340 lines
8.3 KiB
C
340 lines
8.3 KiB
C
/* subsample
|
|
*
|
|
* 3/7/95 JC
|
|
* - adapted from im_shrink()
|
|
* 3/8/02 JC
|
|
* - fall back to im_copy() for x/y factors == 1
|
|
* 21/4/08
|
|
* - don't fall back to pixel-wise shrinks for smalltile, it kills
|
|
* performance, just bring VIPS_MAX_WIDTH down instead
|
|
* 1/2/10
|
|
* - gtkdoc
|
|
* 1/6/13
|
|
* - redo as a class
|
|
* 2/11/13
|
|
* - add @point to force point sample mode
|
|
* 22/1/16
|
|
* - remove SEQUENTIAL hint, it confuses vips_sequential()
|
|
*/
|
|
|
|
/*
|
|
|
|
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
|
|
|
|
*/
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include <config.h>
|
|
#endif /*HAVE_CONFIG_H*/
|
|
#include <vips/intl.h>
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
#include <vips/vips.h>
|
|
|
|
#include "pconversion.h"
|
|
|
|
typedef struct _VipsSubsample {
|
|
VipsConversion parent_instance;
|
|
|
|
VipsImage *in;
|
|
int xfac;
|
|
int yfac;
|
|
gboolean point;
|
|
|
|
} VipsSubsample;
|
|
|
|
typedef VipsConversionClass VipsSubsampleClass;
|
|
|
|
G_DEFINE_TYPE( VipsSubsample, vips_subsample, VIPS_TYPE_CONVERSION );
|
|
|
|
/* Maximum width of input we ask for.
|
|
*/
|
|
#define VIPS_MAX_WIDTH (100)
|
|
|
|
/* Subsample a VipsRegion. We fetch in VIPS_MAX_WIDTH pixel-wide strips,
|
|
* left-to-right across the input.
|
|
*/
|
|
static int
|
|
vips_subsample_line_gen( VipsRegion *or,
|
|
void *seq, void *a, void *b, gboolean *stop )
|
|
{
|
|
VipsRegion *ir = (VipsRegion *) seq;
|
|
VipsSubsample *subsample = (VipsSubsample *) b;
|
|
VipsImage *in = (VipsImage *) a;
|
|
VipsRect *r = &or->valid;
|
|
int le = r->left;
|
|
int ri = VIPS_RECT_RIGHT( r );
|
|
int to = r->top;
|
|
int bo = VIPS_RECT_BOTTOM( r );
|
|
int ps = VIPS_IMAGE_SIZEOF_PEL( in );
|
|
int owidth = VIPS_MAX_WIDTH / subsample->xfac;
|
|
|
|
VipsRect s;
|
|
int x, y;
|
|
int z, k;
|
|
|
|
/* Loop down the region.
|
|
*/
|
|
for( y = to; y < bo; y++ ) {
|
|
VipsPel *q = VIPS_REGION_ADDR( or, le, y );
|
|
VipsPel *p;
|
|
|
|
/* Loop across the region, in owidth sized pieces.
|
|
*/
|
|
for( x = le; x < ri; x += owidth ) {
|
|
/* How many pixels do we make this time?
|
|
*/
|
|
int ow = VIPS_MIN( owidth, ri - x );
|
|
|
|
/* Ask for this many from input ... can save a
|
|
* little here!
|
|
*/
|
|
int iw = ow * subsample->xfac - (subsample->xfac - 1);
|
|
|
|
/* Ask for input.
|
|
*/
|
|
s.left = x * subsample->xfac;
|
|
s.top = y * subsample->yfac;
|
|
s.width = iw;
|
|
s.height = 1;
|
|
if( vips_region_prepare( ir, &s ) )
|
|
return( -1 );
|
|
|
|
/* Append new pels to output.
|
|
*/
|
|
p = VIPS_REGION_ADDR( ir, s.left, s.top );
|
|
for( z = 0; z < ow; z++ ) {
|
|
for( k = 0; k < ps; k++ )
|
|
q[k] = p[k];
|
|
|
|
q += ps;
|
|
p += ps * subsample->xfac;
|
|
}
|
|
}
|
|
}
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
/* Fetch one pixel at a time ... good for very large shrinks.
|
|
*/
|
|
static int
|
|
vips_subsample_point_gen( VipsRegion *or,
|
|
void *seq, void *a, void *b, gboolean *stop )
|
|
{
|
|
VipsRegion *ir = (VipsRegion *) seq;
|
|
VipsSubsample *subsample = (VipsSubsample *) b;
|
|
VipsImage *in = (VipsImage *) a;
|
|
VipsRect *r = &or->valid;
|
|
int le = r->left;
|
|
int ri = VIPS_RECT_RIGHT( r );
|
|
int to = r->top;
|
|
int bo = VIPS_RECT_BOTTOM(r);
|
|
int ps = VIPS_IMAGE_SIZEOF_PEL( in );
|
|
|
|
VipsRect s;
|
|
int x, y;
|
|
int k;
|
|
|
|
/* Loop down the region.
|
|
*/
|
|
for( y = to; y < bo; y++ ) {
|
|
VipsPel *q = VIPS_REGION_ADDR( or, le, y );
|
|
VipsPel *p;
|
|
|
|
/* Loop across the region, in owidth sized pieces.
|
|
*/
|
|
for( x = le; x < ri; x++ ) {
|
|
/* Ask for input.
|
|
*/
|
|
s.left = x * subsample->xfac;
|
|
s.top = y * subsample->yfac;
|
|
s.width = 1;
|
|
s.height = 1;
|
|
if( vips_region_prepare( ir, &s ) )
|
|
return( -1 );
|
|
|
|
/* Append new pels to output.
|
|
*/
|
|
p = VIPS_REGION_ADDR( ir, s.left, s.top );
|
|
for( k = 0; k < ps; k++ )
|
|
q[k] = p[k];
|
|
q += ps;
|
|
}
|
|
}
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
static int
|
|
vips_subsample_build( VipsObject *object )
|
|
{
|
|
VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
|
|
VipsConversion *conversion = VIPS_CONVERSION( object );
|
|
VipsSubsample *subsample = (VipsSubsample *) object;
|
|
|
|
VipsGenerateFn subsample_fn;
|
|
|
|
if( VIPS_OBJECT_CLASS( vips_subsample_parent_class )->build( object ) )
|
|
return( -1 );
|
|
|
|
g_assert( subsample->xfac > 0 );
|
|
g_assert( subsample->yfac > 0 );
|
|
|
|
if( subsample->xfac == 1 &&
|
|
subsample->yfac == 1 )
|
|
return( vips_image_write( subsample->in, conversion->out ) );
|
|
if( vips_image_pio_input( subsample->in ) ||
|
|
vips_check_coding_known( class->nickname, subsample->in ) )
|
|
return( -1 );
|
|
|
|
/* Set demand hints. We want THINSTRIP, as we will be demanding a
|
|
* large area of input for each output line.
|
|
*/
|
|
if( vips_image_pipelinev( conversion->out,
|
|
VIPS_DEMAND_STYLE_THINSTRIP, subsample->in, NULL ) )
|
|
return( -1 );
|
|
|
|
/* Prepare output. Note: we round the output width down!
|
|
*/
|
|
conversion->out->Xsize = subsample->in->Xsize / subsample->xfac;
|
|
conversion->out->Ysize = subsample->in->Ysize / subsample->yfac;
|
|
conversion->out->Xres = subsample->in->Xres / subsample->xfac;
|
|
conversion->out->Yres = subsample->in->Yres / subsample->yfac;
|
|
if( conversion->out->Xsize <= 0 ||
|
|
conversion->out->Ysize <= 0 ) {
|
|
vips_error( class->nickname,
|
|
"%s", _( "image has shrunk to nothing" ) );
|
|
return( -1 );
|
|
}
|
|
|
|
/* Generate! If this is a very large shrink, then it's probably faster
|
|
* to do it a pixel at a time.
|
|
*/
|
|
if( subsample->point ||
|
|
subsample->xfac > 10 )
|
|
subsample_fn = vips_subsample_point_gen;
|
|
else
|
|
subsample_fn = vips_subsample_line_gen;
|
|
|
|
if( vips_image_generate( conversion->out,
|
|
vips_start_one, subsample_fn, vips_stop_one,
|
|
subsample->in, subsample ) )
|
|
return( -1 );
|
|
|
|
return( 0 );
|
|
}
|
|
|
|
static void
|
|
vips_subsample_class_init( VipsSubsampleClass *class )
|
|
{
|
|
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
|
|
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
|
|
|
|
gobject_class->set_property = vips_object_set_property;
|
|
gobject_class->get_property = vips_object_get_property;
|
|
|
|
vobject_class->nickname = "subsample";
|
|
vobject_class->description = _( "subsample an image" );
|
|
vobject_class->build = vips_subsample_build;
|
|
|
|
/* We don't work well as sequential: we can easily skip the first few
|
|
* scanlines, and that confuses vips_sequential().
|
|
*/
|
|
|
|
VIPS_ARG_IMAGE( class, "input", 1,
|
|
_( "Input" ),
|
|
_( "Input image" ),
|
|
VIPS_ARGUMENT_REQUIRED_INPUT,
|
|
G_STRUCT_OFFSET( VipsSubsample, in ) );
|
|
|
|
VIPS_ARG_INT( class, "xfac", 3,
|
|
_( "Xfac" ),
|
|
_( "Horizontal subsample factor" ),
|
|
VIPS_ARGUMENT_REQUIRED_INPUT,
|
|
G_STRUCT_OFFSET( VipsSubsample, xfac ),
|
|
1, VIPS_MAX_COORD, 1 );
|
|
|
|
VIPS_ARG_INT( class, "yfac", 4,
|
|
_( "Yfac" ),
|
|
_( "Vertical subsample factor" ),
|
|
VIPS_ARGUMENT_REQUIRED_INPUT,
|
|
G_STRUCT_OFFSET( VipsSubsample, yfac ),
|
|
1, VIPS_MAX_COORD, 1 );
|
|
|
|
VIPS_ARG_BOOL( class, "point", 5,
|
|
_( "Point" ),
|
|
_( "Point sample" ),
|
|
VIPS_ARGUMENT_OPTIONAL_INPUT,
|
|
G_STRUCT_OFFSET( VipsSubsample, point ),
|
|
FALSE );
|
|
|
|
}
|
|
|
|
static void
|
|
vips_subsample_init( VipsSubsample *subsample )
|
|
{
|
|
}
|
|
|
|
/**
|
|
* vips_subsample: (method)
|
|
* @in: input image
|
|
* @out: (out): output image
|
|
* @xfac: horizontal shrink factor
|
|
* @yfac: vertical shrink factor
|
|
* @...: %NULL-terminated list of optional named arguments
|
|
*
|
|
* Optional arguments:
|
|
*
|
|
* * @point: turn on point sample mode
|
|
*
|
|
* Subsample an image by an integer fraction. This is fast, nearest-neighbour
|
|
* shrink.
|
|
*
|
|
* For small horizontal shrinks, this operation will fetch lines of pixels
|
|
* from @in and then subsample that line. For large shrinks it will fetch
|
|
* single pixels.
|
|
*
|
|
* If @point is set, @in will always be sampled in points. This can be faster
|
|
* if the previous operations in the pipeline are very slow.
|
|
*
|
|
* See also: vips_affine(), vips_shrink(), vips_zoom().
|
|
*
|
|
* Returns: 0 on success, -1 on error.
|
|
*/
|
|
int
|
|
vips_subsample( VipsImage *in, VipsImage **out, int xfac, int yfac, ... )
|
|
{
|
|
va_list ap;
|
|
int result;
|
|
|
|
va_start( ap, yfac );
|
|
result = vips_call_split( "subsample", ap, in, out, xfac, yfac );
|
|
va_end( ap );
|
|
|
|
return( result );
|
|
}
|