split thresh stuff out of canny
This commit is contained in:
John Cupitt
parent
7328f47333
commit
3fe9b7abc5
@ -1,7 +1,5 @@
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/* Canny edge detector
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/* Canny edge detector
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*
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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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/*
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/*
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@ -32,11 +30,7 @@
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*/
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*/
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/* TODO
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/* TODO
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* - add autothreshold with otsu's method
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* - add sobel option?
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* - support other image types
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* - support other image types
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*
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* - leave blob analysis to a separate pass
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*/
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*/
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/*
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/*
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@ -62,8 +56,6 @@ typedef struct _VipsCanny {
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double sigma;
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double sigma;
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gboolean interpolate;
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gboolean interpolate;
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double low;
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double high;
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/* Need an image vector for start_many.
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/* Need an image vector for start_many.
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*/
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*/
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@ -460,68 +452,11 @@ vips_canny_nonmaxi( VipsImage *in, VipsImage **out )
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return( 0 );
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return( 0 );
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}
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}
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static int
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vips_canny_thresh_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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VipsCanny *canny = (VipsCanny *) b;
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VipsRect *r = &or->valid;
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int sz = r->width * in->im->Bands;
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VipsPel low = canny->low;
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VipsPel high = canny->high;
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int x, y;
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if( vips_region_prepare( in, r ) )
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return( -1 );
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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 < sz; x++ ) {
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int v;
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v = p[x];
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if( v <= low )
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v = 0;
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else if( v <= high )
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v = 128;
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else
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v = 255;
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q[x] = v;
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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_canny_thresh( VipsCanny *canny, VipsImage *in, VipsImage **out )
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{
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*out = vips_image_new();
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if( vips_image_pipelinev( *out,
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VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
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return( -1 );
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if( vips_image_generate( *out,
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vips_start_one, vips_canny_thresh_generate, vips_stop_one,
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in, canny ) )
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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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static int
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vips_canny_build( VipsObject *object )
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vips_canny_build( VipsObject *object )
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{
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{
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VipsCanny *canny = (VipsCanny *) object;
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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 **t = (VipsImage **) vips_object_local_array( object, 5 );
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VipsImage *in;
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VipsImage *in;
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VipsImage *Gx;
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VipsImage *Gx;
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@ -532,6 +467,12 @@ vips_canny_build( VipsObject *object )
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in = canny->in;
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in = canny->in;
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/* We are 8-bit only.
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*/
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if( vips_cast_uchar( in, &t[4], NULL ) )
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return( -1 );
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in = t[4];
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if( vips_gaussblur( in, &t[0], canny->sigma, NULL ) )
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if( vips_gaussblur( in, &t[0], canny->sigma, NULL ) )
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return( -1 );
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return( -1 );
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in = t[0];
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in = t[0];
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@ -544,31 +485,25 @@ vips_canny_build( VipsObject *object )
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canny->args[0] = Gx;
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canny->args[0] = Gx;
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canny->args[1] = Gy;
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canny->args[1] = Gy;
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canny->args[2] = NULL;
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canny->args[2] = NULL;
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if( vips_canny_polar( canny->args, &t[9] ) )
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if( vips_canny_polar( canny->args, &t[1] ) )
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return( -1 );
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return( -1 );
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in = t[9];
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in = t[1];
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/* Expand by two pixels all around, then thin.
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/* Expand by two pixels all around, then thin.
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*/
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*/
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if( vips_embed( in, &t[10], 1, 1, in->Xsize + 2, in->Ysize + 2,
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if( vips_embed( in, &t[2], 1, 1, in->Xsize + 2, in->Ysize + 2,
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"extend", VIPS_EXTEND_COPY,
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"extend", VIPS_EXTEND_COPY,
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NULL ) )
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NULL ) )
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return( -1 );
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return( -1 );
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if( canny->interpolate ) {
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if( canny->interpolate ) {
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if( vips_canny_nonmaxi( t[10], &t[11] ) )
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if( vips_canny_nonmaxi( t[2], &t[3] ) )
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return( -1 );
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return( -1 );
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}
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}
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else {
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else {
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if( vips_canny_nonmax( t[10], &t[11] ) )
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if( vips_canny_nonmax( t[2], &t[3] ) )
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return( -1 );
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return( -1 );
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}
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}
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in = t[11];
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in = t[3];
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/* Double threshold.
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*/
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if( vips_canny_thresh( canny, in, &t[12] ) )
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return( -1 );
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in = t[12];
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g_object_set( object, "out", vips_image_new(), NULL );
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g_object_set( object, "out", vips_image_new(), NULL );
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@ -613,20 +548,6 @@ vips_canny_class_init( VipsCannyClass *class )
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G_STRUCT_OFFSET( VipsCanny, sigma ),
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G_STRUCT_OFFSET( VipsCanny, sigma ),
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0.01, 1000, 1.4 );
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0.01, 1000, 1.4 );
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VIPS_ARG_DOUBLE( class, "low", 11,
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_( "Low" ),
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_( "Low threshold" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsCanny, low ),
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-INFINITY, INFINITY, 3.0 );
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VIPS_ARG_DOUBLE( class, "high", 12,
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_( "High" ),
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_( "High threshold" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsCanny, high ),
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-INFINITY, INFINITY, 7.0 );
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VIPS_ARG_BOOL( class, "interpolate", 13,
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VIPS_ARG_BOOL( class, "interpolate", 13,
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_( "Interpolate" ),
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_( "Interpolate" ),
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_( "Interpolate gradient angles" ),
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_( "Interpolate gradient angles" ),
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@ -640,8 +561,6 @@ static void
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vips_canny_init( VipsCanny *canny )
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vips_canny_init( VipsCanny *canny )
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{
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{
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canny->sigma = 1.4;
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canny->sigma = 1.4;
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canny->low = 3.0;
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canny->high = 7.0;
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}
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}
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/**
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/**
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@ -654,8 +573,22 @@ vips_canny_init( VipsCanny *canny )
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* Optional arguments:
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* Optional arguments:
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*
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*
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* * @sigma: %gdouble, sigma for gaussian blur
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* * @sigma: %gdouble, sigma for gaussian blur
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* * @interpolate: %gboolean, interpolate gradient on corners
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*
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*
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* See also: vips_gaussblur().
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* Find edges by Canny's method: The maximum of the derivative of the gradient
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* in the direction of the gradient. This operation will only work well on
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* 8-bit luminance images.
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*
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* Use @sigma to control the scale over which gradient is measured. 1.4 is
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* usually a good value.
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*
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* Set @interpolate to smoothly interpolate the gradient around corners. This
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* slows down edge detection, but can improve the result.
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*
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* You will probably need to process the output further to eliminate weak
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* edges.
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*
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* See also: vips_sobel().
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*
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*
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* Returns: 0 on success, -1 on error.
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* Returns: 0 on success, -1 on error.
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*/
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*/
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672
libvips/convolution/strong_edge.c
Normal file
672
libvips/convolution/strong_edge.c
Normal file
@ -0,0 +1,672 @@
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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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/* TODO
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* - add autothreshold with otsu's method
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* - support other image types
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*
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* - leave blob analysis to a separate pass
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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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double sigma;
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gboolean interpolate;
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double low;
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double high;
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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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/* Simple 2x2 -1/+1 difference.
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*/
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static int
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vips_canny_gradient_simple( VipsImage *in, VipsImage **Gx, VipsImage **Gy )
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{
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VipsImage *scope;
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VipsImage **t;
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scope = vips_image_new();
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t = (VipsImage **) vips_object_local_array( (VipsObject *) scope, 20 );
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t[1] = vips_image_new_matrixv( 2, 2,
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-1.0, 1.0,
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-1.0, 1.0 );
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vips_image_set_double( t[1], "offset", 128.0 );
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if( vips_conv( in, Gx, t[1],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ) {
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g_object_unref( scope );
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return( -1 );
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}
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t[5] = vips_image_new_matrixv( 2, 2,
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-1.0, -1.0,
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1.0, 1.0 );
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vips_image_set_double( t[5], "offset", 128.0 );
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if( vips_conv( in, Gy, t[5],
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"precision", VIPS_PRECISION_INTEGER,
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NULL ) ) {
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g_object_unref( scope );
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return( -1 );
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}
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g_object_unref( scope );
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return( 0 );
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}
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/* LUT for calculating atan2() with +/- 4 bits of precision in each axis.
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*/
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static VipsPel vips_canny_polar_atan2[256];
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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 gx = p1[band] - 128;
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int gy = p2[band] - 128;
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/* gx/gy are -128 to +127, we need -8 to +7
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* for the atan2 LUT.
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*/
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int i = ((gx >> 4) & 0xf) | (gy & 0xf0);
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/* We should calculate
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* 0.5 * sqrt( x * x + y * y )
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* ie. length of hypot, scaled down to avoid
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* clipping. We are only interested in relative
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* magnitude, so we can skip the sqrt and just
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* shift down 9 bits.
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*
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* Try "256 * (VIPS_DEG( atan2( gx, gy ) ) +
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* 360) / 360;" to test LUT.
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*/
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q[0] = (gx * gx + gy * gy + 256) >> 9;
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q[1] = vips_canny_polar_atan2[i];
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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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static void *
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||||||
|
vips_atan2_init( void *null )
|
||||||
|
{
|
||||||
|
int i;
|
||||||
|
|
||||||
|
for( i = 0; i < 256; i++ ) {
|
||||||
|
/* Use the bottom 4 bits for x, the top 4 for y. The double
|
||||||
|
* shift does sign extension, assuming 2s complement.
|
||||||
|
*/
|
||||||
|
int bits = sizeof( int ) * 8 - 4;
|
||||||
|
int x = ((i & 0xf) << bits) >> bits;
|
||||||
|
int y = ((i >> 4) & 0x0f) << bits >> bits;
|
||||||
|
double theta = VIPS_DEG( atan2( x, y ) ) + 360;
|
||||||
|
|
||||||
|
vips_canny_polar_atan2[i] = 256 * theta / 360;
|
||||||
|
}
|
||||||
|
|
||||||
|
return( NULL );
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Calculate G/theta from Gx/Gy -- rather like rect -> polar, except that we
|
||||||
|
* code theta as below. Scale G down by 0.5 so that we don't clip on hard
|
||||||
|
* edges.
|
||||||
|
*
|
||||||
|
* For a white disc on a black background, theta is 0 at the bottom, 64 on the
|
||||||
|
* right, 128 at the top and 192 on the left edge.
|
||||||
|
*/
|
||||||
|
static int
|
||||||
|
vips_canny_polar( VipsImage **args, VipsImage **out )
|
||||||
|
{
|
||||||
|
static GOnce once = G_ONCE_INIT;
|
||||||
|
|
||||||
|
g_once( &once, (GThreadFunc) vips_atan2_init, NULL );
|
||||||
|
|
||||||
|
*out = vips_image_new();
|
||||||
|
if( vips_image_pipeline_array( *out,
|
||||||
|
VIPS_DEMAND_STYLE_THINSTRIP, args ) )
|
||||||
|
return( -1 );
|
||||||
|
(*out)->Bands *= 2;
|
||||||
|
|
||||||
|
if( vips_image_generate( *out,
|
||||||
|
vips_start_many, vips_canny_polar_generate, vips_stop_many,
|
||||||
|
args, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
static int
|
||||||
|
vips_canny_nonmax_generate( VipsRegion *or,
|
||||||
|
void *vseq, void *a, void *b, gboolean *stop )
|
||||||
|
{
|
||||||
|
VipsRegion *in = (VipsRegion *) vseq;
|
||||||
|
VipsRect *r = &or->valid;
|
||||||
|
VipsImage *im = in->im;
|
||||||
|
int out_bands = or->im->Bands;
|
||||||
|
|
||||||
|
VipsRect rect;
|
||||||
|
int x, y, band;
|
||||||
|
int lsk;
|
||||||
|
int psk;
|
||||||
|
int offseta[4];
|
||||||
|
int offsetb[4];
|
||||||
|
|
||||||
|
rect = *r;
|
||||||
|
rect.width += 2;
|
||||||
|
rect.height += 2;
|
||||||
|
if( vips_region_prepare( in, &rect ) )
|
||||||
|
return( -1 );
|
||||||
|
lsk = VIPS_REGION_LSKIP( in );
|
||||||
|
psk = VIPS_IMAGE_SIZEOF_PEL( im );
|
||||||
|
|
||||||
|
/* For each of the four directions, the offset to get to that pixel
|
||||||
|
* from the top-left of our 3x3. offseta is the left/up direction, or
|
||||||
|
* the lower memory address.
|
||||||
|
*
|
||||||
|
* 1 | 0 | 3
|
||||||
|
* --+---+--
|
||||||
|
* 2 | X | 2
|
||||||
|
* --+---+--
|
||||||
|
* 3 | 0 | 1
|
||||||
|
*/
|
||||||
|
offseta[0] = psk;
|
||||||
|
offsetb[0] = psk + 2 * lsk;
|
||||||
|
offseta[1] = 0;
|
||||||
|
offsetb[1] = 2 * psk + 2 * lsk;
|
||||||
|
offseta[2] = lsk;
|
||||||
|
offsetb[2] = 2 * psk + lsk;
|
||||||
|
offseta[3] = 2 * psk;
|
||||||
|
offsetb[3] = 2 * lsk;
|
||||||
|
|
||||||
|
for( y = 0; y < r->height; y++ ) {
|
||||||
|
VipsPel *p = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( in, r->left, r->top + y );
|
||||||
|
VipsPel *q = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( or, r->left, r->top + y );
|
||||||
|
|
||||||
|
for( x = 0; x < r->width; x++ ) {
|
||||||
|
for( band = 0; band < out_bands; band++ ) {
|
||||||
|
int G = p[lsk + psk];
|
||||||
|
int theta = p[lsk + psk + 1];
|
||||||
|
int a = ((theta + 16) / 32) & 0x3;
|
||||||
|
VipsPel low = p[offseta[a]];
|
||||||
|
VipsPel high = p[offsetb[a]];
|
||||||
|
|
||||||
|
/* Set G to 0 if it's not the local maxima in
|
||||||
|
* the direction of the gradient. If G is equal
|
||||||
|
* to the low side, also zero, so wide edges
|
||||||
|
* with equal gradient move (arbitarilly) left
|
||||||
|
* and up.
|
||||||
|
*/
|
||||||
|
if( G <= low ||
|
||||||
|
G < high )
|
||||||
|
G = 0;
|
||||||
|
|
||||||
|
q[band] = G;
|
||||||
|
|
||||||
|
p += 2;
|
||||||
|
}
|
||||||
|
|
||||||
|
q += out_bands;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Remove non-maximal edges. At each point, compare the G to the G in either
|
||||||
|
* direction and 0 it if it's not the largest.
|
||||||
|
*/
|
||||||
|
static int
|
||||||
|
vips_canny_nonmax( VipsImage *in, VipsImage **out )
|
||||||
|
{
|
||||||
|
*out = vips_image_new();
|
||||||
|
if( vips_image_pipelinev( *out,
|
||||||
|
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
(*out)->Bands /= 2;
|
||||||
|
(*out)->Xsize -= 2;
|
||||||
|
(*out)->Ysize -= 2;
|
||||||
|
|
||||||
|
if( vips_image_generate( *out,
|
||||||
|
vips_start_one, vips_canny_nonmax_generate, vips_stop_one,
|
||||||
|
in, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
static int
|
||||||
|
vips_canny_nonmaxi_generate( VipsRegion *or,
|
||||||
|
void *vseq, void *a, void *b, gboolean *stop )
|
||||||
|
{
|
||||||
|
VipsRegion *in = (VipsRegion *) vseq;
|
||||||
|
VipsRect *r = &or->valid;
|
||||||
|
VipsImage *im = in->im;
|
||||||
|
int out_bands = or->im->Bands;
|
||||||
|
|
||||||
|
VipsRect rect;
|
||||||
|
int x, y, band;
|
||||||
|
int lsk;
|
||||||
|
int psk;
|
||||||
|
|
||||||
|
int offset[8];
|
||||||
|
|
||||||
|
rect = *r;
|
||||||
|
rect.width += 2;
|
||||||
|
rect.height += 2;
|
||||||
|
if( vips_region_prepare( in, &rect ) )
|
||||||
|
return( -1 );
|
||||||
|
lsk = VIPS_REGION_LSKIP( in );
|
||||||
|
psk = VIPS_IMAGE_SIZEOF_PEL( im );
|
||||||
|
|
||||||
|
/* For each of the 8 directions, the offset to get to that pixel from
|
||||||
|
* the top-left of the 3x3.
|
||||||
|
*
|
||||||
|
* 5 | 4 | 3
|
||||||
|
* --+---+--
|
||||||
|
* 6 | X | 2
|
||||||
|
* --+---+--
|
||||||
|
* 7 | 0 | 1
|
||||||
|
*/
|
||||||
|
offset[0] = psk + 2 * lsk;
|
||||||
|
offset[1] = 2 * psk + 2 * lsk;
|
||||||
|
offset[2] = 2 * psk + lsk;
|
||||||
|
offset[3] = 2 * psk;
|
||||||
|
offset[4] = psk;
|
||||||
|
offset[5] = 0;
|
||||||
|
offset[6] = lsk;
|
||||||
|
offset[7] = 2 * lsk;
|
||||||
|
|
||||||
|
for( y = 0; y < r->height; y++ ) {
|
||||||
|
VipsPel *p = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( in, r->left, r->top + y );
|
||||||
|
VipsPel *q = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( or, r->left, r->top + y );
|
||||||
|
|
||||||
|
for( x = 0; x < r->width; x++ ) {
|
||||||
|
for( band = 0; band < out_bands; band++ ) {
|
||||||
|
int G = p[lsk + psk];
|
||||||
|
int theta = p[lsk + psk + 1];
|
||||||
|
int low_theta = (theta / 32) & 0x7;
|
||||||
|
int high_theta = (low_theta + 1) & 0x7;
|
||||||
|
int residual = theta - low_theta * 32;
|
||||||
|
int lowa = p[offset[low_theta]];
|
||||||
|
int lowb = p[offset[high_theta]];
|
||||||
|
int low = (lowa * (32 - residual) +
|
||||||
|
lowb * residual) / 32;
|
||||||
|
int higha = p[offset[(low_theta + 4) & 0x7]];
|
||||||
|
int highb = p[offset[(high_theta + 4) & 0x7]];
|
||||||
|
int high = (higha * (32 - residual) +
|
||||||
|
highb * residual) / 32;
|
||||||
|
|
||||||
|
#ifdef DEBUG
|
||||||
|
if( G > 0 ) {
|
||||||
|
int i, j;
|
||||||
|
|
||||||
|
printf( "Gradient:\n" );
|
||||||
|
for( j = 0; j < 3; j++ ) {
|
||||||
|
for( i = 0; i < 3; i++ )
|
||||||
|
printf( "%3d ", p[j * lsk + i * psk] );
|
||||||
|
printf("\n");
|
||||||
|
}
|
||||||
|
|
||||||
|
printf( "Theta:\n" );
|
||||||
|
for( j = 0; j < 3; j++ ) {
|
||||||
|
for( i = 0; i < 3; i++ )
|
||||||
|
printf( "%3d ", p[j * lsk + i * psk + 1] );
|
||||||
|
printf("\n");
|
||||||
|
}
|
||||||
|
|
||||||
|
printf( "G = %d\n", G );
|
||||||
|
printf( "theta = %d\n", theta );
|
||||||
|
printf( "low_theta = %d\n", low_theta );
|
||||||
|
printf( "high_theta = %d\n", high_theta );
|
||||||
|
printf( "residual = %d\n", residual );
|
||||||
|
printf( "lowa = %d\n", lowa );
|
||||||
|
printf( "lowb = %d\n", lowb );
|
||||||
|
printf( "low = %d\n", low );
|
||||||
|
printf( "higha = %d\n", higha );
|
||||||
|
printf( "highb = %d\n", highb );
|
||||||
|
printf( "high = %d\n", high );
|
||||||
|
if( G <= low || G < high )
|
||||||
|
printf( "thin\n" );
|
||||||
|
printf( "\n" );
|
||||||
|
}
|
||||||
|
#endif /*DEBUG*/
|
||||||
|
|
||||||
|
/* Set G to 0 if it's not the local maxima in
|
||||||
|
* the direction of the gradient.
|
||||||
|
*/
|
||||||
|
if( G <= low ||
|
||||||
|
G < high )
|
||||||
|
G = 0;
|
||||||
|
|
||||||
|
q[band] = G;
|
||||||
|
|
||||||
|
p += 2;
|
||||||
|
}
|
||||||
|
|
||||||
|
q += out_bands;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
/* Remove non-maximal edges. At each point, compare the G to the G in either
|
||||||
|
* direction and 0 it if it's not the largest.
|
||||||
|
*/
|
||||||
|
static int
|
||||||
|
vips_canny_nonmaxi( VipsImage *in, VipsImage **out )
|
||||||
|
{
|
||||||
|
*out = vips_image_new();
|
||||||
|
if( vips_image_pipelinev( *out,
|
||||||
|
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
(*out)->Bands /= 2;
|
||||||
|
(*out)->Xsize -= 2;
|
||||||
|
(*out)->Ysize -= 2;
|
||||||
|
|
||||||
|
if( vips_image_generate( *out,
|
||||||
|
vips_start_one, vips_canny_nonmaxi_generate, vips_stop_one,
|
||||||
|
in, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
static int
|
||||||
|
vips_canny_thresh_generate( VipsRegion *or,
|
||||||
|
void *vseq, void *a, void *b, gboolean *stop )
|
||||||
|
{
|
||||||
|
VipsRegion *in = (VipsRegion *) vseq;
|
||||||
|
VipsCanny *canny = (VipsCanny *) b;
|
||||||
|
VipsRect *r = &or->valid;
|
||||||
|
int sz = r->width * in->im->Bands;
|
||||||
|
VipsPel low = canny->low;
|
||||||
|
VipsPel high = canny->high;
|
||||||
|
|
||||||
|
int x, y;
|
||||||
|
|
||||||
|
if( vips_region_prepare( in, r ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
for( y = 0; y < r->height; y++ ) {
|
||||||
|
VipsPel *p = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( in, r->left, r->top + y );
|
||||||
|
VipsPel *q = (VipsPel * restrict)
|
||||||
|
VIPS_REGION_ADDR( or, r->left, r->top + y );
|
||||||
|
|
||||||
|
for( x = 0; x < sz; x++ ) {
|
||||||
|
int v;
|
||||||
|
|
||||||
|
v = p[x];
|
||||||
|
if( v <= low )
|
||||||
|
v = 0;
|
||||||
|
else if( v <= high )
|
||||||
|
v = 128;
|
||||||
|
else
|
||||||
|
v = 255;
|
||||||
|
|
||||||
|
q[x] = v;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
static int
|
||||||
|
vips_canny_thresh( VipsCanny *canny, VipsImage *in, VipsImage **out )
|
||||||
|
{
|
||||||
|
*out = vips_image_new();
|
||||||
|
if( vips_image_pipelinev( *out,
|
||||||
|
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
if( vips_image_generate( *out,
|
||||||
|
vips_start_one, vips_canny_thresh_generate, vips_stop_one,
|
||||||
|
in, canny ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
static int
|
||||||
|
vips_canny_build( VipsObject *object )
|
||||||
|
{
|
||||||
|
VipsCanny *canny = (VipsCanny *) object;
|
||||||
|
VipsImage **t = (VipsImage **) vips_object_local_array( object, 20 );
|
||||||
|
|
||||||
|
VipsImage *in;
|
||||||
|
VipsImage *Gx;
|
||||||
|
VipsImage *Gy;
|
||||||
|
|
||||||
|
if( VIPS_OBJECT_CLASS( vips_canny_parent_class )->build( object ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
in = canny->in;
|
||||||
|
|
||||||
|
if( vips_gaussblur( in, &t[0], canny->sigma, NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
in = t[0];
|
||||||
|
|
||||||
|
if( vips_canny_gradient_simple( in, &Gx, &Gy ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
/* Form (G, theta), with theta coded.
|
||||||
|
*/
|
||||||
|
canny->args[0] = Gx;
|
||||||
|
canny->args[1] = Gy;
|
||||||
|
canny->args[2] = NULL;
|
||||||
|
if( vips_canny_polar( canny->args, &t[9] ) )
|
||||||
|
return( -1 );
|
||||||
|
in = t[9];
|
||||||
|
|
||||||
|
/* Expand by two pixels all around, then thin.
|
||||||
|
*/
|
||||||
|
if( vips_embed( in, &t[10], 1, 1, in->Xsize + 2, in->Ysize + 2,
|
||||||
|
"extend", VIPS_EXTEND_COPY,
|
||||||
|
NULL ) )
|
||||||
|
return( -1 );
|
||||||
|
if( canny->interpolate ) {
|
||||||
|
if( vips_canny_nonmaxi( t[10], &t[11] ) )
|
||||||
|
return( -1 );
|
||||||
|
}
|
||||||
|
else {
|
||||||
|
if( vips_canny_nonmax( t[10], &t[11] ) )
|
||||||
|
return( -1 );
|
||||||
|
}
|
||||||
|
in = t[11];
|
||||||
|
|
||||||
|
/* Double threshold.
|
||||||
|
*/
|
||||||
|
if( vips_canny_thresh( canny, in, &t[12] ) )
|
||||||
|
return( -1 );
|
||||||
|
in = t[12];
|
||||||
|
|
||||||
|
g_object_set( object, "out", vips_image_new(), NULL );
|
||||||
|
|
||||||
|
if( vips_image_write( in, canny->out ) )
|
||||||
|
return( -1 );
|
||||||
|
|
||||||
|
return( 0 );
|
||||||
|
}
|
||||||
|
|
||||||
|
static void
|
||||||
|
vips_canny_class_init( VipsCannyClass *class )
|
||||||
|
{
|
||||||
|
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
|
||||||
|
VipsObjectClass *object_class = (VipsObjectClass *) class;
|
||||||
|
VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
|
||||||
|
|
||||||
|
gobject_class->set_property = vips_object_set_property;
|
||||||
|
gobject_class->get_property = vips_object_get_property;
|
||||||
|
|
||||||
|
object_class->nickname = "canny";
|
||||||
|
object_class->description = _( "gaussian blur" );
|
||||||
|
object_class->build = vips_canny_build;
|
||||||
|
|
||||||
|
operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
|
||||||
|
|
||||||
|
VIPS_ARG_IMAGE( class, "in", 1,
|
||||||
|
_( "Input" ),
|
||||||
|
_( "Input image" ),
|
||||||
|
VIPS_ARGUMENT_REQUIRED_INPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, in ) );
|
||||||
|
|
||||||
|
VIPS_ARG_IMAGE( class, "out", 2,
|
||||||
|
_( "Output" ),
|
||||||
|
_( "Output image" ),
|
||||||
|
VIPS_ARGUMENT_REQUIRED_OUTPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, out ) );
|
||||||
|
|
||||||
|
VIPS_ARG_DOUBLE( class, "sigma", 10,
|
||||||
|
_( "Sigma" ),
|
||||||
|
_( "Sigma of Gaussian" ),
|
||||||
|
VIPS_ARGUMENT_OPTIONAL_INPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, sigma ),
|
||||||
|
0.01, 1000, 1.4 );
|
||||||
|
|
||||||
|
VIPS_ARG_DOUBLE( class, "low", 11,
|
||||||
|
_( "Low" ),
|
||||||
|
_( "Low threshold" ),
|
||||||
|
VIPS_ARGUMENT_OPTIONAL_INPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, low ),
|
||||||
|
-INFINITY, INFINITY, 3.0 );
|
||||||
|
|
||||||
|
VIPS_ARG_DOUBLE( class, "high", 12,
|
||||||
|
_( "High" ),
|
||||||
|
_( "High threshold" ),
|
||||||
|
VIPS_ARGUMENT_OPTIONAL_INPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, high ),
|
||||||
|
-INFINITY, INFINITY, 7.0 );
|
||||||
|
|
||||||
|
VIPS_ARG_BOOL( class, "interpolate", 13,
|
||||||
|
_( "Interpolate" ),
|
||||||
|
_( "Interpolate gradient angles" ),
|
||||||
|
VIPS_ARGUMENT_OPTIONAL_INPUT,
|
||||||
|
G_STRUCT_OFFSET( VipsCanny, interpolate ),
|
||||||
|
FALSE );
|
||||||
|
|
||||||
|
}
|
||||||
|
|
||||||
|
static void
|
||||||
|
vips_canny_init( VipsCanny *canny )
|
||||||
|
{
|
||||||
|
canny->sigma = 1.4;
|
||||||
|
canny->low = 3.0;
|
||||||
|
canny->high = 7.0;
|
||||||
|
}
|
||||||
|
|
||||||
|
/**
|
||||||
|
* vips_canny: (method)
|
||||||
|
* @in: input image
|
||||||
|
* @out: (out): output image
|
||||||
|
* @sigma: how large a mask to use
|
||||||
|
* @...: %NULL-terminated list of optional named arguments
|
||||||
|
*
|
||||||
|
* Optional arguments:
|
||||||
|
*
|
||||||
|
* * @sigma: %gdouble, sigma for gaussian blur
|
||||||
|
*
|
||||||
|
* See also: vips_gaussblur().
|
||||||
|
*
|
||||||
|
* Returns: 0 on success, -1 on error.
|
||||||
|
*/
|
||||||
|
int
|
||||||
|
vips_canny( VipsImage *in, VipsImage **out, ... )
|
||||||
|
{
|
||||||
|
va_list ap;
|
||||||
|
int result;
|
||||||
|
|
||||||
|
va_start( ap, out );
|
||||||
|
result = vips_call_split( "canny", ap, in, out );
|
||||||
|
va_end( ap );
|
||||||
|
|
||||||
|
return( result );
|
||||||
|
}
|
||||||
Loading…
x
Reference in New Issue
Block a user