fix jaggies on the edge of affine output

and add a "background" param

ChangeLog

@@ -35,6 +35,8 @@
 - add vips_fill_nearest() ... fill pixels with nearest colour
 - add VIPS_COMBINE_MIN, a new combining mode for vips_compass()
 - vips_hist_find_indexed() now has a @combine parameter
+- vips_affine() and vips_similarity() have a "background" parameter
+- fix nasty jaggies on the edge of affine output
 
 29/8/17 started 8.5.9
 - make --fail stop jpeg read on any libjpeg warning, thanks @mceachen

libvips/include/vips/private.h

@@ -162,7 +162,7 @@ void vips__region_no_ownership( struct _VipsRegion *reg );
 
 typedef int (*VipsRegionFillFn)( struct _VipsRegion *, void * );
 int vips_region_fill( struct _VipsRegion *reg, 
-	VipsRect *r, VipsRegionFillFn fn, void *a );
+	const VipsRect *r, VipsRegionFillFn fn, void *a );
 
 int vips__image_wio_output( struct _VipsImage *image );
 int vips__image_pio_output( struct _VipsImage *image );
@@ -185,7 +185,7 @@ void vips_region_dump_all( void );
  */
 int vips__init( const char *argv0 );
 size_t vips__get_sizeof_vipsobject( void );
-int vips_region_prepare_many( struct _VipsRegion **reg, VipsRect *r );
+int vips_region_prepare_many( struct _VipsRegion **reg, const VipsRect *r );
 
 /* Handy for debugging.
  */

libvips/include/vips/region.h

@@ -104,23 +104,25 @@ GType vips_region_get_type(void);
 
 VipsRegion *vips_region_new( VipsImage *image );
 
-int vips_region_buffer( VipsRegion *reg, VipsRect *r );
+int vips_region_buffer( VipsRegion *reg, const VipsRect *r );
-int vips_region_image( VipsRegion *reg, VipsRect *r );
+int vips_region_image( VipsRegion *reg, const VipsRect *r );
 int vips_region_region( VipsRegion *reg, VipsRegion *dest, 
-	VipsRect *r, int x, int y );
+	const VipsRect *r, int x, int y );
 int vips_region_equalsregion( VipsRegion *reg1, VipsRegion *reg2 );
 int vips_region_position( VipsRegion *reg, int x, int y );
 
-void vips_region_paint( VipsRegion *reg, VipsRect *r, int value );
+void vips_region_paint( VipsRegion *reg, const VipsRect *r, int value );
-void vips_region_paint_pel( VipsRegion *reg, VipsRect *r, VipsPel *ink );
+void vips_region_paint_pel( VipsRegion *reg, 
+	const VipsRect *r, const VipsPel *ink );
 void vips_region_black( VipsRegion *reg );
 void vips_region_copy( VipsRegion *reg, VipsRegion *dest, 
-	VipsRect *r, int x, int y );
+	const VipsRect *r, int x, int y );
-int vips_region_shrink( VipsRegion *from, VipsRegion *to, VipsRect *target );
+int vips_region_shrink( VipsRegion *from, 
+	VipsRegion *to, const VipsRect *target );
 
-int vips_region_prepare( VipsRegion *reg, VipsRect *r );
+int vips_region_prepare( VipsRegion *reg, const VipsRect *r );
 int vips_region_prepare_to( VipsRegion *reg, 
-	VipsRegion *dest, VipsRect *r, int x, int y );
+	VipsRegion *dest, const VipsRect *r, int x, int y );
 
 void vips_region_invalidate( VipsRegion *reg );
 

libvips/iofuncs/region.c

@@ -563,7 +563,7 @@ vips_region_new( VipsImage *image )
  * Returns: 0 on success, or -1 for error.
  */
 int
-vips_region_buffer( VipsRegion *reg, VipsRect *r )
+vips_region_buffer( VipsRegion *reg, const VipsRect *r )
 {
 	VipsImage *im = reg->im;
 
@@ -626,14 +626,14 @@ vips_region_buffer( VipsRegion *reg, VipsRect *r )
  * @reg: region to operate upon
  * @r: #VipsRect of pixels you need to be able to address
  *
- * The region is transformed so that at least @r pixels are available to be read from
+ * The region is transformed so that at least @r pixels are available to be 
- * image. The image needs to be a memory buffer or represent a file
+ * read from the image. The image needs to be a memory buffer or represent a 
- * on disc that has been mapped or can be mapped. 
+ * file on disc that has been mapped or can be mapped. 
  *
  * Returns: 0 on success, or -1 for error.
  */
 int
-vips_region_image( VipsRegion *reg, VipsRect *r )
+vips_region_image( VipsRegion *reg, const VipsRect *r )
 {
 	VipsImage *image = reg->im;
 
@@ -725,16 +725,15 @@ vips_region_image( VipsRegion *reg, VipsRect *r )
  * Performs all clipping necessary to ensure that @reg->valid is indeed
  * valid.
  *
- * If the region we attach to is moved or destroyed, we can be left with dangling 
+ * If the region we attach to is moved or destroyed, we can be left with 
- * pointers! If the region we attach to is on another image, the two images 
+ * dangling pointers! If the region we attach to is on another image, the 
- * must have 
+ * two images must have the same sizeof( pel ).
- * the same sizeof( pel ).
  *
  * Returns: 0 on success, or -1 for error.
  */
 int
 vips_region_region( VipsRegion *reg, 
-	VipsRegion *dest, VipsRect *r, int x, int y )
+	VipsRegion *dest, const VipsRect *r, int x, int y )
 {
 	VipsRect image;
 	VipsRect wanted;
@@ -885,7 +884,8 @@ vips_region_position( VipsRegion *reg, int x, int y )
 }
 
 int
-vips_region_fill( VipsRegion *reg, VipsRect *r, VipsRegionFillFn fn, void *a )
+vips_region_fill( VipsRegion *reg, 
+	const VipsRect *r, VipsRegionFillFn fn, void *a )
 {
 	g_assert( reg->im->dtype == VIPS_IMAGE_PARTIAL );
 	g_assert( reg->im->generate_fn );
@@ -947,7 +947,7 @@ vips_region_fill( VipsRegion *reg, VipsRect *r, VipsRegionFillFn fn, void *a )
  * See also: vips_region_black().
  */
 void
-vips_region_paint( VipsRegion *reg, VipsRect *r, int value )
+vips_region_paint( VipsRegion *reg, const VipsRect *r, int value )
 {
 	VipsRect clipped;
 
@@ -1011,7 +1011,7 @@ vips_region_paint( VipsRegion *reg, VipsRect *r, int value )
  * See also: vips_region_paint().
  */
 void
-vips_region_paint_pel( VipsRegion *reg, VipsRect *r, VipsPel *ink )
+vips_region_paint_pel( VipsRegion *reg, const VipsRect *r, const VipsPel *ink )
 {
 	VipsRect ovl;
 
@@ -1076,7 +1076,8 @@ vips_region_black( VipsRegion *reg )
  * See also: vips_region_paint().
  */
 void
-vips_region_copy( VipsRegion *reg, VipsRegion *dest, VipsRect *r, int x, int y )
+vips_region_copy( VipsRegion *reg, 
+	VipsRegion *dest, const VipsRect *r, int x, int y )
 {
 	int z;
 	int len = VIPS_IMAGE_SIZEOF_PEL( reg->im ) * r->width;
@@ -1135,7 +1136,8 @@ vips_region_copy( VipsRegion *reg, VipsRegion *dest, VipsRect *r, int x, int y )
  * VIPS_CODING_LABQ only.
  */
 static void
-vips_region_shrink_labpack( VipsRegion *from, VipsRegion *to, VipsRect *target )
+vips_region_shrink_labpack( VipsRegion *from, 
+	VipsRegion *to, const VipsRect *target )
 {
 	int ls = VIPS_REGION_LSKIP( from );
 
@@ -1212,7 +1214,8 @@ vips_region_shrink_labpack( VipsRegion *from, VipsRegion *to, VipsRect *target )
 /* Generate area @target in @to using pixels in @from. Non-complex.
  */
 static void
-vips_region_shrink_uncoded( VipsRegion *from, VipsRegion *to, VipsRect *target )
+vips_region_shrink_uncoded( VipsRegion *from, 
+	VipsRegion *to, const VipsRect *target )
 {
 	int ls = VIPS_REGION_LSKIP( from );
 	int ps = VIPS_IMAGE_SIZEOF_PEL( from->im );
@@ -1295,7 +1298,8 @@ vips_region_shrink_uncoded( VipsRegion *from, VipsRegion *to, VipsRect *target )
  * last band as alpha.
  */
 static void
-vips_region_shrink_alpha( VipsRegion *from, VipsRegion *to, VipsRect *target )
+vips_region_shrink_alpha( VipsRegion *from, 
+	VipsRegion *to, const VipsRect *target )
 {
 	int ls = VIPS_REGION_LSKIP( from );
 	int nb = from->im->Bands;
@@ -1347,7 +1351,7 @@ vips_region_shrink_alpha( VipsRegion *from, VipsRegion *to, VipsRect *target )
  * See also: vips_region_copy().
  */
 int
-vips_region_shrink( VipsRegion *from, VipsRegion *to, VipsRect *target )
+vips_region_shrink( VipsRegion *from, VipsRegion *to, const VipsRect *target )
 {
 	VipsImage *image = from->im;
 
@@ -1419,7 +1423,7 @@ vips_region_generate( VipsRegion *reg )
  * Returns: 0 on success, or -1 on error.
  */
 int
-vips_region_prepare( VipsRegion *reg, VipsRect *r )
+vips_region_prepare( VipsRegion *reg, const VipsRect *r )
 {	
 	VipsImage *im = reg->im;
 
@@ -1492,7 +1496,7 @@ vips_region_prepare( VipsRegion *reg, VipsRect *r )
  */
 static int
 vips_region_prepare_to_generate( VipsRegion *reg, 
-	VipsRegion *dest, VipsRect *r, int x, int y )
+	VipsRegion *dest, const VipsRect *r, int x, int y )
 {
 	VipsImage *im = reg->im;
 	VipsPel *p;
@@ -1551,7 +1555,7 @@ vips_region_prepare_to_generate( VipsRegion *reg,
  */
 int
 vips_region_prepare_to( VipsRegion *reg, 
-	VipsRegion *dest, VipsRect *r, int x, int y )
+	VipsRegion *dest, const VipsRect *r, int x, int y )
 {
 	VipsImage *im = reg->im;
 	VipsRect image;
@@ -1686,7 +1690,7 @@ vips_region_prepare_to( VipsRegion *reg,
 /* Don't use this, use vips_reorder_prepare_many() instead.
  */
 int
-vips_region_prepare_many( VipsRegion **reg, VipsRect *r )
+vips_region_prepare_many( VipsRegion **reg, const VipsRect *r )
 {
 	for( ; *reg; ++reg )
 		if( vips_region_prepare( *reg, r ) )

libvips/resample/affine.c

@@ -1,6 +1,5 @@
 /* affine transform with a supplied interpolator.
  *
- * 
  * Copyright N. Dessipris
  * Written on: 01/11/1991
  * Modified on: 12/3/92 JC
@@ -84,6 +83,9 @@
  * 1/8/14
  * 	- revise transform ... again
  * 	- see new stress test in nip2/test/extras
+ * 7/11/17
+ * 	- add "background" parameter
+ * 	- better clipping means we have no jaggies on edges
  */
 
 /*
@@ -116,6 +118,7 @@
 /*
 #define DEBUG_VERBOSE
 #define DEBUG
+#define VIPS_DEBUG
  */
 
 #ifdef HAVE_CONFIG_H
@@ -149,6 +152,14 @@ typedef struct _VipsAffine {
 
 	VipsTransformation trn;
 
+	/* Background colour.
+	 */
+	VipsArrayDouble *background;
+
+	/* The [double] converted to the input image format.
+	 */
+	VipsPel *ink;
+
 } VipsAffine;
 
 typedef VipsResampleClass VipsAffineClass;
@@ -275,7 +286,7 @@ vips_affine_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 #endif /*DEBUG_VERBOSE*/
 
 	if( vips_rect_isempty( &clipped ) ) {
-		vips_region_black( or );
+		vips_region_paint_pel( or, r, affine->ink );
 		return( 0 );
 	}
 	if( vips_region_prepare( ir, &clipped ) )
@@ -336,9 +347,9 @@ vips_affine_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 			/* Clip against iarea.
 			 */
 			if( fx >= ile &&
-				fx < iri &&
+				fx <= iri &&
 				fy >= ito &&
-				fy < ibo ) {
+				fy <= ibo ) {
 				/* Verify that we can read the whole stencil.
 				 * With DEBUG on this will range-check.
 				 */
@@ -355,8 +366,10 @@ vips_affine_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 					q, ir, ix, iy );
 			}
 			else {
+				/* Out of range: paint the background.
+				 */
 				for( z = 0; z < ps; z++ ) 
-					q[z] = 0;
+					q[z] = affine->ink[z];
 			}
 
 			ix += ddx;
@@ -478,16 +491,36 @@ vips_affine_build( VipsObject *object )
 		return( -1 );
 	in = t[0];
 
+	/* Convert the background to the image's format.
+	 */
+	if( !(affine->ink = vips__vector_to_ink( class->nickname, 
+		resample->out,
+		VIPS_AREA( affine->background )->data, NULL, 
+		VIPS_AREA( affine->background )->n )) )
+		return( -1 );
+
 	/* Add new pixels around the input so we can interpolate at the edges.
+	 *
+	 * We add the interpolate stencil, plus one extra pixel on all the
+	 * edges. This means when we clip in generate (above) we can be sure 
+	 * we clip outside the real pixels and don't get jaggies on edges.
 	 */
 	if( vips_embed( in, &t[2], 
-		window_offset, window_offset, 
+		window_offset + 1, window_offset + 1, 
-		in->Xsize + window_size - 1, in->Ysize + window_size - 1,
+		in->Xsize + window_size - 1 + 2, 
-		"extend", VIPS_EXTEND_COPY,
+		in->Ysize + window_size - 1 + 2,
+		"extend", VIPS_EXTEND_BACKGROUND,
+		"background", affine->background,
 		NULL ) )
 		return( -1 );
 	in = t[2];
 
+	/* We've added a one-pixel border to the input: displace the transform
+	 * to compensate.
+	 */
+	affine->trn.idx -= 1;
+	affine->trn.idy -= 1;
+
 	/* Normally SMALLTILE ... except if this is strictly a size 
 	 * up/down affine.
 	 */
@@ -591,11 +624,19 @@ vips_affine_class_init( VipsAffineClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsAffine, idy ),
 		-10000000, 10000000, 0 );
+
+	VIPS_ARG_BOXED( class, "background", 2, 
+		_( "Background" ), 
+		_( "Background value" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsAffine, background ),
+		VIPS_TYPE_ARRAY_DOUBLE );
 }
 
 static void
 vips_affine_init( VipsAffine *affine )
 {
+	affine->background = vips_array_double_newv( 1, 0.0 );
 }
 
 /**
@@ -616,6 +657,7 @@ vips_affine_init( VipsAffine *affine )
  * * @idy: %gdouble, input vertical offset
  * * @odx: %gdouble, output horizontal offset
  * * @ody: %gdouble, output vertical offset
+ * * @background: #VipsArrayDouble colour for new pixels 
  *
  * This operator performs an affine transform on an image using @interpolate.
  *
@@ -633,6 +675,8 @@ vips_affine_init( VipsAffine *affine )
  * By default @oarea is just large enough to cover the whole of the 
  * transformed input image.
  *
+ * New pixels are filled with @background. This defaults to zero (black). 
+ *
  * @interpolate defaults to bilinear. 
  *
  * @idx, @idy, @odx, @ody default to zero.

libvips/resample/similarity.c

@@ -10,6 +10,9 @@
  * 	- oops, missing scale from b, thanks Topochicho
  * 7/2/16
  * 	- use vips_reduce(), if we can
+ * 17/11/17
+ * `	- add optional "background" param
+ * `	- don't use vips_reduce() since it has no "background" param
  */
 
 /*
@@ -65,6 +68,7 @@ typedef struct _VipsSimilarity {
 	double ody;
 	double idx;
 	double idy;
+	VipsArrayDouble *background;
 
 } VipsSimilarity;
 
@@ -72,19 +76,6 @@ typedef VipsResampleClass VipsSimilarityClass;
 
 G_DEFINE_TYPE( VipsSimilarity, vips_similarity, VIPS_TYPE_RESAMPLE );
 
-/* Map interpolator names to vips kernels.
- */
-typedef struct _VipsInterpolateKernel {
-	const char *nickname;
-	VipsKernel kernel;
-} VipsInterpolateKernel;
-
-static VipsInterpolateKernel vips_similarity_kernel[] = {
-	{ "bicubic", VIPS_KERNEL_CUBIC },
-	{ "bilinear", VIPS_KERNEL_LINEAR },
-	{ "nearest", VIPS_KERNEL_NEAREST }
-}; 
-
 static int
 vips_similarity_build( VipsObject *object )
 {
@@ -92,61 +83,23 @@ vips_similarity_build( VipsObject *object )
 	VipsSimilarity *similarity = (VipsSimilarity *) object;
 	VipsImage **t = (VipsImage **) 
 		vips_object_local_array( object, 4 );
-
+	double a = similarity->scale * cos( VIPS_RAD( similarity->angle ) ); 
-	gboolean handled;
+	double b = similarity->scale * -sin( VIPS_RAD( similarity->angle ) );
+	double c = -b;
+	double d = a;
 
 	if( VIPS_OBJECT_CLASS( vips_similarity_parent_class )->build( object ) )
 		return( -1 );
 
-	handled = FALSE;
+	if( vips_affine( resample->in, &t[0], a, b, c, d, 
-
+		"interpolate", similarity->interpolate,
-	/* Use vips_reduce(), if we can.
+		"odx", similarity->odx,
-	 */
+		"ody", similarity->ody,
-	if( similarity->interpolate &&
+		"idx", similarity->idx,
-		similarity->angle == 0.0 &&
+		"idy", similarity->idy,
-		similarity->idx == 0.0 &&
+		"background", similarity->background,
-		similarity->idy == 0.0 &&
+		NULL ) )
-		similarity->odx == 0.0 &&
+		return( -1 );
-		similarity->ody == 0.0 ) {
-		const char *nickname = VIPS_OBJECT_GET_CLASS( 
-			similarity->interpolate )->nickname;
-
-		int i; 
-
-		for( i = 0; i < VIPS_NUMBER( vips_similarity_kernel ); i++ ) {
-			VipsInterpolateKernel *ik = &vips_similarity_kernel[i];
-
-			if( strcmp( nickname, ik->nickname ) == 0 ) {
-				if( vips_reduce( resample->in, &t[0], 
-					1.0 / similarity->scale, 
-					1.0 / similarity->scale, 
-					"kernel", ik->kernel,
-					NULL ) )
-					return( -1 );
-
-				handled = TRUE;
-				break;
-			}
-		}
-	}
-
-	if( !handled ) { 
-		double a = similarity->scale * 
-			cos( VIPS_RAD( similarity->angle ) ); 
-		double b = similarity->scale * 
-			-sin( VIPS_RAD( similarity->angle ) );
-		double c = -b;
-		double d = a;
-
-		if( vips_affine( resample->in, &t[0], a, b, c, d, 
-			"interpolate", similarity->interpolate,
-			"odx", similarity->odx,
-			"ody", similarity->ody,
-			"idx", similarity->idx,
-			"idy", similarity->idy,
-			NULL ) )
-			return( -1 );
-	}
 
 	if( vips_image_write( t[0], resample->out ) )
 		return( -1 ); 
@@ -214,6 +167,13 @@ vips_similarity_class_init( VipsSimilarityClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsSimilarity, idy ),
 		-10000000, 10000000, 0 );
+
+	VIPS_ARG_BOXED( class, "background", 2, 
+		_( "Background" ), 
+		_( "Background value" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsSimilarity, background ),
+		VIPS_TYPE_ARRAY_DOUBLE );
 }
 
 static void
@@ -226,6 +186,7 @@ vips_similarity_init( VipsSimilarity *similarity )
 	similarity->ody = 0; 
 	similarity->idx = 0; 
 	similarity->idy = 0; 
+	similarity->background = vips_array_double_newv( 1, 0.0 );
 }
 
 /**
@@ -243,6 +204,8 @@ vips_similarity_init( VipsSimilarity *similarity )
  * * @idy: %gdouble, input vertical offset
  * * @odx: %gdouble, output horizontal offset
  * * @ody: %gdouble, output vertical offset
+ * * @ody: %gdouble, output vertical offset
+ * * @background: #VipsArrayDouble colour for new pixels 
  *
  * This operator calls vips_affine() for you, calculating the matrix for the
  * affine transform from @scale and @angle. Other parameters are passed on to