372 lines
9.3 KiB
C
372 lines
9.3 KiB
C
/* horizontal shrink by an integer factor
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*
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* 30/10/15
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* - from shrink.c
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* 22/1/16
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* - reorganise loops, 30% faster, vectorisable
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* 15/8/16
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* - rename xshrink -> hshrink for greater consistency
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* 6/8/19
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* - use a double sum buffer for int32 types
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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
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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 <math.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 "presample.h"
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typedef struct _VipsShrinkh {
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VipsResample parent_instance;
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int hshrink; /* Shrink factor */
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} VipsShrinkh;
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typedef VipsResampleClass VipsShrinkhClass;
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G_DEFINE_TYPE( VipsShrinkh, vips_shrinkh, VIPS_TYPE_RESAMPLE );
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#define INNER( BANDS ) \
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sum += p[x1]; \
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x1 += BANDS;
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/* Integer shrink.
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*/
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#define ISHRINK( ACC_TYPE, TYPE, BANDS ) { \
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TYPE * restrict p = (TYPE *) in; \
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TYPE * restrict q = (TYPE *) out; \
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\
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for( x = 0; x < width; x++ ) { \
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for( b = 0; b < BANDS; b++ ) { \
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ACC_TYPE sum; \
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\
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sum = 0; \
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x1 = b; \
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VIPS_UNROLL( shrink->hshrink, INNER( BANDS ) ); \
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q[b] = (sum + shrink->hshrink / 2) / \
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shrink->hshrink; \
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} \
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p += ne; \
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q += BANDS; \
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} \
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}
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/* Float shrink.
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*/
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#define FSHRINK( TYPE ) { \
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TYPE * restrict p = (TYPE *) in; \
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TYPE * restrict q = (TYPE *) out; \
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\
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for( x = 0; x < width; x++ ) { \
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for( b = 0; b < bands; b++ ) { \
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double sum; \
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\
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sum = 0.0; \
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x1 = b; \
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VIPS_UNROLL( shrink->hshrink, INNER( bands ) ); \
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q[b] = sum / shrink->hshrink; \
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} \
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p += ne; \
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q += bands; \
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} \
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}
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/* Generate an area of @or. @ir is large enough.
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*/
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static void
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vips_shrinkh_gen2( VipsShrinkh *shrink, VipsRegion *or, VipsRegion *ir,
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int left, int top, int width )
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{
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VipsResample *resample = VIPS_RESAMPLE( shrink );
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const int bands = resample->in->Bands *
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(vips_band_format_iscomplex( resample->in->BandFmt ) ?
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2 : 1);
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const int ne = shrink->hshrink * bands;
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VipsPel *out = VIPS_REGION_ADDR( or, left, top );
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VipsPel *in = VIPS_REGION_ADDR( ir, left * shrink->hshrink, top );
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int x;
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int x1, b;
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switch( resample->in->BandFmt ) {
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case VIPS_FORMAT_UCHAR:
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/* Generate a special path for 1, 3 and 4 band uchar data. The
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* compiler will be able to vectorise these.
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*
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* Vectorisation doesn't help much for 16, 32-bit or float
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* data, don't bother with them.
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*/
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switch( bands ) {
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case 1:
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ISHRINK( int, unsigned char, 1 ); break;
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case 3:
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ISHRINK( int, unsigned char, 3 ); break;
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case 4:
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ISHRINK( int, unsigned char, 4 ); break;
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default:
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ISHRINK( int, unsigned char, bands ); break;
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}
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break;
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case VIPS_FORMAT_CHAR:
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ISHRINK( int, char, bands ); break;
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case VIPS_FORMAT_USHORT:
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ISHRINK( int, unsigned short, bands ); break;
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case VIPS_FORMAT_SHORT:
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ISHRINK( int, short, bands ); break;
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case VIPS_FORMAT_UINT:
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ISHRINK( double, unsigned int, bands ); break;
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case VIPS_FORMAT_INT:
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ISHRINK( double, int, bands ); break;
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case VIPS_FORMAT_FLOAT:
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FSHRINK( float ); break;
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case VIPS_FORMAT_DOUBLE:
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FSHRINK( double ); break;
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case VIPS_FORMAT_COMPLEX:
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FSHRINK( float ); break;
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case VIPS_FORMAT_DPCOMPLEX:
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FSHRINK( double ); break;
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default:
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g_assert_not_reached();
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}
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}
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static int
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vips_shrinkh_gen( VipsRegion *or, void *seq,
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void *a, void *b, gboolean *stop )
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{
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VipsShrinkh *shrink = (VipsShrinkh *) b;
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VipsRegion *ir = (VipsRegion *) seq;
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VipsRect *r = &or->valid;
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int y;
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/* How do we chunk up the image? We don't want to prepare the whole of
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* the input region corresponding to *r since it could be huge.
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*
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* Request input a line at a time.
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*
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* We don't chunk horizontally. We want "vips shrink x.jpg b.jpg 100
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* 100" to run sequentially. If we chunk horizontally, we will fetch
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* 100x100 lines from the top of the image, then 100x100 100 lines
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* down, etc. for each thread, then when they've finished, fetch
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* 100x100, 100 pixels across from the top of the image. This will
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* break sequentiality.
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*/
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#ifdef DEBUG
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printf( "vips_shrinkh_gen: generating %d x %d at %d x %d\n",
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r->width, r->height, r->left, r->top );
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#endif /*DEBUG*/
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for( y = 0; y < r->height; y ++ ) {
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VipsRect s;
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s.left = r->left * shrink->hshrink;
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s.top = r->top + y;
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s.width = r->width * shrink->hshrink;
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s.height = 1;
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#ifdef DEBUG
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printf( "shrinkh_gen: requesting line %d\n", s.top );
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#endif /*DEBUG*/
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if( vips_region_prepare( ir, &s ) )
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return( -1 );
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VIPS_GATE_START( "vips_shrinkh_gen: work" );
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vips_shrinkh_gen2( shrink, or, ir,
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r->left, r->top + y, r->width );
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VIPS_GATE_STOP( "vips_shrinkh_gen: work" );
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}
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VIPS_COUNT_PIXELS( or, "vips_shrinkh_gen" );
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return( 0 );
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}
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static int
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vips_shrinkh_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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VipsShrinkh *shrink = (VipsShrinkh *) object;
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VipsImage **t = (VipsImage **)
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vips_object_local_array( object, 2 );
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VipsImage *in;
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if( VIPS_OBJECT_CLASS( vips_shrinkh_parent_class )->build( object ) )
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return( -1 );
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in = resample->in;
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if( shrink->hshrink < 1 ) {
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vips_error( class->nickname,
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"%s", _( "shrink factors should be >= 1" ) );
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return( -1 );
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}
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if( shrink->hshrink == 1 )
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return( vips_image_write( in, resample->out ) );
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/* We need new pixels at the right so that we don't have small chunks
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* to average down the right edge.
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*/
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if( vips_embed( in, &t[1],
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0, 0,
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in->Xsize + shrink->hshrink, in->Ysize,
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"extend", VIPS_EXTEND_COPY,
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NULL ) )
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return( -1 );
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in = t[1];
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if( vips_image_pipelinev( resample->out,
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VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
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return( -1 );
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/* Size output. We need to always round to nearest, so round(), not
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* rint().
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*
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* Don't change xres/yres, leave that to the application layer. For
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* example, vipsthumbnail knows the true shrink factor (including the
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* fractional part), we just see the integer part here.
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*/
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resample->out->Xsize = VIPS_ROUND_UINT(
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(double) resample->in->Xsize / shrink->hshrink );
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if( resample->out->Xsize <= 0 ) {
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vips_error( class->nickname,
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"%s", _( "image has shrunk to nothing" ) );
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return( -1 );
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}
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#ifdef DEBUG
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printf( "vips_shrinkh_build: shrinking %d x %d image to %d x %d\n",
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in->Xsize, in->Ysize,
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resample->out->Xsize, resample->out->Ysize );
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#endif /*DEBUG*/
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if( vips_image_generate( resample->out,
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vips_start_one, vips_shrinkh_gen, vips_stop_one,
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in, shrink ) )
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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_shrinkh_class_init( VipsShrinkhClass *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_shrinkh_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 = "shrinkh";
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vobject_class->description = _( "shrink an image horizontally" );
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vobject_class->build = vips_shrinkh_build;
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operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
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VIPS_ARG_INT( class, "hshrink", 8,
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_( "Hshrink" ),
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_( "Horizontal shrink factor" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsShrinkh, hshrink ),
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1, 1000000, 1 );
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/* The old name .. now use h and v everywhere.
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*/
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VIPS_ARG_INT( class, "xshrink", 8,
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_( "Xshrink" ),
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_( "Horizontal shrink factor" ),
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VIPS_ARGUMENT_REQUIRED_INPUT | VIPS_ARGUMENT_DEPRECATED,
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G_STRUCT_OFFSET( VipsShrinkh, hshrink ),
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1, 1000000, 1 );
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}
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static void
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vips_shrinkh_init( VipsShrinkh *shrink )
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{
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}
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/**
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* vips_shrinkh: (method)
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* @in: input image
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* @out: (out): output image
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* @hshrink: horizontal shrink
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* @...: %NULL-terminated list of optional named arguments
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*
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* Shrink @in horizontally by an integer factor. Each pixel in the output is
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* the average of the corresponding line of @hshrink pixels in the input.
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*
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* This is a very low-level operation: see vips_resize() for a more
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* convenient way to resize images.
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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_shrinkv(), vips_shrink(), vips_resize(), vips_affine().
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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_shrinkh( VipsImage *in, VipsImage **out, int hshrink, ... )
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{
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va_list ap;
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int result;
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va_start( ap, hshrink );
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result = vips_call_split( "shrinkh", ap, in, out, hshrink );
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va_end( ap );
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return( result );
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}
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