376 lines
10 KiB
C
376 lines
10 KiB
C
/* resize an image ... up and down resampling.
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*
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* 13/8/14
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* - from affine.c
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* 18/11/14
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* - add the fancier algorithm from vipsthumbnail
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* 11/11/15
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* - smarter cache sizing
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* 29/2/16
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* - shrink more affine less, now we have better anti-alias settings
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* 10/3/16
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* - revise again, using new vips_reduce() code
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* 1/5/16
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* - allow >1 on one axis, <1 on the other
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* - expose @kernel setting
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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/*
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#define DEBUG_VERBOSE
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#define DEBUG
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <limits.h>
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#include <vips/vips.h>
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#include <vips/debug.h>
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#include <vips/internal.h>
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#include <vips/transform.h>
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#include "presample.h"
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typedef struct _VipsResize {
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VipsResample parent_instance;
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double scale;
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double vscale;
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VipsKernel kernel;
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/* Deprecated.
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*/
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VipsInterpolate *interpolate;
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double idx;
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double idy;
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} VipsResize;
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typedef VipsResampleClass VipsResizeClass;
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G_DEFINE_TYPE( VipsResize, vips_resize, VIPS_TYPE_RESAMPLE );
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static int
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vips_resize_build( VipsObject *object )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
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VipsResample *resample = VIPS_RESAMPLE( object );
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VipsResize *resize = (VipsResize *) object;
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 7 );
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VipsImage *in;
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int target_width;
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int target_height;
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int int_hshrink;
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int int_vshrink;
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double hresidual;
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double vresidual;
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if( VIPS_OBJECT_CLASS( vips_resize_parent_class )->build( object ) )
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return( -1 );
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in = resample->in;
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/* The image size we are aiming for.
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*/
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target_width = in->Xsize * resize->scale;
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if( vips_object_argument_isset( object, "vscale" ) )
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target_height = in->Ysize * resize->vscale;
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else
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target_height = in->Ysize * resize->scale;
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/* If the factor is > 1.0, we need to zoom rather than shrink.
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* Just set the int part to 1 in this case.
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*/
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/* We want the int part of the shrink to leave a bit to do with
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* blur/reduce/sharpen, or we'll see strange changes in aliasing on int
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* shrink boundaries as we resize.
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*/
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if( resize->scale > 1.0 )
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int_hshrink = 1;
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else
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int_hshrink = VIPS_FLOOR( 1.0 / (resize->scale * 2) );
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if( vips_object_argument_isset( object, "vscale" ) ) {
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if( resize->vscale > 1.0 )
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int_vshrink = 1;
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else
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int_vshrink = VIPS_FLOOR( 1.0 / (resize->vscale * 2) );
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}
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else
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int_vshrink = int_hshrink;
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if( int_vshrink > 1 ) {
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vips_info( class->nickname, "shrinkv by %d", int_vshrink );
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if( vips_shrinkv( in, &t[0], int_vshrink, NULL ) )
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return( -1 );
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in = t[0];
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}
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if( int_hshrink > 1 ) {
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vips_info( class->nickname, "shrinkh by %d", int_hshrink );
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if( vips_shrinkh( in, &t[1], int_hshrink, NULL ) )
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return( -1 );
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in = t[1];
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}
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/* Do we need a further size adjustment? It's the difference
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* between our target size and the size we have after vips_shrink().
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*
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* This can break the aspect ratio slightly :/ but hopefully no one
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* will notice.
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*/
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hresidual = (double) target_width / in->Xsize;
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vresidual = (double) target_height / in->Ysize;
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/* We will get overcomputation on vips_shrink() from the vips_reduce()
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* coming later, so read into a cache where tiles are scanlines, and
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* make sure we keep enough scanlines.
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*
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* We use a threaded tilecache to avoid a deadlock: suppose thread1,
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* evaluating the top block of the output, is delayed, and thread2,
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* evaluating the second block, gets here first (this can happen on
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* a heavily-loaded system).
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*
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* With an unthreaded tilecache, thread2 will get
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* the cache lock and start evaling the second block of the shrink.
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* When it reaches the png reader it will stall until the first block
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* has been used ... but it never will, since thread1 will block on
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* this cache lock.
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*
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* Cache sizing: we double-buffer writes, so threads can be up to one
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* line of tiles behind. For example, one thread could be allocated
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* tile (0,0) and then stall, the whole write system won't stall until
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* it tries to allocate tile (0, 2).
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*
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* We reduce down after this, which can be a scale of up to @residual,
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* perhaps 0.5 or down as low as 0.3. So the number of scanlines we
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* need to keep for the worst case is 2 * @tile_height / @residual,
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* plus a little extra.
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*/
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if( int_vshrink > 1 ) {
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int tile_width;
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int tile_height;
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int n_lines;
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int need_lines;
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vips_get_tile_size( in,
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&tile_width, &tile_height, &n_lines );
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need_lines = 1.2 * n_lines / vresidual;
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if( vips_tilecache( in, &t[6],
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"tile_width", in->Xsize,
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"tile_height", 10,
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"max_tiles", 1 + need_lines / 10,
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"access", VIPS_ACCESS_SEQUENTIAL,
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"threaded", TRUE,
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NULL ) )
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return( -1 );
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in = t[6];
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}
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/* Any residual downsizing.
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*/
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if( vresidual < 1.0 ) {
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vips_info( class->nickname, "residual reducev by %g",
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vresidual );
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if( vips_reducev( in, &t[2], 1.0 / vresidual,
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"kernel", resize->kernel,
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NULL ) )
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return( -1 );
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in = t[2];
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}
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if( hresidual < 1.0 ) {
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vips_info( class->nickname, "residual reduceh by %g",
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hresidual );
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if( vips_reduceh( in, &t[3], 1.0 / hresidual,
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"kernel", resize->kernel,
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NULL ) )
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return( -1 );
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in = t[3];
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}
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/* Any upsizing.
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*/
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if( hresidual > 1.0 ) {
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vips_info( class->nickname, "residual scaleh %g",
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hresidual );
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if( vips_affine( in, &t[4], hresidual, 0.0, 0.0, 1.0,
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"interpolate", vips_interpolate_nearest_static(),
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NULL ) )
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return( -1 );
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in = t[4];
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}
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if( vresidual > 1.0 ) {
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vips_info( class->nickname, "residual scalev %g", vresidual );
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if( vips_affine( in, &t[5], 1.0, 0.0, 0.0, vresidual,
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"interpolate", vips_interpolate_nearest_static(),
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NULL ) )
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return( -1 );
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in = t[5];
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}
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if( vips_image_write( in, resample->out ) )
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return( -1 );
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return( 0 );
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}
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static void
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vips_resize_class_init( VipsResizeClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
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VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
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VIPS_DEBUG_MSG( "vips_resize_class_init\n" );
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gobject_class->set_property = vips_object_set_property;
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gobject_class->get_property = vips_object_get_property;
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vobject_class->nickname = "resize";
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vobject_class->description = _( "resize an image" );
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vobject_class->build = vips_resize_build;
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operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
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VIPS_ARG_DOUBLE( class, "scale", 113,
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_( "Scale factor" ),
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_( "Scale image by this factor" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsResize, scale ),
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0, 10000000, 0 );
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VIPS_ARG_DOUBLE( class, "vscale", 113,
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_( "Vertical scale factor" ),
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_( "Vertical scale image by this factor" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsResize, vscale ),
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0, 10000000, 0 );
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VIPS_ARG_ENUM( class, "kernel", 3,
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_( "Kernel" ),
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_( "Resampling kernel" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsResize, kernel ),
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VIPS_TYPE_KERNEL, VIPS_KERNEL_LANCZOS3 );
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/* We used to let people set the input offset so you could pick centre
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* or corner interpolation, but it's not clear this was useful.
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*/
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VIPS_ARG_DOUBLE( class, "idx", 115,
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_( "Input offset" ),
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_( "Horizontal input displacement" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
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G_STRUCT_OFFSET( VipsResize, idx ),
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-10000000, 10000000, 0 );
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VIPS_ARG_DOUBLE( class, "idy", 116,
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_( "Input offset" ),
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_( "Vertical input displacement" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
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G_STRUCT_OFFSET( VipsResize, idy ),
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-10000000, 10000000, 0 );
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/* We used to let people set the interpolator, but it's not clear this
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* was useful. Anyway, vips_reduce() no longer has an interpolator
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* param.
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*/
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VIPS_ARG_INTERPOLATE( class, "interpolate", 2,
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_( "Interpolate" ),
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_( "Interpolate pixels with this" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
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G_STRUCT_OFFSET( VipsResize, interpolate ) );
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}
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static void
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vips_resize_init( VipsResize *resize )
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{
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resize->kernel = VIPS_KERNEL_LANCZOS3;
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}
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/**
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* vips_resize:
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* @in: input image
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* @out: output image
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* @scale: scale factor
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* @...: %NULL-terminated list of optional named arguments
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*
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* Optional arguments:
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*
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* @vscale: vertical scale factor
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* @kernel: #VipsKernel to reduce with
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*
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* Resize an image. When upsizing (@scale > 1), the image is simply block
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* upsized. When downsizing, the
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* image is block-shrunk with vips_shrink(),
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* then the image is shrunk again to the
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* target size with vips_reduce(). The operation will leave at least the final
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* x2 to be done with vips_reduce().
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*
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* vips_resize() normally maintains the image apect ratio. If you set
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* @vscale, that factor is used for the vertical scale and @scale for the
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* horizontal.
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*
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* vips_resize() normally uses #VIPS_KERNEL_LANCZOS3 for thre final shrink, you
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* can change this with @kernel.
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*
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* This operation does not change xres or yres. The image resolution needs to
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* be updated by the application.
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*
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* See also: vips_shrink(), vips_reduce().
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*
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* Returns: 0 on success, -1 on error
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*/
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int
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vips_resize( VipsImage *in, VipsImage **out,
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double scale, ... )
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{
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va_list ap;
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int result;
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va_start( ap, scale );
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result = vips_call_split( "resize", ap, in, out, scale );
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va_end( ap );
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return( result );
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}
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