416 lines
11 KiB
C
416 lines
11 KiB
C
/* crop an image down to a specified size by removing boring parts
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*
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* Copyright: 2017, J. Cupitt
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*
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* Adapted from sharp's smartcrop feature, with kind permission.
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*
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* 1/3/17
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* - first version, from sharp
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* 14/3/17
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* - revised attention smartcrop
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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 VIPS_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 <string.h>
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#include <stdlib.h>
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#include <vips/vips.h>
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#include <vips/debug.h>
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#include "pconversion.h"
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#include "bandary.h"
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typedef struct _VipsSmartcrop {
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VipsConversion parent_instance;
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VipsImage *in;
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int width;
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int height;
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VipsInteresting interesting;
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} VipsSmartcrop;
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typedef VipsConversionClass VipsSmartcropClass;
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G_DEFINE_TYPE( VipsSmartcrop, vips_smartcrop, VIPS_TYPE_CONVERSION );
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static int
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vips_smartcrop_score( VipsSmartcrop *smartcrop, VipsImage *in,
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int left, int top, int width, int height, double *score )
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{
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VipsImage **t = (VipsImage **)
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vips_object_local_array( VIPS_OBJECT( smartcrop ), 2 );
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if( vips_extract_area( in, &t[0], left, top, width, height, NULL ) ||
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vips_hist_find( t[0], &t[1], NULL ) ||
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vips_hist_entropy( t[1], score, NULL ) )
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return( -1 );
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return( 0 );
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}
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/* Entropy-style smartcrop. Repeatedly discard low interest areas. This should
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* be faster for very large images.
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*/
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static int
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vips_smartcrop_entropy( VipsSmartcrop *smartcrop,
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VipsImage *in, int *left, int *top )
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{
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int max_slice_size;
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int width;
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int height;
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*left = 0;
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*top = 0;
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width = in->Xsize;
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height = in->Ysize;
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/* How much do we trim by each iteration? Aim for 8 steps in the axis
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* that needs trimming most.
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*/
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max_slice_size = VIPS_MAX(
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ceil( (width - smartcrop->width) / 8.0 ),
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ceil( (height - smartcrop->height) / 8.0 ) );
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/* Repeatedly take a slice off width and height until we
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* reach the target.
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*/
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while( width > smartcrop->width ||
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height > smartcrop->height ) {
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const int slice_width =
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VIPS_MIN( width - smartcrop->width, max_slice_size );
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const int slice_height =
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VIPS_MIN( height - smartcrop->height, max_slice_size );
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if( slice_width > 0 ) {
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double left_score;
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double right_score;
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if( vips_smartcrop_score( smartcrop, in,
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*left, *top, slice_width, height, &left_score ) )
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return( -1 );
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if( vips_smartcrop_score( smartcrop, in,
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*left + width - slice_width, *top,
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slice_width, height, &right_score ) )
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return( -1 );
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width -= slice_width;
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if( left_score < right_score )
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*left += slice_width;
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}
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if( slice_height > 0 ) {
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double top_score;
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double bottom_score;
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if( vips_smartcrop_score( smartcrop, in,
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*left, *top, width, slice_height, &top_score ) )
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return( -1 );
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if( vips_smartcrop_score( smartcrop, in,
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*left, *top + height - slice_height,
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width, slice_height, &bottom_score ) )
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return( -1 );
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height -= slice_height;
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if( top_score < bottom_score )
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*top += slice_height;
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}
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}
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return( 0 );
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}
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static int
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vips_smartcrop_attention( VipsSmartcrop *smartcrop,
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VipsImage *in, int *left, int *top )
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{
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/* ab ranges for skin colours. Trained with http://humanae.tumblr.com/
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*/
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static double ab_low[2] = { 3.0, 4.0 };
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static double ab_high[2] = { 22.0, 31.0 };
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VipsImage **t = (VipsImage **)
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vips_object_local_array( VIPS_OBJECT( smartcrop ), 24 );
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double hshrink;
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double vshrink;
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double sigma;
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double max;
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int x_pos;
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int y_pos;
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if( !(t[21] = vips_image_new_matrixv( 3, 3,
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-1.0, 0.0, 1.0, -2.0, 0.0, 2.0, -1.0, 0.0, 1.0 )) )
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return( -1 );
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if( vips_rot( t[21], &t[22], VIPS_ANGLE_D90, NULL ) )
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return( -1 );
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/* Convert to LAB and just use the first three bands.
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*/
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if( vips_colourspace( in, &t[0], VIPS_INTERPRETATION_LAB, NULL ) ||
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vips_extract_band( t[0], &t[1], 0, "n", 3, NULL ) )
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return( -1 );
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/* Sobel edge-detect on L.
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*/
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if( vips_extract_band( t[1], &t[2], 0, NULL ) ||
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vips_conv( t[2], &t[3], t[21],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ||
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vips_conv( t[2], &t[4], t[22],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ||
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vips_abs( t[3], &t[5], NULL ) ||
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vips_abs( t[4], &t[6], NULL ) ||
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vips_add( t[5], t[6], &t[7], NULL ) )
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return( -1 );
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/* Look for skin colours, plus L > 15.
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*/
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if( vips_extract_band( t[1], &t[8], 1, "n", 2, NULL ) ||
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vips_moreeq_const( t[8], &t[9], ab_low, 2, NULL ) ||
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vips_lesseq_const( t[8], &t[10], ab_high, 2, NULL ) ||
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vips_andimage( t[9], t[10], &t[11], NULL ) ||
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vips_bandand( t[11], &t[12], NULL ) ||
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vips_moreeq_const1( t[2], &t[18], 15.0, NULL ) ||
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vips_andimage( t[12], t[18], &t[19], NULL ) )
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return( -1 );
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/* Look for saturated areas.
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*/
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if( vips_colourspace( t[1], &t[13],
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VIPS_INTERPRETATION_LCH, NULL ) ||
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vips_extract_band( t[13], &t[14], 1, NULL ) ||
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vips_more_const1( t[14], &t[15], 60.0, NULL ) )
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return( -1 );
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/* Sum, shrink, blur and find maxpos.
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*
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* The size we shrink to gives the precision with which we can place
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* the crop, the amount of blur is related to the size of the crop
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* area: how large an area we want to consider for the scoring
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* function.
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*/
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hshrink = in->Xsize / 32.0;
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vshrink = in->Ysize / 32.0;
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sigma = sqrt( pow( smartcrop->width / hshrink, 2 ) +
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pow( smartcrop->height / vshrink, 2 ) ) / 6;
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if( vips_add( t[7], t[19], &t[16], NULL ) ||
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vips_add( t[16], t[15], &t[17], NULL ) ||
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vips_shrink( t[17], &t[20], hshrink, vshrink, NULL ) ||
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vips_gaussblur( t[20], &t[23], sigma, NULL ) ||
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vips_max( t[23], &max, "x", &x_pos, "y", &y_pos, NULL ) )
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return( -1 );
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/* Centre the crop over the max.
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*/
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*left = VIPS_CLIP( 0,
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hshrink * x_pos - smartcrop->width / 2,
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in->Xsize - smartcrop->width );
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*top = VIPS_CLIP( 0,
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vshrink * y_pos - smartcrop->height / 2,
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in->Ysize - smartcrop->height );
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return( 0 );
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}
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static int
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vips_smartcrop_build( VipsObject *object )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
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VipsConversion *conversion = VIPS_CONVERSION( object );
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VipsSmartcrop *smartcrop = (VipsSmartcrop *) object;
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 2 );
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VipsImage *in;
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int left;
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int top;
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if( VIPS_OBJECT_CLASS( vips_smartcrop_parent_class )->
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build( object ) )
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return( -1 );
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if( smartcrop->width > smartcrop->in->Xsize ||
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smartcrop->height > smartcrop->in->Ysize ||
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smartcrop->width <= 0 || smartcrop->height <= 0 ) {
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vips_error( class->nickname, "%s", _( "bad extract area" ) );
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return( -1 );
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}
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in = smartcrop->in;
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/* If there's an alpha, we have to premultiply before searching for
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* content. There could be stuff in transparent areas which we don't
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* want to consider.
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*/
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if( vips_image_hasalpha( in ) ) {
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if( vips_premultiply( in, &t[0], NULL ) )
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return( -1 );
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in = t[0];
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}
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switch( smartcrop->interesting ) {
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case VIPS_INTERESTING_NONE:
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left = 0;
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top = 0;
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break;
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case VIPS_INTERESTING_CENTRE:
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left = (smartcrop->in->Xsize - smartcrop->width) / 2;
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top = (smartcrop->in->Ysize - smartcrop->height) / 2;
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break;
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case VIPS_INTERESTING_ENTROPY:
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if( vips_smartcrop_entropy( smartcrop, in, &left, &top ) )
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return( -1 );
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break;
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case VIPS_INTERESTING_ATTENTION:
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if( vips_smartcrop_attention( smartcrop, in, &left, &top ) )
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return( -1 );
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break;
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default:
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g_assert_not_reached();
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/* Stop a compiler warning.
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*/
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left = 0;
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top = 0;
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break;
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}
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if( vips_extract_area( smartcrop->in, &t[1],
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left, top, smartcrop->width, smartcrop->height, NULL ) ||
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vips_image_write( t[1], conversion->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_smartcrop_class_init( VipsSmartcropClass *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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VIPS_DEBUG_MSG( "vips_smartcrop_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 = "smartcrop";
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vobject_class->description = _( "extract an area from an image" );
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vobject_class->build = vips_smartcrop_build;
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VIPS_ARG_IMAGE( class, "input", 0,
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_( "Input" ),
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_( "Input image" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsSmartcrop, in ) );
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VIPS_ARG_INT( class, "width", 4,
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_( "Width" ),
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_( "Width of extract area" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsSmartcrop, width ),
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1, VIPS_MAX_COORD, 1 );
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VIPS_ARG_INT( class, "height", 5,
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_( "Height" ),
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_( "Height of extract area" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsSmartcrop, height ),
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1, VIPS_MAX_COORD, 1 );
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VIPS_ARG_ENUM( class, "interesting", 6,
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_( "Interesting" ),
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_( "How to measure interestingness" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsSmartcrop, interesting ),
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VIPS_TYPE_INTERESTING, VIPS_INTERESTING_ATTENTION );
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}
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static void
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vips_smartcrop_init( VipsSmartcrop *smartcrop )
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{
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smartcrop->interesting = VIPS_INTERESTING_ATTENTION;
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}
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/**
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* vips_smartcrop:
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* @in: input image
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* @out: output image
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* @width: width of area to extract
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* @height: height of area to extract
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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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* * @interesting: #VipsInteresting to use to find interesting areas (default: #VIPS_INTERESTING_ATTENTION)
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*
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* Crop an image down to a specified width and height by removing boring parts.
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*
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* Use @interesting to pick the method vips uses to decide which bits of the
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* image should be kept.
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*
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* You can test xoffset / yoffset on @out to find the location of the crop
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* within the input image.
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*
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* See also: vips_extract_area().
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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_smartcrop( VipsImage *in, VipsImage **out, int width, int height, ... )
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{
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va_list ap;
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int result;
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va_start( ap, height );
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result = vips_call_split( "smartcrop", ap, in, out, width, height );
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va_end( ap );
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return( result );
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}
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