Merge pull request #915 from harukizaemon/region-shrink-method

WIP: Adds a region shrink method

libvips/foreign/dzsave.c

@@ -447,6 +447,7 @@ struct _VipsForeignSaveDz {
 	VipsAngle angle;
 	VipsForeignDzContainer container; 
 	int compression;
+	VipsRegionShrink region_shrink;
 
 	/* Tile and overlap geometry. The members above are the parameters we
 	 * accept, this next set are the derived values which are actually 
@@ -1355,6 +1356,8 @@ strip_shrink( Layer *layer )
 	Layer *below = layer->below;
 	VipsRegion *from = layer->strip;
 	VipsRegion *to = below->strip;
+	VipsForeignSaveDz *dz = layer->dz;
+	VipsRegionShrink region_shrink = dz->region_shrink;
 
 	VipsRect target;
 	VipsRect source;
@@ -1401,10 +1404,11 @@ strip_shrink( Layer *layer )
 
 		/* None? All done.
 		 */
-		if( vips_rect_isempty( &target ) ) 
+		if( vips_rect_isempty( &target ) )
 			break;
 
-		(void) vips_region_shrink( from, to, &target );
+		(void) vips_region_shrink( from, to, &target,
+			region_shrink );
 
 		below->write_y += target.height;
 
@@ -2098,6 +2102,14 @@ vips_foreign_save_dz_class_init( VipsForeignSaveDzClass *class )
 		G_STRUCT_OFFSET( VipsForeignSaveDz, compression ),
 		-1, 9, 0 );
 
+	VIPS_ARG_ENUM( class, "region_shrink", 18, 
+		_( "Region shrink" ), 
+		_( "Method for blah" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignSaveDz, region_shrink ),
+		VIPS_TYPE_REGION_SHRINK, 
+			VIPS_REGION_SHRINK_MEAN ); 
+
 	/* How annoying. We stupidly had these in earlier versions.
 	 */
 
@@ -2136,6 +2148,7 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
 	dz->angle = VIPS_ANGLE_D0; 
 	dz->container = VIPS_FOREIGN_DZ_CONTAINER_FS; 
 	dz->compression = 0;
+	dz->region_shrink = VIPS_REGION_SHRINK_MEAN;
 }
 
 typedef struct _VipsForeignSaveDzFile {
@@ -2332,6 +2345,7 @@ vips_foreign_save_dz_buffer_init( VipsForeignSaveDzBuffer *buffer )
  * * @container: #VipsForeignDzContainer set container type
  * * @properties: %gboolean write a properties file
  * * @compression: %gint zip deflate compression level
+ * * @shrink_region: #VipsRegionShrink How to shrink each 2x2 region.
  *
  * Save an image as a set of tiles at various resolutions. By default dzsave
  * uses DeepZoom layout -- use @layout to pick other conventions.
@@ -2375,6 +2389,10 @@ vips_foreign_save_dz_buffer_init( VipsForeignSaveDzBuffer *buffer )
  * (use zlib default), 0 (store, compression disabled) to 9 (max compression).
  * If no value is given, the default is to store files without compression.
  *
+ * You can use @region_shrink to control the method for shrinking each 2x2
+ * region. This defaults to using the average of the 4 input pixels but you can
+ * also use the median in cases where you want to preseve the range of values.
+ * 
  * See also: vips_tiffsave().
  *
  * Returns: 0 on success, -1 on error.

libvips/foreign/vips2tiff.c

@@ -1389,10 +1389,11 @@ layer_strip_shrink( Layer *layer )
 
 		/* None? All done.
 		 */
-		if( vips_rect_isempty( &target ) ) 
+		if( vips_rect_isempty( &target ) )
 			break;
 
-		(void) vips_region_shrink( from, to, &target );
+		(void) vips_region_shrink( from, to, &target,
+			VIPS_REGION_SHRINK_MEAN );
 
 		below->write_y += target.height;
 

libvips/include/vips/Makefile.am

@@ -72,7 +72,8 @@ vips_scan_headers = \
 	${top_srcdir}/libvips/include/vips/morphology.h \
 	${top_srcdir}/libvips/include/vips/draw.h \
 	${top_srcdir}/libvips/include/vips/basic.h \
-	${top_srcdir}/libvips/include/vips/object.h
+	${top_srcdir}/libvips/include/vips/object.h \
+	${top_srcdir}/libvips/include/vips/region.h
 
 enumtypes.h: $(vips_scan_headers) Makefile.am
 	glib-mkenums --template enumtemplate $(vips_scan_headers) > enumtypes.h

libvips/include/vips/region.h

@@ -55,6 +55,21 @@ extern "C" {
 	(G_TYPE_INSTANCE_GET_CLASS( (obj), \
 	VIPS_TYPE_REGION, VipsRegionClass ))
 
+/**
+ * VipsRegionShrink:
+ * @VIPS_REGION_SHRINK_MEAN: use the average
+ * @VIPS_REGION_SHRINK_MEDIAN: use the median
+ * @VIPS_REGION_SHRINK_MODE: use the mode
+ *
+ * How to calculate the output pixels when shrinking a 2x2 region.
+ */
+typedef enum {
+	VIPS_REGION_SHRINK_MEAN,
+	VIPS_REGION_SHRINK_MEDIAN,
+	VIPS_REGION_SHRINK_MODE,
+	VIPS_REGION_SHRINK_LAST
+} VipsRegionShrink;
+
 /* Sub-area of image.
  */
 typedef struct _VipsRegion {
@@ -115,13 +130,14 @@ void vips_region_paint( VipsRegion *reg, const VipsRect *r, int value );
 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, 
+void vips_region_copy( VipsRegion *reg, VipsRegion *dest,
 	const VipsRect *r, int x, int y );
-int vips_region_shrink( VipsRegion *from, 
+int vips_region_shrink( VipsRegion *from,
-	VipsRegion *to, const VipsRect *target );
+	VipsRegion *to, const VipsRect *target,
+	VipsRegionShrink method );
 
 int vips_region_prepare( VipsRegion *reg, const VipsRect *r );
-int vips_region_prepare_to( VipsRegion *reg, 
+int vips_region_prepare_to( VipsRegion *reg,
 	VipsRegion *dest, const VipsRect *r, int x, int y );
 
 void vips_region_invalidate( VipsRegion *reg );

libvips/iofuncs/Makefile.am

@@ -70,7 +70,8 @@ vips_scan_headers = \
 	${top_srcdir}/libvips/include/vips/morphology.h \
 	${top_srcdir}/libvips/include/vips/draw.h \
 	${top_srcdir}/libvips/include/vips/basic.h \
-	${top_srcdir}/libvips/include/vips/object.h
+	${top_srcdir}/libvips/include/vips/object.h \
+	${top_srcdir}/libvips/include/vips/region.h
 
 enumtypes.c: $(vips_scan_headers) Makefile.am
 	glib-mkenums --template enumtemplate $(vips_scan_headers) > enumtypes.c

libvips/iofuncs/enumtypes.c

@@ -866,6 +866,26 @@ vips_operation_flags_get_type( void )
 
 	return( etype );
 }
+/* enumerations from "../../libvips/include/vips/region.h" */
+GType
+vips_region_shrink_get_type( void )
+{
+	static GType etype = 0;
+
+	if( etype == 0 ) {
+		static const GEnumValue values[] = {
+			{VIPS_REGION_SHRINK_MEAN, "VIPS_REGION_SHRINK_MEAN", "mean"},
+			{VIPS_REGION_SHRINK_MEDIAN, "VIPS_REGION_SHRINK_MEDIAN", "median"},
+			{VIPS_REGION_SHRINK_MODE, "VIPS_REGION_SHRINK_MODE", "mode"},
+			{VIPS_REGION_SHRINK_LAST, "VIPS_REGION_SHRINK_LAST", "last"},
+			{0, NULL, NULL}
+		};
+		
+		etype = g_enum_register_static( "VipsRegionShrink", values );
+	}
+
+	return( etype );
+}
 /* enumerations from "../../libvips/include/vips/resample.h" */
 GType
 vips_kernel_get_type( void )

libvips/iofuncs/region.c

@@ -1166,7 +1166,7 @@ vips_region_shrink_labpack( VipsRegion *from,
 	}
 }
 
-#define SHRINK_TYPE_INT( TYPE ) \
+#define SHRINK_TYPE_MEAN_INT( TYPE ) \
 	for( x = 0; x < target->width; x++ ) { \
 		TYPE *tp = (TYPE *) p; \
 		TYPE *tp1 = (TYPE *) (p + ls); \
@@ -1185,7 +1185,7 @@ vips_region_shrink_labpack( VipsRegion *from,
 		q += ps; \
 	}
 
-#define SHRINK_TYPE_FLOAT( TYPE )  \
+#define SHRINK_TYPE_MEAN_FLOAT( TYPE )  \
 	for( x = 0; x < target->width; x++ ) { \
 		TYPE *tp = (TYPE *) p; \
 		TYPE *tp1 = (TYPE *) (p + ls); \
@@ -1204,10 +1204,69 @@ vips_region_shrink_labpack( VipsRegion *from,
 		q += ps; \
 	}
 
+/* This method is implemented so as to perform well and to always select an
+ * output pixel from one of the input pixels. As such we make only the
+ * following guarantees:
+ *
+ * ONLY works for non-complex uncoded images pixel types
+ * ALWAYS draws from the input values
+ * NEVER interpolates
+ * NOT stable with respect to the ordered set of input values
+ * IS stable with respect to the initial arrangement of input values
+ */
+#define SHRINK_TYPE_MEDIAN( TYPE ) \
+	for( x = 0; x < target->width; x++ ) { \
+		TYPE *tp = (TYPE *) p; \
+		TYPE *tp1 = (TYPE *) (p + ls); \
+		TYPE *tq = (TYPE *) q; \
+		\
+		for( z = 0; z < nb; z++ ) { \
+        		tq[z] = VIPS_MIN( \
+					VIPS_MAX( tp[z], tp[z + nb] ), \
+					VIPS_MAX( tp1[z], tp1[z + nb] ) \
+				); \
+		} \
+		\
+		/* Move on two pels in input. \
+		 */ \
+		p += ps << 1; \
+		q += ps; \
+	}
+
+/* This method is implemented so as to perform well and to always select an
+ * output pixel from one of the input pixels. As such we make only the
+ * following guarantees:
+ *
+ * ONLY works for non-complex uncoded images pixel types
+ * ALWAYS draws from the input values
+ * NEVER interpolates
+ * NOT stable with respect to the ordered set of input values
+ * IS stable with respect to the initial arrangement of input values
+ */
+#define SHRINK_TYPE_MODE( TYPE ) \
+	for( x = 0; x < target->width; x++ ) { \
+		TYPE *tp = (TYPE *) p; \
+		TYPE *tp1 = (TYPE *) (p + ls); \
+		TYPE *tq = (TYPE *) q; \
+		\
+		for( z = 0; z < nb; z++ ) { \
+			TYPE v[] = {tp[z], tp[z + nb], tp1[z], tp1[z + nb]}; \
+		    	int b0 = (v[0] == v[1]) | (v[0] == v[2]) | (v[0] == v[3]); \
+    			int b1 = (v[1] == v[0]) | (v[1] == v[2]) | (v[1] == v[3]); \
+    			int index = ((~b0) & 0x1) + (~(b0 ^ b1) & 0x1); \
+        		tq[z] = v[index]; \
+		} \
+		\
+		/* Move on two pels in input. \
+		 */ \
+		p += ps << 1; \
+		q += ps; \
+	}
+
 /* Generate area @target in @to using pixels in @from. Non-complex.
  */
 static void
-vips_region_shrink_uncoded( VipsRegion *from, 
+vips_region_shrink_uncoded_mean( VipsRegion *from,
 	VipsRegion *to, const VipsRect *target )
 {
 	int ls = VIPS_REGION_LSKIP( from );
@@ -1225,22 +1284,22 @@ vips_region_shrink_uncoded( VipsRegion *from,
 		/* Process this line of pels.
 		 */
 		switch( from->im->BandFmt ) {
-		case VIPS_FORMAT_UCHAR:	
+		case VIPS_FORMAT_UCHAR:
-			SHRINK_TYPE_INT( unsigned char );  break; 
+			SHRINK_TYPE_MEAN_INT( unsigned char );  break;
-		case VIPS_FORMAT_CHAR:	
+		case VIPS_FORMAT_CHAR:
-			SHRINK_TYPE_INT( signed char );  break; 
+			SHRINK_TYPE_MEAN_INT( signed char );  break;
-		case VIPS_FORMAT_USHORT:	
+		case VIPS_FORMAT_USHORT:
-			SHRINK_TYPE_INT( unsigned short );  break; 
+			SHRINK_TYPE_MEAN_INT( unsigned short );  break;
-		case VIPS_FORMAT_SHORT:	
+		case VIPS_FORMAT_SHORT:
-			SHRINK_TYPE_INT( signed short );  break; 
+			SHRINK_TYPE_MEAN_INT( signed short );  break;
-		case VIPS_FORMAT_UINT:	
+		case VIPS_FORMAT_UINT:
-			SHRINK_TYPE_INT( unsigned int );  break; 
+			SHRINK_TYPE_MEAN_INT( unsigned int );  break;
-		case VIPS_FORMAT_INT:	
+		case VIPS_FORMAT_INT:
-			SHRINK_TYPE_INT( signed int );  break; 
+			SHRINK_TYPE_MEAN_INT( signed int );  break;
-		case VIPS_FORMAT_FLOAT:	
+		case VIPS_FORMAT_FLOAT:
-			SHRINK_TYPE_FLOAT( float );  break; 
+			SHRINK_TYPE_MEAN_FLOAT( float );  break;
-		case VIPS_FORMAT_DOUBLE:	
+		case VIPS_FORMAT_DOUBLE:
-			SHRINK_TYPE_FLOAT( double );  break; 
+			SHRINK_TYPE_MEAN_FLOAT( double );  break;
 
 		default:
 			g_assert_not_reached();
@@ -1248,6 +1307,116 @@ vips_region_shrink_uncoded( VipsRegion *from,
 	}
 }
 
+/* Generate area @target in @to using pixels in @from. Non-complex.
+ */
+static void
+vips_region_shrink_uncoded_median( VipsRegion *from,
+	VipsRegion *to, const VipsRect *target )
+{
+	int ls = VIPS_REGION_LSKIP( from );
+	int ps = VIPS_IMAGE_SIZEOF_PEL( from->im );
+	int nb = from->im->Bands;
+
+	int x, y, z;
+
+	for( y = 0; y < target->height; y++ ) {
+		VipsPel *p = VIPS_REGION_ADDR( from,
+			target->left * 2, (target->top + y) * 2 );
+		VipsPel *q = VIPS_REGION_ADDR( to,
+			target->left, target->top + y );
+
+		/* Process this line of pels.
+		 */
+		switch( from->im->BandFmt ) {
+		case VIPS_FORMAT_UCHAR:
+			SHRINK_TYPE_MEDIAN( unsigned char );  break;
+		case VIPS_FORMAT_CHAR:
+			SHRINK_TYPE_MEDIAN( signed char );  break;
+		case VIPS_FORMAT_USHORT:
+			SHRINK_TYPE_MEDIAN( unsigned short );  break;
+		case VIPS_FORMAT_SHORT:
+			SHRINK_TYPE_MEDIAN( signed short );  break;
+		case VIPS_FORMAT_UINT:
+			SHRINK_TYPE_MEDIAN( unsigned int );  break;
+		case VIPS_FORMAT_INT:
+			SHRINK_TYPE_MEDIAN( signed int );  break;
+		case VIPS_FORMAT_FLOAT:
+			SHRINK_TYPE_MEDIAN( float );  break;
+		case VIPS_FORMAT_DOUBLE:
+			SHRINK_TYPE_MEDIAN( double );  break;
+
+		default:
+			g_assert_not_reached();
+		}
+	}
+}
+
+/* Generate area @target in @to using pixels in @from. Non-complex.
+ */
+static void
+vips_region_shrink_uncoded_mode( VipsRegion *from,
+	VipsRegion *to, const VipsRect *target )
+{
+	int ls = VIPS_REGION_LSKIP( from );
+	int ps = VIPS_IMAGE_SIZEOF_PEL( from->im );
+	int nb = from->im->Bands;
+
+	int x, y, z;
+
+	for( y = 0; y < target->height; y++ ) {
+		VipsPel *p = VIPS_REGION_ADDR( from,
+			target->left * 2, (target->top + y) * 2 );
+		VipsPel *q = VIPS_REGION_ADDR( to,
+			target->left, target->top + y );
+
+		/* Process this line of pels.
+		 */
+		switch( from->im->BandFmt ) {
+		case VIPS_FORMAT_UCHAR:
+			SHRINK_TYPE_MODE( unsigned char );  break;
+		case VIPS_FORMAT_CHAR:
+			SHRINK_TYPE_MODE( signed char );  break;
+		case VIPS_FORMAT_USHORT:
+			SHRINK_TYPE_MODE( unsigned short );  break;
+		case VIPS_FORMAT_SHORT:
+			SHRINK_TYPE_MODE( signed short );  break;
+		case VIPS_FORMAT_UINT:
+			SHRINK_TYPE_MODE( unsigned int );  break;
+		case VIPS_FORMAT_INT:
+			SHRINK_TYPE_MODE( signed int );  break;
+		case VIPS_FORMAT_FLOAT:
+			SHRINK_TYPE_MODE( float );  break;
+		case VIPS_FORMAT_DOUBLE:
+			SHRINK_TYPE_MODE( double );  break;
+
+		default:
+			g_assert_not_reached();
+		}
+	}
+}
+
+/* Generate area @target in @to using pixels in @from. Non-complex.
+ */
+static void
+vips_region_shrink_uncoded( VipsRegion *from,
+	VipsRegion *to, const VipsRect *target, VipsRegionShrink method )
+{
+	switch( method ) {
+		case VIPS_REGION_SHRINK_MEAN:
+			vips_region_shrink_uncoded_mean( from, to, target );
+			break;
+		case VIPS_REGION_SHRINK_MEDIAN:
+			vips_region_shrink_uncoded_median( from, to, target );
+			break;
+		case VIPS_REGION_SHRINK_MODE:
+			vips_region_shrink_uncoded_mode( from, to, target );
+			break;
+
+		default:
+			g_assert_not_reached();
+	}
+}
+
 /* No point having an int path, this will always be horribly slow.
  */
 #define SHRINK_ALPHA_TYPE( TYPE ) { \
@@ -1333,9 +1502,10 @@ vips_region_shrink_alpha( VipsRegion *from,
 
 /**
  * vips_region_shrink:
- * @from: source region 
+ * @from: source region
- * @to: (inout): destination region 
+ * @to: (inout): destination region
  * @target: #VipsRect of pixels you need to copy
+ * @method: #VipsRegionShrink method to use when generating target pixels
  *
  * Write the pixels @target in @to from the x2 larger area in @from.
  * Non-complex uncoded images and LABQ only. Images with alpha (see
@@ -1344,7 +1514,8 @@ vips_region_shrink_alpha( VipsRegion *from,
  * See also: vips_region_copy().
  */
 int
-vips_region_shrink( VipsRegion *from, VipsRegion *to, const VipsRect *target )
+vips_region_shrink( VipsRegion *from, VipsRegion *to, const VipsRect *target,
+	VipsRegionShrink method )
 {
 	VipsImage *image = from->im;
 
@@ -1355,10 +1526,10 @@ vips_region_shrink( VipsRegion *from, VipsRegion *to, const VipsRect *target )
 		if( vips_check_noncomplex(  "vips_region_shrink", image ) )
 			return( -1 );
 
-		if( vips_image_hasalpha( image ) ) 
+		if( vips_image_hasalpha( image ) )
 			vips_region_shrink_alpha( from, to, target );
 		else
-			vips_region_shrink_uncoded( from, to, target );
+			vips_region_shrink_uncoded( from, to, target, method );
 	}
 	else
 		vips_region_shrink_labpack( from, to, target );