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reducehl3 is done

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sort of anyway, tinkering with optimization
This commit is contained in:
John Cupitt 2016-03-09 22:47:02 +00:00
parent dcd921d7bf
commit a26291a426
11 changed files with 803 additions and 6 deletions
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1
libvips/include/vips/Makefile.am
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@ -56,6 +56,7 @@ EXTRA_DIST = version.h.in internal.h enumtemplate
# we need absolute filenames here since this list appears in the src dir as
# well
vips_scan_headers = \
${top_srcdir}/libvips/include/vips/resample.h \
${top_srcdir}/libvips/include/vips/memory.h \
${top_srcdir}/libvips/include/vips/create.h \
${top_srcdir}/libvips/include/vips/foreign.h \

3
libvips/include/vips/enumtypes.h
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@ -6,6 +6,9 @@
G_BEGIN_DECLS
/* enumerations from "../../../libvips/include/vips/resample.h" */
GType vips_kernel_get_type (void) G_GNUC_CONST;
#define VIPS_TYPE_KERNEL (vips_kernel_get_type())
/* enumerations from "../../../libvips/include/vips/foreign.h" */
GType vips_foreign_flags_get_type (void) G_GNUC_CONST;
#define VIPS_TYPE_FOREIGN_FLAGS (vips_foreign_flags_get_type())

9
libvips/include/vips/resample.h
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@ -38,6 +38,15 @@
extern "C" {
#endif /*__cplusplus*/
typedef enum {
VIPS_KERNEL_NEAREST,
VIPS_KERNEL_LINEAR,
VIPS_KERNEL_CUBIC,
VIPS_KERNEL_LANCZOS2,
VIPS_KERNEL_LANCZOS3,
VIPS_KERNEL_LAST
} VipsKernel;
int vips_shrink( VipsImage *in, VipsImage **out,
double xshrink, double yshrink, ... )
__attribute__((sentinel));

1
libvips/iofuncs/Makefile.am
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@ -54,6 +54,7 @@ AM_CPPFLAGS = -I${top_srcdir}/libvips/include @VIPS_CFLAGS@ @VIPS_INCLUDES@
# we need absolute filenames here since this list appears in the header dir as
# well
vips_scan_headers = \
${top_srcdir}/libvips/include/vips/resample.h \
${top_srcdir}/libvips/include/vips/memory.h \
${top_srcdir}/libvips/include/vips/create.h \
${top_srcdir}/libvips/include/vips/foreign.h \

22
libvips/iofuncs/enumtypes.c
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@ -4,6 +4,28 @@
/* auto-generated enums for vips introspection */
#include <vips/vips.h>
/* enumerations from "../../libvips/include/vips/resample.h" */
GType
vips_kernel_get_type( void )
{
static GType etype = 0;
if( etype == 0 ) {
static const GEnumValue values[] = {
{VIPS_KERNEL_NEAREST, "VIPS_KERNEL_NEAREST", "nearest"},
{VIPS_KERNEL_LINEAR, "VIPS_KERNEL_LINEAR", "linear"},
{VIPS_KERNEL_CUBIC, "VIPS_KERNEL_CUBIC", "cubic"},
{VIPS_KERNEL_LANCZOS2, "VIPS_KERNEL_LANCZOS2", "lanczos2"},
{VIPS_KERNEL_LANCZOS3, "VIPS_KERNEL_LANCZOS3", "lanczos3"},
{VIPS_KERNEL_LAST, "VIPS_KERNEL_LAST", "last"},
{0, NULL, NULL}
};
etype = g_enum_register_static( "VipsKernel", values );
}
return( etype );
}
/* enumerations from "../../libvips/include/vips/foreign.h" */
GType
vips_foreign_flags_get_type( void )

2
libvips/resample/Makefile.am
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@ -11,7 +11,9 @@ libresample_la_SOURCES = \
shrinkv.c \
reduce.c \
reduceh.cpp \
reducehl3.cpp \
reducev.cpp \
reducevl3.cpp \
interpolate.c \
transform.c \
bicubic.cpp \

3
libvips/resample/presample.h
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@ -65,6 +65,9 @@ typedef struct _VipsResampleClass {
GType vips_resample_get_type( void );
int vips_reducehl3_get_points( VipsKernel kernel );
void vips_reducehl3_make_mask( VipsKernel kernel, double x, double *c );
#ifdef __cplusplus
}
#endif /*__cplusplus*/

421
libvips/resample/reducehl3.cpp Normal file
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@ -0,0 +1,421 @@
/* horizontal reduce by a float factor with lanczos3
*
* 29/1/16
* - from shrinkh.c
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include <vips/debug.h>
#include <vips/internal.h>
#include "presample.h"
#include "templates.h"
/**
* VipsKernel:
* @VIPS_KERNEL_NEAREST: nearest-neighbour
* @VIPS_KERNEL_LINEAR: linear interpolation
* @VIPS_KERNEL_CUBIC: cubic interpolation
* @VIPS_KERNEL_LANCZOS2: lanczos2 interpolation
* @VIPS_KERNEL_LANCZOS3: lanczos3 interpolation
*
* 1D resampling kernels.
*/
/* The max size of the vector we use.
*/
#define MAX_POINTS (6)
typedef struct _VipsReducehl3 {
VipsResample parent_instance;
double xshrink; /* Reduce factor */
/* The thing we use to make the kernel.
*/
VipsKernel kernel;
/* Number of points in kernel.
*/
int n_points;
/* Precalculated interpolation matrices. int (used for pel
* sizes up to short), and double (for all others). We go to
* scale + 1 so we can round-to-nearest safely.
*/
int matrixi[VIPS_TRANSFORM_SCALE + 1][MAX_POINTS];
double matrixf[VIPS_TRANSFORM_SCALE + 1][MAX_POINTS];
} VipsReducehl3;
typedef VipsResampleClass VipsReducehl3Class;
/* We need C linkage for this.
*/
extern "C" {
G_DEFINE_TYPE( VipsReducehl3, vips_reducehl3, VIPS_TYPE_RESAMPLE );
}
/* Get n points.
*/
int
vips_reducehl3_get_points( VipsKernel kernel )
{
switch( kernel ) {
case VIPS_KERNEL_NEAREST:
return( 1 );
case VIPS_KERNEL_LINEAR:
return( 2 );
case VIPS_KERNEL_CUBIC:
return( 4 );
case VIPS_KERNEL_LANCZOS2:
return( 4 );
case VIPS_KERNEL_LANCZOS3:
return( 6 );
default:
g_assert_not_reached();
return( 0 );
}
}
/* Calculate a mask.
*/
void
vips_reducehl3_make_mask( VipsKernel kernel, double x, double *c )
{
switch( kernel ) {
case VIPS_KERNEL_NEAREST:
c[0] = 1.0;
break;
case VIPS_KERNEL_LINEAR:
c[0] = x;
c[1] = 1.0 - x;
break;
case VIPS_KERNEL_CUBIC:
calculate_coefficients_catmull( x, c );
break;
case VIPS_KERNEL_LANCZOS2:
calculate_coefficients_lanczos( 2, x, c );
break;
case VIPS_KERNEL_LANCZOS3:
calculate_coefficients_lanczos( 3, x, c );
break;
default:
g_assert_not_reached();
break;
}
}
template <typename T, int max_value>
static void inline
reducehl3_unsigned_int_tab( VipsReducehl3 *reducehl3,
VipsPel *pout, const VipsPel *pin,
const int bands, const int * restrict cx )
{
T* restrict out = (T *) pout;
const T* restrict in = (T *) pin;
for( int z = 0; z < bands; z++ ) {
int sum;
sum = 0;
for( int i = 0; i < reducehl3->n_points; i++ )
sum += cx[i] * in[i * bands];
sum = unsigned_fixed_round( sum );
sum = VIPS_CLIP( 0, sum, max_value );
out[z] = sum;
in += 1;
}
}
static int
vips_reducehl3_gen( VipsRegion *out_region, void *seq,
void *a, void *b, gboolean *stop )
{
VipsImage *in = (VipsImage *) a;
VipsReducehl3 *reducehl3 = (VipsReducehl3 *) b;
const int ps = VIPS_IMAGE_SIZEOF_PEL( in );
VipsRegion *ir = (VipsRegion *) seq;
VipsRect *r = &out_region->valid;
/* Double bands for complex.
*/
const int bands = in->Bands *
(vips_band_format_iscomplex( in->BandFmt ) ? 2 : 1);
VipsRect s;
#ifdef DEBUG
printf( "vips_reducehl3_gen: generating %d x %d at %d x %d\n",
r->width, r->height, r->left, r->top );
#endif /*DEBUG*/
s.left = r->left * reducehl3->xshrink;
s.top = r->top;
s.width = r->width * reducehl3->xshrink + reducehl3->n_points;
s.height = r->height;
if( vips_region_prepare( ir, &s ) )
return( -1 );
VIPS_GATE_START( "vips_reducehl3_gen: work" );
for( int y = 0; y < r->height; y ++ ) {
VipsPel *q;
double X;
q = VIPS_REGION_ADDR( out_region, r->left, r->top + y );
X = r->left * reducehl3->xshrink;
for( int x = 0; x < r->width; x++ ) {
int ix = (int) X;
VipsPel *p = VIPS_REGION_ADDR( ir, ix, r->top + y );
const int sx = X * VIPS_TRANSFORM_SCALE * 2;
const int six = sx & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int tx = (six + 1) >> 1;
const int *cxi = reducehl3->matrixi[tx];
const double *cxf = reducehl3->matrixf[tx];
switch( in->BandFmt ) {
case VIPS_FORMAT_UCHAR:
reducehl3_unsigned_int_tab
<unsigned char, UCHAR_MAX>(
reducehl3,
q, p, bands, cxi );
break;
default:
g_assert_not_reached();
break;
}
X += reducehl3->xshrink;
q += ps;
}
}
VIPS_GATE_STOP( "vips_reducehl3_gen: work" );
return( 0 );
}
static int
vips_reducehl3_build( VipsObject *object )
{
VipsObjectClass *object_class = VIPS_OBJECT_GET_CLASS( object );
VipsResample *resample = VIPS_RESAMPLE( object );
VipsReducehl3 *reducehl3 = (VipsReducehl3 *) object;
VipsImage **t = (VipsImage **)
vips_object_local_array( object, 2 );
VipsImage *in;
if( VIPS_OBJECT_CLASS( vips_reducehl3_parent_class )->build( object ) )
return( -1 );
in = resample->in;
if( reducehl3->xshrink < 1 ) {
vips_error( object_class->nickname,
"%s", _( "reduce factors should be >= 1" ) );
return( -1 );
}
if( reducehl3->xshrink > 3 )
vips_warn( object_class->nickname,
"%s", _( "reduce factor greater than 3" ) );
if( reducehl3->xshrink == 1 )
return( vips_image_write( in, resample->out ) );
/* Build the tables of pre-computed coefficients.
*/
reducehl3->n_points = vips_reducehl3_get_points( reducehl3->kernel );
for( int x = 0; x < VIPS_TRANSFORM_SCALE + 1; x++ ) {
vips_reducehl3_make_mask( reducehl3->kernel,
(float) x / VIPS_TRANSFORM_SCALE,
reducehl3->matrixf[x] );
for( int i = 0; i < reducehl3->n_points; i++ )
reducehl3->matrixi[x][i] = reducehl3->matrixf[x][i] *
VIPS_INTERPOLATE_SCALE;
}
/* Unpack for processing.
*/
if( vips_image_decode( in, &t[0] ) )
return( -1 );
in = t[0];
/* Add new pixels around the input so we can interpolate at the edges.
*/
if( vips_embed( in, &t[1],
reducehl3->n_points / 2, 0,
in->Xsize + reducehl3->n_points - 1, in->Ysize,
"extend", VIPS_EXTEND_COPY,
NULL ) )
return( -1 );
in = t[1];
if( vips_image_pipelinev( resample->out,
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
return( -1 );
/* Size output. Note: we round the output width down!
*
* Don't change xres/yres, leave that to the application layer. For
* example, vipsthumbnail knows the true reduce factor (including the
* fractional part), we just see the integer part here.
*/
resample->out->Xsize = (in->Xsize - reducehl3->n_points + 1) /
reducehl3->xshrink;
if( resample->out->Xsize <= 0 ) {
vips_error( object_class->nickname,
"%s", _( "image has shrunk to nothing" ) );
return( -1 );
}
#ifdef DEBUG
printf( "vips_reducehl3_build: reducing %d x %d image to %d x %d\n",
in->Xsize, in->Ysize,
resample->out->Xsize, resample->out->Ysize );
#endif /*DEBUG*/
if( vips_image_generate( resample->out,
vips_start_one, vips_reducehl3_gen, vips_stop_one,
in, reducehl3 ) )
return( -1 );
return( 0 );
}
static void
vips_reducehl3_class_init( VipsReducehl3Class *reducehl3_class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( reducehl3_class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( reducehl3_class );
VipsOperationClass *operation_class =
VIPS_OPERATION_CLASS( reducehl3_class );
VIPS_DEBUG_MSG( "vips_reducehl3_class_init\n" );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "reducehl3";
vobject_class->description = _( "shrink an image horizontally" );
vobject_class->build = vips_reducehl3_build;
operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
VIPS_ARG_DOUBLE( reducehl3_class, "xshrink", 3,
_( "Xshrink" ),
_( "Horizontal shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsReducehl3, xshrink ),
1, 1000000, 1 );
VIPS_ARG_ENUM( reducehl3_class, "kernel", 3,
_( "Kernel" ),
_( "Resamling kernel" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsReducehl3, kernel ),
VIPS_TYPE_KERNEL, VIPS_KERNEL_CUBIC );
}
static void
vips_reducehl3_init( VipsReducehl3 *reducehl3 )
{
reducehl3->kernel = VIPS_KERNEL_CUBIC;
}
/**
* vips_reducehl3:
* @in: input image
* @out: output image
* @xshrink: horizontal reduce
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* @kernel: #VipsKernel to use to interpolate (default: cubic)
*
* Reduce @in horizontally by a float factor. The pixels in @out are
* interpolated with a 1D mask. This operation will not work well for
* a reduction of more than a factor of two.
*
* This is a very low-level operation: see vips_resize() for a more
* convenient way to resize images.
*
* This operation does not change xres or yres. The image resolution needs to
* be updated by the application.
*
* See also: vips_shrink(), vips_resize(), vips_affine().
*
* Returns: 0 on success, -1 on error
*/
int
vips_reducehl3( VipsImage *in, VipsImage **out, double xshrink, ... )
{
va_list ap;
int result;
va_start( ap, xshrink );
result = vips_call_split( "reducehl3", ap, in, out, xshrink );
va_end( ap );
return( result );
}

319
libvips/resample/reducevl3.cpp Normal file
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@ -0,0 +1,319 @@
/* horizontal reduce by a float factor with lanczos3
*
* 29/1/16
* - from shrinkv.c
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include <vips/debug.h>
#include <vips/internal.h>
#include "presample.h"
#include "templates.h"
typedef struct _VipsReducevl3 {
VipsResample parent_instance;
double yshrink; /* Shrink factor */
} VipsReducevl3;
typedef VipsResampleClass VipsReducevl3Class;
/* Precalculated interpolation matrices. int (used for pel
* sizes up to short), and double (for all others). We go to
* scale + 1 so we can round-to-nearest safely.
*/
const int n_points = 6;
static int vips_reducevl3_matrixi[VIPS_TRANSFORM_SCALE + 1][n_points];
static double vips_reducevl3_matrixf[VIPS_TRANSFORM_SCALE + 1][n_points];
/* We need C linkage for this.
*/
extern "C" {
G_DEFINE_TYPE( VipsReducevl3, vips_reducevl3, VIPS_TYPE_RESAMPLE );
}
template <typename T, int max_value>
static void inline
reducevl3_unsigned_int_tab( VipsPel *pout, const VipsPel *pin,
const int ne, const int lskip,
const int * restrict cy )
{
T* restrict out = (T *) pout;
const T* restrict in = (T *) pin;
const int l1 = lskip / sizeof( T );
for( int z = 0; z < ne; z++ ) {
int sum;
sum = 0;
for( int i = 0; i < n_points; i++ )
sum += cy[i] * in[i * l1];
sum = unsigned_fixed_round( sum );
sum = VIPS_CLIP( 0, sum, max_value );
out[z] = sum;
in += 1;
}
}
static int
vips_reducevl3_gen( VipsRegion *out_region, void *seq,
void *a, void *b, gboolean *stop )
{
VipsImage *in = (VipsImage *) a;
VipsReducevl3 *reducevl3 = (VipsReducevl3 *) b;
VipsRegion *ir = (VipsRegion *) seq;
VipsRect *r = &out_region->valid;
/* Double bands for complex.
*/
const int bands = in->Bands *
(vips_band_format_iscomplex( in->BandFmt ) ? 2 : 1);
int ne = r->width * bands;
VipsRect s;
#ifdef DEBUG
printf( "vips_reducevl3_gen: generating %d x %d at %d x %d\n",
r->width, r->height, r->left, r->top );
#endif /*DEBUG*/
s.left = r->left;
s.top = r->top * reducevl3->yshrink;
s.width = r->width;
s.height = r->height * reducevl3->yshrink + n_points;
if( vips_region_prepare( ir, &s ) )
return( -1 );
VIPS_GATE_START( "vips_reducevl3_gen: work" );
for( int y = 0; y < r->height; y ++ ) {
VipsPel *q = VIPS_REGION_ADDR( out_region, r->left, r->top + y );
const double Y = (r->top + y) * reducevl3->yshrink;
VipsPel *p = VIPS_REGION_ADDR( ir, r->left, (int) Y );
const int sy = Y * VIPS_TRANSFORM_SCALE * 2;
const int siy = sy & (VIPS_TRANSFORM_SCALE * 2 - 1);
const int ty = (siy + 1) >> 1;
const int *cyi = vips_reducevl3_matrixi[ty];
const double *cyf = vips_reducevl3_matrixf[ty];
const int lskip = VIPS_REGION_LSKIP( ir );
switch( in->BandFmt ) {
case VIPS_FORMAT_UCHAR:
reducevl3_unsigned_int_tab
<unsigned char, UCHAR_MAX>(
q, p, ne, lskip, cyi );
break;
default:
g_assert_not_reached();
break;
}
}
VIPS_GATE_STOP( "vips_reducevl3_gen: work" );
return( 0 );
}
static int
vips_reducevl3_build( VipsObject *object )
{
VipsObjectClass *object_class = VIPS_OBJECT_GET_CLASS( object );
VipsResample *resample = VIPS_RESAMPLE( object );
VipsReducevl3 *reducevl3 = (VipsReducevl3 *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
VipsImage *in;
if( VIPS_OBJECT_CLASS( vips_reducevl3_parent_class )->build( object ) )
return( -1 );
in = resample->in;
if( reducevl3->yshrink < 1 ) {
vips_error( object_class->nickname,
"%s", _( "reduce factors should be >= 1" ) );
return( -1 );
}
if( reducevl3->yshrink > 3 )
vips_warn( object_class->nickname,
"%s", _( "reduce factor greater than 3" ) );
if( reducevl3->yshrink == 1 )
return( vips_image_write( in, resample->out ) );
/* Unpack for processing.
*/
if( vips_image_decode( in, &t[0] ) )
return( -1 );
in = t[0];
/* Add new pixels around the input so we can interpolate at the edges.
*/
if( vips_embed( in, &t[1],
0, n_points / 2,
in->Xsize, in->Ysize + n_points - 1,
"extend", VIPS_EXTEND_COPY,
NULL ) )
return( -1 );
in = t[1];
if( vips_image_pipelinev( resample->out,
VIPS_DEMAND_STYLE_SMALLTILE, in, NULL ) )
return( -1 );
/* Size output. Note: we round the output width down!
*
* Don't change xres/yres, leave that to the application layer. For
* example, vipsthumbnail knows the true reduce factor (including the
* fractional part), we just see the integer part here.
*/
resample->out->Ysize = (in->Ysize - n_points + 1) / reducevl3->yshrink;
if( resample->out->Ysize <= 0 ) {
vips_error( object_class->nickname,
"%s", _( "image has shrunk to nothing" ) );
return( -1 );
}
#ifdef DEBUG
printf( "vips_reducevl3_build: reducing %d x %d image to %d x %d\n",
in->Xsize, in->Ysize,
resample->out->Xsize, resample->out->Ysize );
#endif /*DEBUG*/
if( vips_image_generate( resample->out,
vips_start_one, vips_reducevl3_gen, vips_stop_one,
in, reducevl3 ) )
return( -1 );
return( 0 );
}
static void
vips_reducevl3_class_init( VipsReducevl3Class *reducevl3_class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( reducevl3_class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( reducevl3_class );
VipsOperationClass *operation_class =
VIPS_OPERATION_CLASS( reducevl3_class );
VIPS_DEBUG_MSG( "vips_reducevl3_class_init\n" );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "reducevl3";
vobject_class->description = _( "shrink an image vertically" );
vobject_class->build = vips_reducevl3_build;
operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
VIPS_ARG_DOUBLE( reducevl3_class, "yshrink", 3,
_( "Xshrink" ),
_( "Vertical shrink factor" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsReducevl3, yshrink ),
1, 1000000, 1 );
/* Build the tables of pre-computed coefficients.
*/
for( int y = 0; y < VIPS_TRANSFORM_SCALE + 1; y++ ) {
calculate_coefficients_lanczos( 3,
(float) y / VIPS_TRANSFORM_SCALE,
vips_reducevl3_matrixf[y] );
for( int i = 0; i < n_points; i++ )
vips_reducevl3_matrixi[y][i] =
vips_reducevl3_matrixf[y][i] *
VIPS_INTERPOLATE_SCALE;
}
}
static void
vips_reducevl3_init( VipsReducevl3 *reducevl3 )
{
}
/**
* vips_reducevl3:
* @in: input image
* @out: output image
* @yshrink: horizontal reduce
* @...: %NULL-terminated list of optional named arguments
*
* Reduce @in vertically by a float factor. The pixels in @out are
* interpolated with a 1D cubic mask. This operation will not work well for
* a reduction of more than a factor of two.
*
* This is a very low-level operation: see vips_resize() for a more
* convenient way to resize images.
*
* This operation does not change xres or yres. The image resolution needs to
* be updated by the application.
*
* See also: vips_shrink(), vips_resize(), vips_affine().
*
* Returns: 0 on success, -1 on error
*/
int
vips_reducevl3( VipsImage *in, VipsImage **out, double yshrink, ... )
{
va_list ap;
int result;
va_start( ap, yshrink );
result = vips_call_split( "reducevl3", ap, in, out, yshrink );
va_end( ap );
return( result );
}

4
libvips/resample/resample.c
View File

@ -139,7 +139,9 @@ vips_resample_operation_init( void )
extern GType vips_shrinkv_get_type( void );
extern GType vips_reduce_get_type( void );
extern GType vips_reduceh_get_type( void );
extern GType vips_reducehl3_get_type( void );
extern GType vips_reducev_get_type( void );
extern GType vips_reducevl3_get_type( void );
extern GType vips_quadratic_get_type( void );
extern GType vips_affine_get_type( void );
extern GType vips_similarity_get_type( void );
@ -150,7 +152,9 @@ vips_resample_operation_init( void )
vips_shrinkh_get_type();
vips_shrinkv_get_type();
vips_reduceh_get_type();
vips_reducehl3_get_type();
vips_reducev_get_type();
vips_reducevl3_get_type();
vips_reduce_get_type();
vips_quadratic_get_type();
vips_affine_get_type();

24
libvips/resample/templates.h
View File

@ -312,18 +312,30 @@ calculate_coefficients_catmull( const double x, double c[4] )
}
/* Given an offset in [0,1] (we can have x == 1 when building tables),
* calculate c0 .. c6, the lanczos3 coefficients. This is called
* calculate c0 .. c(a * 2 - 1), the lanczos coefficients. This is called
* from the interpolator as well as from the table builder.
*/
static void inline
calculate_coefficients_lanczos3( const double x, double c[7] )
calculate_coefficients_lanczos( int a, const double x, double *c )
{
int i;
for( i = 0; i < 7; i++ ) {
double xp = (i - 3) + x;
for( i = 0; i < a * 2; i++ ) {
double xp = (i - a) + (1 - x);
c[i] = 3.0 * sin( VIPS_PI * xp ) * sin( VIPS_PI * xp / 3.0 ) /
(VIPS_PI * VIPS_PI * xp * xp);
double l;
if( xp == 0.0 )
l = 1.0;
else if( xp < -a )
l = 0.0;
else if( xp > a )
l = 0.0;
else
l = (double) a * sin( VIPS_PI * xp ) *
sin( VIPS_PI * xp / (double) a ) /
(VIPS_PI * VIPS_PI * xp * xp);
c[i] = l;
}
}