add vips_flatten()

... background arg not quite working

ChangeLog

@@ -1,3 +1,8 @@
+18/6/12 started 7.28.7
+- add vips_flatten() -- flatten RGBA to RGB
+- better alpha handling in PNG load
+- don't save RGBA PNG as CMYK JPG
+
 19/4/12 started 7.28.6
 - better resolution unit handling in deprecated im_vips2tiff()
 - use TIFF_CFLAGS output from pkg-config (thanks Jay)

TODO

@@ -1,6 +1,17 @@
 - on RGBA -> RGB conversion in foreign.c, need to use A channel to mask off
   RGB ... Opera.png looks bad without it
 
+- vipsthumbnail.c could use this instead of im_tile_cache() to get seq hint
+  set
+
+	if( vips_tilecache( in, out, 
+		"tile_width", in->Xsize, 
+		"tile_height", strip_height * nstrips,
+		"max_tiles", 2,
+		"strategy", VIPS_CACHE_SEQUENTIAL,
+		NULL ) )
+		return( -1 );
+
 
 
 

configure.in

@@ -15,7 +15,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # user-visible library versioning
 m4_define([vips_major_version], [7])
 m4_define([vips_minor_version], [28])
-m4_define([vips_micro_version], [6])
+m4_define([vips_micro_version], [7])
 m4_define([vips_version],
           [vips_major_version.vips_minor_version.vips_micro_version])
 
@@ -34,9 +34,9 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date`
 #   interface changes backwards compatible?: increment age
 #   interface changes not backwards compatible?: reset age to 0
 
-LIBRARY_CURRENT=32
+LIBRARY_CURRENT=33
 LIBRARY_REVISION=0
-LIBRARY_AGE=0
+LIBRARY_AGE=1
 
 # patched into include/vips/version.h
 AC_SUBST(VIPS_VERSION)

libvips/conversion/Makefile.am

@@ -5,6 +5,7 @@ libconversion_la_SOURCES = \
 	conversion.h \
 	tilecache.c \
 	sequential.c \
+	flatten.c \
 	cache.c \
 	copy.c \
 	embed.c \

libvips/conversion/conversion.c

@@ -121,6 +121,7 @@ vips_conversion_operation_init( void )
 	extern GType vips_ifthenelse_get_type( void ); 
 	extern GType vips_recomb_get_type( void ); 
 	extern GType vips_bandmean_get_type( void ); 
+	extern GType vips_flatten_get_type( void ); 
 
 	vips_copy_get_type();
 	vips_tile_cache_get_type(); 
@@ -140,6 +141,7 @@ vips_conversion_operation_init( void )
 	vips_ifthenelse_get_type();
 	vips_recomb_get_type(); 
 	vips_bandmean_get_type(); 
+	vips_flatten_get_type(); 
 }
 
 /* The common part of most binary conversion

libvips/conversion/flatten.c

@@ -0,0 +1,428 @@
+/* flatten the alpha out of an image, replacing it with a constant background
+ *
+ * Author: John Cupitt
+ * Written on: 18/6/12
+ */
+
+/*
+
+    This file is part of VIPS.
+    
+    VIPS is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+/*
+#define VIPS_DEBUG
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include <vips/vips.h>
+#include <vips/internal.h>
+#include <vips/debug.h>
+
+#include "conversion.h"
+
+typedef struct _VipsFlatten {
+	VipsConversion parent_instance;
+
+	VipsImage *in;
+
+	/* Background colour.
+	 */
+	VipsArea *background;
+
+	/* The [double] converted to the input image format.
+	 */
+	VipsPel *ink;
+
+} VipsFlatten;
+
+typedef VipsConversionClass VipsFlattenClass;
+
+G_DEFINE_TYPE( VipsFlatten, vips_flatten, VIPS_TYPE_CONVERSION );
+
+/* Shift A down N places, rounding to nearest.
+ *
+ * This calculates A / B, rounding the result to nearest, ie.
+ *
+ * 	(a + (b / 2)) / b
+ *
+ * We mustn't overflow during the add, so we actually do:
+ *
+ * 	((a / 2) + (b / 4)) / (b / 2)
+ *
+ * slightly less accurate, but safe from overflow.
+ */
+#define SHIFT_ROUND( A, N ) \
+	((((A) >> 1) + (1 << ((N) - 2)) - 1) >> ((N) - 1))
+
+/* Flatten with shift + round, black background.
+ */
+#define VIPS_FLATTEN_INT_BLACK( TYPE, N ) { \
+	TYPE *p = (TYPE *) in; \
+	TYPE *q = (TYPE *) out; \
+	\
+	for( x = 0; x < width; x++ ) { \
+		TYPE alpha = p[bands - 1]; \
+		int b; \
+		\
+		for( b = 0; b < bands - 1; b++ ) \
+			q[b] = SHIFT_ROUND( p[b] * alpha, N ); \
+		\
+		p += bands; \
+		q += bands - 1; \
+	} \
+}
+
+/* Flatten with shift + round, any background.
+ */
+#define VIPS_FLATTEN_INT( TYPE, N ) { \
+	TYPE *p = (TYPE *) in; \
+	TYPE *q = (TYPE *) out; \
+	\
+	for( x = 0; x < width; x++ ) { \
+		TYPE alpha = p[bands - 1]; \
+		TYPE nalpha = ((1 << (N)) - 1) - alpha; \
+		TYPE *bg = (TYPE *) flatten->ink; \
+		int b; \
+		\
+		for( b = 0; b < bands - 1; b++ ) \
+			q[b] = SHIFT_ROUND( p[b] * alpha, (N) ) + \
+				SHIFT_ROUND( bg[b] * nalpha, (N) ); \
+		\
+		p += bands; \
+		q += bands - 1; \
+	} \
+}
+
+/* Flatten via float division, black background. 
+ */
+#define VIPS_FLATTEN_FLOAT_BLACK( TYPE, SCALE ) { \
+	TYPE *p = (TYPE *) in; \
+	TYPE *q = (TYPE *) out; \
+	\
+	for( x = 0; x < width; x++ ) { \
+		TYPE alpha = p[bands - 1]; \
+		int b; \
+		\
+		for( b = 0; b < bands - 1; b++ ) \
+			q[b] = ((double) p[b] * alpha) / (SCALE); \
+		\
+		p += bands; \
+		q += bands - 1; \
+	} \
+}
+
+/* Flatten via float division, any background. 
+ */
+#define VIPS_FLATTEN_FLOAT( TYPE, SCALE ) { \
+	TYPE *p = (TYPE *) in; \
+	TYPE *q = (TYPE *) out; \
+	\
+	for( x = 0; x < width; x++ ) { \
+		TYPE alpha = p[bands - 1]; \
+		TYPE nalpha = (SCALE) - alpha; \
+		TYPE *bg = (TYPE *) flatten->ink; \
+		int b; \
+		\
+		for( b = 0; b < bands - 1; b++ ) \
+			q[b] = ((double) p[b] * alpha) / (SCALE) + \
+				((double) bg[b] * nalpha) / (SCALE); \
+		\
+		p += bands; \
+		q += bands - 1; \
+	} \
+}
+
+static int
+vips_flatten_black_gen( VipsRegion *or, void *vseq, void *a, void *b,
+	gboolean *stop )
+{
+	VipsRegion *ir = (VipsRegion *) vseq;
+	VipsFlatten *flatten = (VipsFlatten *) b;
+	VipsRect *r = &or->valid;
+	int width = r->width;
+	int bands = ir->im->Bands; 
+
+	int x, y;
+
+	if( vips_region_prepare( ir, r ) )
+		return( -1 );
+
+	for( y = 0; y < r->height; y++ ) {
+		VipsPel *in = VIPS_REGION_ADDR( ir, r->left, r->top + y ); 
+		VipsPel *out = VIPS_REGION_ADDR( or, r->left, r->top + y ); 
+
+		switch( flatten->in->BandFmt ) { 
+		case VIPS_FORMAT_UCHAR: 
+			VIPS_FLATTEN_INT_BLACK( unsigned char, 8 ); 
+			break; 
+
+		case VIPS_FORMAT_CHAR: 
+			/* Alpha is 0 - 127? No idea, really.
+			 */
+			VIPS_FLATTEN_INT_BLACK( signed char, 7 ); 
+			break; 
+
+		case VIPS_FORMAT_USHORT: 
+			VIPS_FLATTEN_INT_BLACK( unsigned short, 16 ); 
+			break; 
+
+		case VIPS_FORMAT_SHORT: 
+			VIPS_FLATTEN_INT_BLACK( signed short, 15 ); 
+			break; 
+
+		case VIPS_FORMAT_UINT: 
+			VIPS_FLATTEN_FLOAT_BLACK( unsigned int, UINT_MAX ); 
+			break; 
+
+		case VIPS_FORMAT_INT: 
+			VIPS_FLATTEN_FLOAT_BLACK( signed int, INT_MAX ); 
+			break; 
+
+		case VIPS_FORMAT_FLOAT: 
+			VIPS_FLATTEN_FLOAT_BLACK( float, 1.0 ); 
+			break; 
+
+		case VIPS_FORMAT_DOUBLE: 
+			VIPS_FLATTEN_FLOAT_BLACK( double, 1.0 ); 
+			break; 
+
+		case VIPS_FORMAT_COMPLEX: 
+		case VIPS_FORMAT_DPCOMPLEX: 
+		default: 
+			g_assert( 0 ); 
+		} 
+	}
+
+	return( 0 );
+}
+
+/* Any background.
+ */
+static int
+vips_flatten_gen( VipsRegion *or, void *vseq, void *a, void *b,
+	gboolean *stop )
+{
+	VipsRegion *ir = (VipsRegion *) vseq;
+	VipsFlatten *flatten = (VipsFlatten *) b;
+	VipsRect *r = &or->valid;
+	int width = r->width;
+	int bands = ir->im->Bands; 
+
+	int x, y;
+
+	if( vips_region_prepare( ir, r ) )
+		return( -1 );
+
+	for( y = 0; y < r->height; y++ ) {
+		VipsPel *in = VIPS_REGION_ADDR( ir, r->left, r->top + y ); 
+		VipsPel *out = VIPS_REGION_ADDR( or, r->left, r->top + y ); 
+
+		switch( flatten->in->BandFmt ) { 
+		case VIPS_FORMAT_UCHAR: 
+			VIPS_FLATTEN_INT( unsigned char, 8 ); 
+			break; 
+
+		case VIPS_FORMAT_CHAR: 
+			/* Alpha is 0 - 127? No idea, really.
+			 */
+			VIPS_FLATTEN_INT( signed char, 7 ); 
+			break; 
+
+		case VIPS_FORMAT_USHORT: 
+			VIPS_FLATTEN_INT( unsigned short, 16 ); 
+			break; 
+
+		case VIPS_FORMAT_SHORT: 
+			VIPS_FLATTEN_INT( signed short, 15 ); 
+			break; 
+
+		case VIPS_FORMAT_UINT: 
+			VIPS_FLATTEN_FLOAT( unsigned int, UINT_MAX ); 
+			break; 
+
+		case VIPS_FORMAT_INT: 
+			VIPS_FLATTEN_FLOAT( signed int, INT_MAX ); 
+			break; 
+
+		case VIPS_FORMAT_FLOAT: 
+			VIPS_FLATTEN_FLOAT( float, 1.0 ); 
+			break; 
+
+		case VIPS_FORMAT_DOUBLE: 
+			VIPS_FLATTEN_FLOAT( double, 1.0 ); 
+			break; 
+
+		case VIPS_FORMAT_COMPLEX: 
+		case VIPS_FORMAT_DPCOMPLEX: 
+		default: 
+			g_assert( 0 ); 
+		} 
+	}
+
+	return( 0 );
+}
+
+
+static int
+vips_flatten_build( VipsObject *object )
+{
+	VipsConversion *conversion = VIPS_CONVERSION( object );
+	VipsFlatten *flatten = (VipsFlatten *) object;
+	int i;
+	gboolean black;
+
+	if( VIPS_OBJECT_CLASS( vips_flatten_parent_class )->build( object ) )
+		return( -1 );
+
+	/* Trivial case: fall back to copy().
+	 */
+	if( flatten->in->Bands == 1 ) 
+		return( vips_image_write( flatten->in, conversion->out ) );
+
+	if( vips_check_uncoded( "VipsFlatten", flatten->in ) ||
+		vips_check_noncomplex( "VipsFlatten", flatten->in ) ||
+		vips_image_pio_input( flatten->in ) )
+		return( -1 );
+
+	if( vips_image_copy_fields( conversion->out, flatten->in ) )
+		return( -1 );
+	vips_demand_hint( conversion->out, 
+		VIPS_DEMAND_STYLE_THINSTRIP, flatten->in, NULL );
+
+	conversion->out->Bands -= 1;
+
+	/* Is the background black? We have a special path for this.
+	 */
+	black = TRUE;
+	for( i = 0; i < flatten->background->n; i++ )
+		if( ((double *) flatten->background->data)[i] != 0.0 ) {
+			black = FALSE;
+			break;
+		}
+
+	if( black ) {
+		if( vips_image_generate( conversion->out,
+			vips_start_one, vips_flatten_black_gen, vips_stop_one, 
+			flatten->in, flatten ) )
+			return( -1 );
+	}
+	else {
+		/* Convert the background to the image's format.
+		 */
+		if( !(flatten->ink = vips__vector_to_ink( 
+			"VipsFlatten", conversion->out,
+			flatten->background->data, flatten->background->n )) )
+			return( -1 );
+
+		if( vips_image_generate( conversion->out,
+			vips_start_one, vips_flatten_gen, vips_stop_one, 
+			flatten->in, flatten ) )
+			return( -1 );
+	}
+
+	return( 0 );
+}
+
+static void
+vips_flatten_class_init( VipsFlattenClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
+
+	VIPS_DEBUG_MSG( "vips_flatten_class_init\n" );
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	vobject_class->nickname = "flatten";
+	vobject_class->description = _( "flatten alpha out of an image" );
+	vobject_class->build = vips_flatten_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsFlatten, in ) );
+
+	VIPS_ARG_BOXED( class, "background", 2, 
+		_( "Background" ), 
+		_( "Background value" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsFlatten, background ),
+		VIPS_TYPE_ARRAY_DOUBLE );
+}
+
+static void
+vips_flatten_init( VipsFlatten *flatten )
+{
+	flatten->background = 
+		vips_area_new_array( G_TYPE_DOUBLE, sizeof( double ), 1 ); 
+	((double *) (flatten->background->data))[0] = 0.0;
+}
+
+/**
+ * vips_flatten:
+ * @in: input image
+ * @out: output image
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Optional arguments:
+ *
+ * @background: colour for new pixels
+ *
+ * Take the last band of @in as an alpha and use it to blend the
+ * remaining channels with @background. 
+ *
+ * The alpha channel is 0 - 255 for
+ * integer images and 0 - 1 for float images, where 255 means 100% image and 0
+ * means 100% background.  Non-complex images only.
+ * @background defaults to zero (black).
+ *
+ * Useful for flattening PNG images to RGB.
+ *
+ * See also: pngload().
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int
+vips_flatten( VipsImage *in, VipsImage **out, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, out );
+	result = vips_call_split( "flatten", ap, in, out );
+	va_end( ap );
+
+	return( result );
+}

libvips/include/vips/conversion.h

@@ -216,10 +216,12 @@ int vips_black( VipsImage **out, int width, int height, ... )
 	__attribute__((sentinel));
 int vips_rot( VipsImage *in, VipsImage **out, VipsAngle angle, ... )
 	__attribute__((sentinel));
+
 int vips_ifthenelse( VipsImage *cond, VipsImage *in1, VipsImage *in2, 
 	VipsImage **out, ... )
 	__attribute__((sentinel));
-
+int vips_flatten( VipsImage *in, VipsImage **out, ... )
+	__attribute__((sentinel));
 
 
 

libvips/include/vips/internal.h

@@ -270,7 +270,8 @@ int im__fmaskcir( VipsImage *out, VipsMaskType flag, va_list ap );
 /* inplace
  */
 
-VipsPel *im__vector_to_ink( const char *domain, VipsImage *im, int n, double *vec );
+VipsPel *vips__vector_to_ink( const char *domain, 
+	VipsImage *im, double *vec, int n );
 VipsImage *im__inplace_base( const char *domain, 
 	VipsImage *main, VipsImage *sub, VipsImage *out );