start adding canny
just adding edge thinning see https://en.wikipedia.org/wiki/Canny_edge_detector
This commit is contained in:
John Cupitt
parent
ce1f236c4d
commit
a93e8dd079
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@ -1,6 +1,7 @@
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noinst_LTLIBRARIES = libconvolution.la
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libconvolution_la_SOURCES = \
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canny.c \
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convolution.c \
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pconvolution.h \
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correlation.c \
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@ -0,0 +1,342 @@
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/* Canny edge detector
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*
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* 2/2/18
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* - from vips_canny()
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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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typedef struct _VipsCanny {
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VipsOperation parent_instance;
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VipsImage *in;
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VipsImage *out;
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gdouble sigma;
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/* Need an image vector for start_many.
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*/
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VipsImage *args[3];
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} VipsCanny;
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typedef VipsOperationClass VipsCannyClass;
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G_DEFINE_TYPE( VipsCanny, vips_canny, VIPS_TYPE_OPERATION );
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static int
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vips_canny_polar_generate( VipsRegion *or,
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void *vseq, void *a, void *b, gboolean *stop )
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{
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VipsRegion **in = (VipsRegion **) vseq;
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VipsRect *r = &or->valid;
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VipsImage *Gx = in[0]->im;
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int x, y, band;
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if( vips_reorder_prepare_many( or->im, in, r ) )
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return( -1 );
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for( y = 0; y < r->height; y++ ) {
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VipsPel *p1 = (VipsPel * restrict)
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VIPS_REGION_ADDR( in[0], r->left, r->top + y );
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VipsPel *p2 = (VipsPel * restrict)
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VIPS_REGION_ADDR( in[1], r->left, r->top + y );
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VipsPel *q = (VipsPel * restrict)
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VIPS_REGION_ADDR( or, r->left, r->top + y );
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for( x = 0; x < r->width; x++ ) {
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for( band = 0; band < Gx->Bands; band++ ) {
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int x = p1[band] - 128;
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int y = p2[band] - 128;
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int a = VIPS_DEG( atan2( x, y ) );
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q[0] = sqrt( x * x + y * y );
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q[1] = ((a + 360 + 22) / 45) & 0x3;
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q += 2;
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}
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p1 += Gx->Bands;
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p2 += Gx->Bands;
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}
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}
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return( 0 );
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}
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/* Calculate G/theta from Gx/Gy -- rather like rect -> polar, except that we
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* constrain theta to 0/45/90/135, which we code as 0/1/2/3, and we don't care
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* about the sign of G.
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*
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* Theta values:
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*
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* 3 | 0 | 1
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* --+---+--
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* 2 | x | 2
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* --+---+--
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* 1 | 0 | 3
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*/
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static int
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vips_canny_polar( VipsImage **args, VipsImage **out )
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{
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*out = vips_image_new();
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if( vips_image_pipeline_array( *out,
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VIPS_DEMAND_STYLE_THINSTRIP, args ) )
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return( -1 );
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(*out)->Bands *= 2;
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if( vips_image_generate( *out,
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vips_start_many, vips_canny_polar_generate, vips_stop_many,
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args, NULL ) )
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return( -1 );
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return( 0 );
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}
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static int
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vips_canny_nonmax_generate( VipsRegion *or,
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void *vseq, void *a, void *b, gboolean *stop )
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{
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VipsRegion *in = (VipsRegion *) vseq;
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VipsRect *r = &or->valid;
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VipsImage *im = in->im;
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VipsRect rect;
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int x, y, band;
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int lsk;
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int
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rect = *r;
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rect.width += 2;
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rect.height += 2;
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if( vips_region_prepare( in, &rect ) )
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return( -1 );
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lsk = VIPS_REGION_LSKIP( in );
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for( y = 0; y < r->height; y++ ) {
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VipsPel *p = (VipsPel * restrict)
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VIPS_REGION_ADDR( in, r->left, r->top + y );
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VipsPel *q = (VipsPel * restrict)
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VIPS_REGION_ADDR( or, r->left, r->top + y );
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for( x = 0; x < r->width; x++ ) {
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for( band = 0; band < im->Bands; band++ ) {
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int G = p[0];
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int theta = p[1];
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int v1, v2;
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if( theta == 0 ) {
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v1 = p[
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switch( theta ) {
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case 0:
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q[band] = x;
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p += 2;
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}
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q += im->Bands;
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}
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}
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return( 0 );
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}
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/* Remove non-maximal edges. At each point, compare the G to the G in either
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* direction and 0 it if it's not the largest.
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*/
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static int
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vips_canny_nonmax( VipsImage *in, VipsImage **out )
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{
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*out = vips_image_new();
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if( vips_image_pipeline_arrayv( *out,
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VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
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return( -1 );
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(*out)->Bands /= 2;
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(*out)->Xsize -= 2;
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(*out)->Ysize -= 2;
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if( vips_image_generate( *out,
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vips_start_one, vips_canny_nonmax_generate, vips_stop_one,
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in, NULL ) )
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return( -1 );
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return( 0 );
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}
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static int
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vips_canny_build( VipsObject *object )
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{
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VipsCanny *canny = (VipsCanny *) object;
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VipsImage **t = (VipsImage **) vips_object_local_array( object, 20 );
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VipsImage *in;
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VipsImage *Gx;
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VipsImage *Gy;
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if( VIPS_OBJECT_CLASS( vips_canny_parent_class )->build( object ) )
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return( -1 );
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in = canny->in;
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if( vips_gaussblur( in, &t[0], canny->sigma, NULL ) )
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return( -1 );
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in = t[0];
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/* Separated Sobel gives Gx / Gy. Aim for vector path.
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*/
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t[1] = vips_image_new_matrixv( 1, 3, 1.0, 2.0, 1.0 );
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t[2] = vips_image_new_matrixv( 3, 1, 1.0, 0.0, -1.0 );
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vips_image_set_double( t[2], "offset", 128.0 );
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if( vips_conv( in, &t[3], t[1],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ||
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vips_conv( t[3], &t[4], t[2],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) )
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return( -1 );
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Gx = t[4];
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t[5] = vips_image_new_matrixv( 3, 1, 1.0, 2.0, 1.0 );
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t[6] = vips_image_new_matrixv( 1, 3, 1.0, 0.0, -1.0 );
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vips_image_set_double( t[6], "offset", 128.0 );
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if( vips_conv( in, &t[7], t[5],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ||
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vips_conv( t[7], &t[8], t[6],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) )
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return( -1 );
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Gy = t[8];
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/* Form (G, theta), with theta coded.
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*/
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canny->args[0] = Gx;
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canny->args[1] = Gy;
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canny->args[2] = NULL;
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if( vips_canny_polar( canny->args, &t[9] ) )
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return( -1 );
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in = t[9];
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g_object_set( object, "out", vips_image_new(), NULL );
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if( vips_image_write( in, canny->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_canny_class_init( VipsCannyClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *object_class = (VipsObjectClass *) class;
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VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
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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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object_class->nickname = "canny";
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object_class->description = _( "gaussian blur" );
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object_class->build = vips_canny_build;
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operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
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VIPS_ARG_IMAGE( class, "in", 1,
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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( VipsCanny, in ) );
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VIPS_ARG_IMAGE( class, "out", 2,
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_( "Output" ),
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_( "Output image" ),
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VIPS_ARGUMENT_REQUIRED_OUTPUT,
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G_STRUCT_OFFSET( VipsCanny, out ) );
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VIPS_ARG_DOUBLE( class, "sigma", 10,
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_( "Sigma" ),
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_( "Sigma of Gaussian" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsCanny, sigma ),
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0.01, 1000, 1.4 );
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}
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static void
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vips_canny_init( VipsCanny *canny )
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{
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canny->sigma = 1.4;
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}
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/**
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* vips_canny: (method)
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* @in: input image
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* @out: (out): output image
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* @sigma: how large a mask to use
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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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* * @sigma: %gdouble, sigma for gaussian blur
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*
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* See also: vips_gaussblur().
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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_canny( VipsImage *in, VipsImage **out, ... )
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{
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va_list ap;
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int result;
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va_start( ap, out );
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result = vips_call_split( "canny", ap, in, out );
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va_end( ap );
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return( result );
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}
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@ -168,6 +168,7 @@ vips_convolution_operation_init( void )
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extern int vips_spcor_get_type( void );
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extern int vips_sharpen_get_type( void );
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extern int vips_gaussblur_get_type( void );
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extern int vips_canny_get_type( void );
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vips_conv_get_type();
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vips_conva_get_type();
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@ -180,4 +181,5 @@ vips_convolution_operation_init( void )
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vips_spcor_get_type();
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vips_sharpen_get_type();
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vips_gaussblur_get_type();
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vips_canny_get_type();
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}
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@ -70,6 +70,9 @@ int vips_spcor( VipsImage *in, VipsImage *ref, VipsImage **out, ... )
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int vips_fastcor( VipsImage *in, VipsImage *ref, VipsImage **out, ... )
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__attribute__((sentinel));
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int vips_canny( VipsImage *in, VipsImage **out, ... )
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__attribute__((sentinel));
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#ifdef __cplusplus
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}
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#endif /*__cplusplus*/
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