first paste of aconv
This commit is contained in:
John Cupitt
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542
libvips/convolution/im_aconv.c
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542
libvips/convolution/im_aconv.c
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@ -0,0 +1,542 @@
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/* im_aconv ... approximate convolution
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*
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* This operation does an approximate, seperable convolution.
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*
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* Author: John Cupitt & Nicolas Robidoux
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* Written on: 31/5/11
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* Modified on:
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* 31/5/11
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* - from im_conv()
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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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/* Show sample pixels as they are transformed.
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#define DEBUG_PIXELS
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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 <limits.h>
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#include <vips/vips.h>
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#include <vips/vector.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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/* Maximum number of lines we can break the mask into.
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*/
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#define MAX_LINES (1000)
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/* Euclid's algorithm. Use this to common up mults.
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*/
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static int
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gcd( int a, int b )
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{
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if( b == 0 )
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return( abs( a ) );
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else
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return( gcd( b, a % b ) );
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}
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/* A set of lines.
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*/
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typedef struct _Lines {
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/* Copy of our arguments.
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*/
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IMAGE *in;
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IMAGE *out;
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DOUBLEMASK *mask;
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int n_lines;
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int area;
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int rounding;
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/* Start is the left-most pixel in the line, end is one beyond the
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* right-most pixel.
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*/
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int n_lines;
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int start[MAX_LINES];
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int end[MAX_LINES];
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int factor[MAX_LINES];
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} Lines;
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static void
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line_start( Lines *lines, int x, int factor )
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{
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lines->start[lines->n_lines] = x;
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lines->factor[lines->n_lines] = factor;
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}
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static int
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line_end( Lines *lines, int x )
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{
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lines->end[lines->n_lines] = x;
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lines->n_lines += 1;
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if( lines->n_lines >= MAX_LINES ) {
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vips_error( "im_aconv", "%s", _( "mask too complex" ) );
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return( -1 );
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}
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return( 0 );
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}
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/* Break a mask into lines.
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*/
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static Lines *
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lines_new( IMAGE *in, IMAGE *out, DOUBLEMASK *mask, int n_lines )
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{
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const int width = mask->xsize * mask->ysize;
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Lines *lines;
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double max;
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double min;
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double depth;
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int lines_above;
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int lines_below;
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int z, n, x;
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/* Check parameters.
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*/
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if( vips_image_pio_input( in ) ||
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vips_image_pio_output( out ) ||
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vips_check_uncoded( "im_aconv", in ) ||
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vips_check_dmask_1d( "im_aconv", mask ) )
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return( NULL );
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if( !(lines = VIPS_NEW( out, Lines )) )
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return( NULL );
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lines->in = in;
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lines->out = out;
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if( !(lines->mask = (DOUBLEMASK *) im_local( out,
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(im_construct_fn) im_dup_dmask,
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(im_callback_fn) im_free_dmask, mask, mask->filename, NULL )) )
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return( NULL );
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lines->n_lines = n_lines;
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lines->n_lines = 0;
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VIPS_DEBUG_MSG( "lines_new: breaking into %d lines ...\n", n_lines );
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/* Find mask range. We must always include the zero axis in the mask.
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*/
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max = 0;
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min = 0;
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for( x = 0; x < width; x++ ) {
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if( mask->coeff[x] > max )
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max = mask->coeff[x];
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if( mask->coeff[x] < min )
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min = mask->coeff[x];
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}
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/* The zero axis must fall on a layer boundary. Estimate the
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* depth, find n-lines-above-zero, get exact depth, then calculate a
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* fixed n-lines which includes any negative parts.
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*/
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depth = (max - min) / n_lines;
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lines_above = ceil( max / depth );
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depth = max / lines_above;
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lines_below = floor( min / depth );
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n_lines = lines_above - lines_below;
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VIPS_DEBUG_MSH( "depth = %g, n_lines = %d\n", depth, n_lines );
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/* For each layer, generate a set of lines which are inside the
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* perimeter. Work down from the top.
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*/
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for( z = 0; z < n_lines; z++ ) {
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double y = max - (1 + z) * depth;
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/* Odd, but we must avoid rounding errors that make us miss 0
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* in the line above.
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*/
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int y_positive = z < lines_above;
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int inside;
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/* Start outside the perimeter.
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*/
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inside = 0;
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for( x = 0; x < width; x++ ) {
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/* The vertical line from mask[z] to 0 is inside. Is
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* our current square (x, y) part of that line?
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*/
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if( (y_positive && mask->coeff[x] > y + depth / 2) ||
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(!y_positive && mask->coeff[x] < y + depth / 2) ) {
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/* (x, y) is inside.
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*/
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if( !inside ) {
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line_start( lines,
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x, y_positive ? 1 : -1 );
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inside = 1;
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}
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}
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else {
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/* (x, y) is outside.
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*/
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if( inside ) {
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if( line_end( lines, x ) )
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return( NULL );
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inside = 0;
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}
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}
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}
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if( inside &&
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line_end( lines, mask->xsize - 1 ) )
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return( NULL );
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}
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/* Can we common up any lines? Search for lines with identical
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* start/end.
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*/
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for( z = 0; z < lines->n_lines; z++ ) {
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for( n = z + 1; n < lines->n_lines; n++ ) {
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if( lines->start[z] == lines->start[n] &&
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lines->end[z] == lines->end[n] ) {
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lines->factor[z] += lines->factor[n];
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/* n can be deleted. Do this in a separate
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* pass below.
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*/
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lines->factor[n] = 0;
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}
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}
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}
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/* Now we can remove all factor 0 lines.
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*/
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for( z = 0; z < lines->n_lines; z++ ) {
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if( lines->factor[z] == 0 ) {
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for( x = z; x < lines->n_lines; x++ ) {
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lines->start[x] = lines->start[x + 1];
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lines->end[x] = lines->end[x + 1];
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lines->factor[x] = lines->factor[x + 1];
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}
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lines->n_lines -= 1;
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}
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}
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/* Find the area of the lines.
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*/
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lines->area = 0;
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for( z = 0; z < lines->n_lines; z++ )
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lines->area += lines->factor[z] *
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(lines->end[z] - lines->start[z]);
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/* Strength reduction: if all lines are divisible by n, we can move
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* that n out into the ->area factor. The aim is to produce as many
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* factor 1 lines as we can and to reduce the chance of overflow.
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*/
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x = lines->factor[0];
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for( z = 1; z < lines->n_lines; z++ )
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x = gcd( x, lines->factor[z] );
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for( z = 0; z < lines->n_lines; z++ )
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lines->factor[z] /= x;
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lines->area *= x;
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lines->rounding = (lines->area + 1) / 2;
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/* ASCII-art layer drawing.
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*/
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printf( "lines:\n" );
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for( z = 0; z < lines->n_lines; z++ ) {
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printf( "%3d - %2d x ", z, lines->factor[z] );
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for( x = 0; x < 55; x++ ) {
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int rx = x * width / 55;
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if( rx >= lines->start[z] && rx < lines->end[z] )
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printf( "#" );
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else
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printf( " " );
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}
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printf( " %3d .. %3d\n", lines->start[z], lines->end[z] );
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}
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printf( "area = %d\n", lines->area );
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printf( "rounding = %d\n", lines->rounding );
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return( lines );
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}
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/* Our sequence value.
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*/
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typedef struct {
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Lines *lines;
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REGION *ir; /* Input region */
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int *start; /* Offsets for start and stop */
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int *end;
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int last_bpl; /* Avoid recalcing offsets, if we can */
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PEL **startp; /* Pixel pointers */
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PEL **endp;
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} LinesSequence;
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/* Free a sequence value.
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*/
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static int
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lines_stop( void *vseq, void *a, void *b )
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{
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LinesSequence *seq = (LinesSequence *) vseq;
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IM_FREEF( im_region_free, seq->ir );
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return( 0 );
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}
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/* Convolution start function.
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*/
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static void *
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lines_start( IMAGE *out, void *a, void *b )
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{
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IMAGE *in = (IMAGE *) a;
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Lines *lines = (Lines *) b;
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DOUBLEMASK *mask = lines->mask;
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const int n_mask = mask->xsize * mask->ysize;
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LinesSequence *seq;
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if( !(seq = IM_NEW( out, LinesSequence )) )
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return( NULL );
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/* Init!
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*/
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seq->lines = lines;
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seq->ir = im_region_create( in );
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seq->start = IM_ARRAY( out, lines->n_lines, int );
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seq->end = IM_ARRAY( out, lines->n_lines, int );
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seq->startp = IM_ARRAY( out, lines->n_lines, PEL * );
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seq->endp = IM_ARRAY( out, lines->n_lines, PEL * );
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seq->last_bpl = -1;
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if( !seq->ir ||
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!seq->start || !seq->end ||
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!seq->startp || !seq->endp ) {
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lines_stop( seq, in, lines );
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return( NULL );
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}
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return( seq );
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}
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static int
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lines_generate( REGION *or, void *seq, void *a, void *b )
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{
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REGION *ir = (REGION *) seq;
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IMAGE *in = (IMAGE *) a;
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Lines *lines = (Lines *) b;
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const int n_lines = lines->n_lines;
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DOUBLEMASK *mask = lines->mask;
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Rect *r = &or->valid;
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Rect s;
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int x, y, z;
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/* Prepare the section of the input image we need. A little larger
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* than the section of the output image we are producing.
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*/
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s = *r;
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s.width += mask->xsize - 1;
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s.height += mask->ysize - 1;
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if( im_prepare( ir, &s ) )
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return( -1 );
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/* Fill offset array. Only do this if the bpl has changed since the
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* previous im_prepare().
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*/
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if( seq->last_bpl != IM_REGION_LSKIP( ir ) ) {
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seq->last_bpl = IM_REGION_LSKIP( ir );
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for( z = 0; z < n_lines; z++ ) {
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x = mask->xsize == 1 ? 1 : lines->start[z];
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y = mask->ysize == 1 ? 1 : lines->start[z];
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seq->start[z] =
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IM_REGION_ADDR( ir, x + r->left, y + r->top ) -
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IM_REGION_ADDR( ir, r->left, r->top );
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x = mask->xsize == 1 ? 1 : lines->end[z];
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y = mask->ysize == 1 ? 1 : lines->end[z];
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seq->end[z] =
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IM_REGION_ADDR( ir, x + r->left, y + r->top ) -
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IM_REGION_ADDR( ir, r->left, r->top );
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}
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}
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for( y = 0; y < r->height; y++ ) {
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PEL *q = (PEL *) IM_REGION_ADDR( or, r->left, r->top + y );
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PEL *p = (PEL *) IM_REGION_ADDR( ir, le, y );
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/* Init pts for this line of PELs.
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*/
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for( z = 0; z < n_lines; z++ ) {
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seq->startp[z] = p + seq->start[z];
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seq->endp[z] = p + seq->end[z];
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}
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switch( in->BandFmt ) {
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case IM_BANDFMT_UCHAR:
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{
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int sum;
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int line_sum[1000];
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/* Fill the lines ready to scan.
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*/
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sum = 0;
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for( z = 0; z < lines->n_lines; z++ ) {
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line_sum[z] = 0;
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for( x = seq->startp[z]; x < lines->end[z]; x++ )
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line_sum[z] += p[x];
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sum += lines->factor[z] * line_sum[z];
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}
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q[0] = CLIPUC( (sum + lines->rounding) / lines->area );
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for( x = 1; x < len; x++ ) {
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sum = 0;
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for( z = 0; z < lines->n_lines; z++ ) {
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line_sum[z] += p[lines->end[z]];
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line_sum[z] -= p[lines->start[z]];
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sum += lines->factor[z] * line_sum[z];
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}
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p += 1;
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q[x] = CLIPUC( (sum + lines->rounding) / lines->area );
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}
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}
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break;
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default:
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g_assert( 0 );
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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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aconv_raw( IMAGE *in, IMAGE *out, DOUBLEMASK *mask, int n_layers )
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{
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Lines *lines;
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#ifdef DEBUG
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printf( "im_conv_raw: starting with matrix:\n" );
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im_print_imask( mask );
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#endif /*DEBUG*/
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if( !(lines = lines_new( in, out, mask, n_layers )) )
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return( -1 );
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/* Prepare output. Consider a 7x7 mask and a 7x7 image --- the output
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* would be 1x1.
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*/
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if( im_cp_desc( out, in ) )
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return( -1 );
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out->Xsize -= mask->xsize - 1;
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out->Ysize -= mask->ysize - 1;
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if( out->Xsize <= 0 || out->Ysize <= 0 ) {
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im_error( "im_conv", "%s", _( "image too small for mask" ) );
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return( -1 );
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}
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/* Set demand hints. FATSTRIP is good for us, as THINSTRIP will cause
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* too many recalculations on overlaps.
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*/
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if( im_demand_hint( out, IM_FATSTRIP, in, NULL ) ||
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im_generate( out,
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lines_start, lines_generate, lines_stop, in, lines ) )
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return( -1 );
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out->Xoffset = -mask->xsize / 2;
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out->Yoffset = -mask->ysize / 2;
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return( 0 );
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}
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/**
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* im_aconv:
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* @in: input image
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* @out: output image
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* @mask: convolution mask
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* @n_layers: number of layers for approximation
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*
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* Perform a separable convolution of @in with @mask using approximate
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* convolution.
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*
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* The mask must be 1xn or nx1 elements.
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* The output image
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* always has the same #VipsBandFmt as the input image.
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*
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* The image is convolved twice: once with @mask and then again with @mask
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* rotated by 90 degrees.
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*
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* Larger values for @n_layers give more accurate
|
||||
* results, but are slower. As @n_layers approaches the mask radius, the
|
||||
* accuracy will become close to exact convolution and the speed will drop to
|
||||
* match. For many large masks, such as Gaussian, @n_layers can be only 10% of
|
||||
* this value and accuracy will still be good.
|
||||
*
|
||||
* See also: im_convsep_f(), im_create_dmaskv().
|
||||
*
|
||||
* Returns: 0 on success, -1 on error
|
||||
*/
|
||||
int
|
||||
im_aconv( IMAGE *in, IMAGE *out, DOUBLEMASK *mask, int n_layers )
|
||||
{
|
||||
IMAGE *t[2];
|
||||
const int n_mask = mask->xsize * mask->ysize;
|
||||
DOUBLEMASK *rmask;
|
||||
|
||||
if( vips_image_new_array( out, t, 2 ) ||
|
||||
!(rmask = (DOUBLEMASK *) im_local( out,
|
||||
(im_construct_fn) im_dup_dmask,
|
||||
(im_callback_fn) im_free_dmask, mask, mask->filename, NULL )) )
|
||||
return( -1 );
|
||||
|
||||
rmask->xsize = mask->ysize;
|
||||
rmask->ysize = mask->xsize;
|
||||
|
||||
if( im_embed( in, t[0], 1, n_mask / 2, n_mask / 2,
|
||||
in->Xsize + n_mask - 1, in->Ysize + n_mask - 1 ) ||
|
||||
aconv_raw( t[0], t[1], mask, n_layers ) ||
|
||||
aconv_raw( t[1], out, rmask, n_layers ) )
|
||||
return( -1 );
|
||||
|
||||
out->Xoffset = 0;
|
||||
out->Yoffset = 0;
|
||||
|
||||
return( 0 );
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user