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add a fast uchar sobel

This commit is contained in:
John Cupitt 2018-02-27 18:19:07 +00:00
parent d5aabaa23e
commit bf70c49fa5
1 changed files with 105 additions and 4 deletions
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109
libvips/convolution/sobel.c
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@ -57,6 +57,9 @@ typedef struct _VipsSobel {
VipsImage *in;
VipsImage *out;
/* Need an image vector for start_many.
*/
VipsImage *args[3];
} VipsSobel;
typedef VipsOperationClass VipsSobelClass;
@ -64,10 +67,91 @@ typedef VipsOperationClass VipsSobelClass;
G_DEFINE_TYPE( VipsSobel, vips_sobel, VIPS_TYPE_OPERATION );
static int
vips_sobel_build( VipsObject *object )
vips_sobel_uchar_gen( VipsRegion *or,
void *vseq, void *a, void *b, gboolean *stop )
{
VipsSobel *sobel = (VipsSobel *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 20 );
VipsRegion **in = (VipsRegion **) vseq;
VipsRect *r = &or->valid;
int sz = r->width * in[0]->im->Bands;
int x, y;
if( vips_reorder_prepare_many( or->im, in, r ) )
return( -1 );
for( y = 0; y < r->height; y++ ) {
VipsPel *p1 = (VipsPel * restrict)
VIPS_REGION_ADDR( in[0], r->left, r->top + y );
VipsPel *p2 = (VipsPel * restrict)
VIPS_REGION_ADDR( in[1], 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 v1 = p1[x] - 128;
int v2 = p2[x] - 128;
q[x] = VIPS_ABS( v1 ) + VIPS_ABS( v2 );
}
}
return( 0 );
}
/* Fast uchar path.
*/
static int
vips_sobel_build_uchar( VipsSobel *sobel )
{
VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( sobel ), 20 );
t[1] = vips_image_new_matrixv( 1, 3, 1.0, 2.0, 1.0 );
t[2] = vips_image_new_matrixv( 3, 1, 1.0, 0.0, -1.0 );
vips_image_set_double( t[2], "offset", 128.0 );
if( vips_conv( sobel->in, &t[3], t[1],
"precision", VIPS_PRECISION_INTEGER,
NULL ) ||
vips_conv( t[3], &t[4], t[2],
"precision", VIPS_PRECISION_INTEGER,
NULL ) )
return( -1 );
t[5] = vips_image_new_matrixv( 3, 1, 1.0, 2.0, 1.0 );
t[6] = vips_image_new_matrixv( 1, 3, 1.0, 0.0, -1.0 );
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,
NULL ) )
return( -1 );
g_object_set( sobel, "out", vips_image_new(), NULL );
sobel->args[0] = t[4];
sobel->args[1] = t[8];
sobel->args[2] = NULL;
if( vips_image_pipeline_array( sobel->out,
VIPS_DEMAND_STYLE_THINSTRIP, sobel->args ) )
return( -1 );
if( vips_image_generate( sobel->out,
vips_start_many, vips_sobel_uchar_gen, vips_stop_many,
sobel->args, NULL ) )
return( -1 );
return( 0 );
}
/* Works for any format, but slower.
*/
static int
vips_sobel_build_float( VipsSobel *sobel )
{
VipsImage **t = (VipsImage **)
vips_object_local_array( VIPS_OBJECT( sobel ), 20 );
t[1] = vips_image_new_matrixv( 1, 3, 1.0, 2.0, 1.0 );
t[2] = vips_image_new_matrixv( 3, 1, 1.0, 0.0, -1.0 );
@ -87,7 +171,7 @@ vips_sobel_build( VipsObject *object )
vips_cast( t[11], &t[12], sobel->in->BandFmt, NULL ) )
return( -1 );
g_object_set( object, "out", vips_image_new(), NULL );
g_object_set( sobel, "out", vips_image_new(), NULL );
if( vips_image_write( t[12], sobel->out ) )
return( -1 );
@ -95,6 +179,23 @@ vips_sobel_build( VipsObject *object )
return( 0 );
}
static int
vips_sobel_build( VipsObject *object )
{
VipsSobel *sobel = (VipsSobel *) object;
if( sobel->in->BandFmt == VIPS_FORMAT_UCHAR ) {
if( vips_sobel_build_uchar( sobel ) )
return( -1 );
}
else {
if( vips_sobel_build_float( sobel ) )
return( -1 );
}
return( 0 );
}
static void
vips_sobel_class_init( VipsSobelClass *class )
{