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sobel done

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This commit is contained in:
John Cupitt 2018-02-28 22:51:31 +00:00
parent bf70c49fa5
commit bc0b8ba5c1
1 changed files with 36 additions and 41 deletions
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77
libvips/convolution/sobel.c
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@ -46,11 +46,6 @@
#include <vips/vips.h> #include <vips/vips.h>
/* TODO
* - check sobel speed with separated and non-sep masks
* - add an 8-bit sobel path, with offset 128 and code for abs() + abs()
*/
typedef struct _VipsSobel { typedef struct _VipsSobel {
VipsOperation parent_instance; VipsOperation parent_instance;
@ -88,10 +83,11 @@ vips_sobel_uchar_gen( VipsRegion *or,
VIPS_REGION_ADDR( or, r->left, r->top + y ); VIPS_REGION_ADDR( or, r->left, r->top + y );
for( x = 0; x < sz; x++ ) { for( x = 0; x < sz; x++ ) {
int v1 = p1[x] - 128; int v1 = 2 * (p1[x] - 128);
int v2 = p2[x] - 128; int v2 = 2 * (p2[x] - 128);
int v = VIPS_ABS( v1 ) + VIPS_ABS( v2 );
q[x] = VIPS_ABS( v1 ) + VIPS_ABS( v2 ); q[x] = v > 255 ? 255 : v;
} }
} }
@ -106,35 +102,38 @@ vips_sobel_build_uchar( VipsSobel *sobel )
VipsImage **t = (VipsImage **) VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( sobel ), 20 ); vips_object_local_array( VIPS_OBJECT( sobel ), 20 );
t[1] = vips_image_new_matrixv( 1, 3, 1.0, 2.0, 1.0 ); g_info( "vips_sobel: uchar path" );
t[2] = vips_image_new_matrixv( 3, 1, 1.0, 0.0, -1.0 );
vips_image_set_double( t[2], "offset", 128.0 ); /* Sobel is separable, but it's so small there's no speed to be gained,
* and doing it one pass lets us keep more precision.
*
* Divide the result by 2 to prevent overflow, since our result will be
* just 8 bits.
*/
t[1] = vips_image_new_matrixv( 3, 3,
1.0, 2.0, 1.0,
0.0, 0.0, 0.0,
-1.0, -2.0, -1.0 );
vips_image_set_double( t[1], "offset", 128.0 );
vips_image_set_double( t[1], "scale", 2.0 );
if( vips_conv( sobel->in, &t[3], t[1], if( vips_conv( sobel->in, &t[3], t[1],
"precision", VIPS_PRECISION_INTEGER, "precision", VIPS_PRECISION_INTEGER,
NULL ) || NULL ) )
vips_conv( t[3], &t[4], t[2],
"precision", VIPS_PRECISION_INTEGER,
NULL ) )
return( -1 ); return( -1 );
t[5] = vips_image_new_matrixv( 3, 1, 1.0, 2.0, 1.0 ); if( vips_rot90( t[1], &t[5], NULL ) ||
t[6] = vips_image_new_matrixv( 1, 3, 1.0, 0.0, -1.0 ); vips_conv( sobel->in, &t[7], t[5],
vips_image_set_double( t[6], "offset", 128.0 );
if( vips_conv( sobel->in, &t[7], t[5],
"precision", VIPS_PRECISION_INTEGER,
NULL ) ||
vips_conv( t[7], &t[8], t[6],
"precision", VIPS_PRECISION_INTEGER, "precision", VIPS_PRECISION_INTEGER,
NULL ) ) NULL ) )
return( -1 ); return( -1 );
g_object_set( sobel, "out", vips_image_new(), NULL ); g_object_set( sobel, "out", vips_image_new(), NULL );
sobel->args[0] = t[4]; sobel->args[0] = t[3];
sobel->args[1] = t[8]; sobel->args[1] = t[7];
sobel->args[2] = NULL; sobel->args[2] = NULL;
if( vips_image_pipeline_array( sobel->out, if( vips_image_pipeline_array( sobel->out,
VIPS_DEMAND_STYLE_THINSTRIP, sobel->args ) ) VIPS_DEMAND_STYLE_FATSTRIP, sobel->args ) )
return( -1 ); return( -1 );
if( vips_image_generate( sobel->out, if( vips_image_generate( sobel->out,
@ -153,20 +152,19 @@ vips_sobel_build_float( VipsSobel *sobel )
VipsImage **t = (VipsImage **) VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( sobel ), 20 ); vips_object_local_array( VIPS_OBJECT( sobel ), 20 );
t[1] = vips_image_new_matrixv( 1, 3, 1.0, 2.0, 1.0 ); g_info( "vips_sobel: float path" );
t[2] = vips_image_new_matrixv( 3, 1, 1.0, 0.0, -1.0 );
if( vips_conv( sobel->in, &t[3], t[1], NULL ) || t[1] = vips_image_new_matrixv( 3, 3,
vips_conv( t[3], &t[4], t[2], NULL ) ) 1.0, 2.0, 1.0,
0.0, 0.0, 0.0,
-1.0, -2.0, -1.0 );
if( vips_rot90( t[1], &t[2], NULL ) ||
vips_conv( sobel->in, &t[3], t[1], NULL ) ||
vips_conv( sobel->in, &t[7], t[2], NULL ) )
return( -1 ); return( -1 );
t[5] = vips_image_new_matrixv( 3, 1, 1.0, 2.0, 1.0 ); if( vips_abs( t[3], &t[9], NULL ) ||
t[6] = vips_image_new_matrixv( 1, 3, 1.0, 0.0, -1.0 ); vips_abs( t[7], &t[10], NULL ) ||
if( vips_conv( sobel->in, &t[7], t[5], NULL ) ||
vips_conv( t[7], &t[8], t[6], NULL ) )
return( -1 );
if( vips_abs( t[4], &t[9], NULL ) ||
vips_abs( t[8], &t[10], NULL ) ||
vips_add( t[9], t[10], &t[11], NULL ) || vips_add( t[9], t[10], &t[11], NULL ) ||
vips_cast( t[11], &t[12], sobel->in->BandFmt, NULL ) ) vips_cast( t[11], &t[12], sobel->in->BandFmt, NULL ) )
return( -1 ); return( -1 );
@ -201,7 +199,6 @@ vips_sobel_class_init( VipsSobelClass *class )
{ {
GObjectClass *gobject_class = G_OBJECT_CLASS( class ); GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *object_class = (VipsObjectClass *) class; VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
gobject_class->set_property = vips_object_set_property; gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property; gobject_class->get_property = vips_object_get_property;
@ -210,8 +207,6 @@ vips_sobel_class_init( VipsSobelClass *class )
object_class->description = _( "Sobel edge detector" ); object_class->description = _( "Sobel edge detector" );
object_class->build = vips_sobel_build; object_class->build = vips_sobel_build;
operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
VIPS_ARG_IMAGE( class, "in", 1, VIPS_ARG_IMAGE( class, "in", 1,
_( "Input" ), _( "Input" ),
_( "Input image" ), _( "Input image" ),