr, uno_fou; \
@ -1285,11 +1260,13 @@ lbbicubic( const double c00,
qua_two, \ qua_two, \
qua_thr, \ qua_thr, \
qua_fou ); \ qua_fou ); \
{\ \
const T result = to_ ## inter<T>( double_result ); \ { \
in++; \ const T result = to_ ## inter<T>( double_result ); \
*out++ = result; \ in++; \
} \ *out++ = result; \
} \
\
} while (--band); \ } while (--band); \
} }
@ -1298,13 +1275,15 @@ NOHALO_INTER( fptypes )
NOHALO_INTER( withsign ) NOHALO_INTER( withsign )
NOHALO_INTER( nosign ) NOHALO_INTER( nosign )
#define CALL( T, inter ) \
nohalo_ ## inter<T>( out, \ #define CALL( T, inter ) \
p, \ nohalo_ ## inter<T>( out, \
bands, \ p, \
lskip, \ bands, \
relative_x, \ lskip, \
relative_y ); relative_x, \
relative_y );
/* /*
* We need C linkage: * We need C linkage:
@ -1314,6 +1293,7 @@ G_DEFINE_TYPE( VipsInterpolateNohalo, vips_interpolate_nohalo,
VIPS_TYPE_INTERPOLATE ); VIPS_TYPE_INTERPOLATE );
} }
static void static void
vips_interpolate_nohalo_interpolate( VipsInterpolate* restrict interpolate, vips_interpolate_nohalo_interpolate( VipsInterpolate* restrict interpolate,
PEL* restrict out, PEL* restrict out,
@ -1414,7 +1394,8 @@ vips_interpolate_nohalo_class_init( VipsInterpolateNohaloClass *klass )
gobject_class->get_property = vips_object_get_property; gobject_class->get_property = vips_object_get_property;
object_class->nickname = "nohalo"; object_class->nickname = "nohalo";
object_class->description = _( "Edge sharpening resampler with halo reduction" ); object_class->description =
_( "Edge sharpening resampler with halo reduction" );
interpolate_class->interpolate = vips_interpolate_nohalo_interpolate; interpolate_class->interpolate = vips_interpolate_nohalo_interpolate;
interpolate_class->window_size = 5; interpolate_class->window_size = 5;