new hist class structure

TODO

@@ -1,3 +1,12 @@
+- VipsHistogram takes many inputs, all of them hists and includes a
+  buffer-processing class member 
+
+  VipsHistUnary adds a single input
+
+  VipsHistNorm subclasses that
+
+
+
 - im_histspec() is a binary hist operator ... need many inputs for
   VipsHistogram and VipsHistBuffer
 

libvips/arithmetic/arithmetic.c

@@ -545,13 +545,15 @@ vips_arithmetic_build( VipsObject *object )
 	 */
 	arithmetic->ready = size;
 
-	if( vips_image_copy_fields_array( arithmetic->out, size ) ) 
+	if( vips_image_copy_fields_array( arithmetic->out, 
+		arithmetic->ready ) ) 
 		return( -1 );
         vips_demand_hint_array( arithmetic->out, 
-		VIPS_DEMAND_STYLE_THINSTRIP, size );
+		VIPS_DEMAND_STYLE_THINSTRIP, arithmetic->ready );
 
-	arithmetic->out->Bands = size[0]->Bands;
+	arithmetic->out->Bands = arithmetic->ready[0]->Bands;
-	arithmetic->out->BandFmt = aclass->format_table[size[0]->BandFmt];
+	arithmetic->out->BandFmt = 
+		aclass->format_table[arithmetic->ready[0]->BandFmt];
 
 	if( vips_image_generate( arithmetic->out,
 		vips_start_many, vips_arithmetic_gen, vips_stop_many, 

libvips/arithmetic/unary.c

@@ -86,7 +86,7 @@ vips_unary_class_init( VipsUnaryClass *class )
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 
-		_( "Input image argument" ),
+		_( "Input image" ),
 		VIPS_ARGUMENT_REQUIRED_INPUT,
 		G_STRUCT_OFFSET( VipsUnary, in ) );
 

libvips/histogram/Makefile.am

@@ -4,8 +4,8 @@ libhistogram_la_SOURCES = \
 	histogram.c \
 	phistogram.h \
 	maplut.c \
-	hist_buffer.c \
+	hist_unary.c \
-	hist_buffer.h \
+	hist_unary.h \
 	hist_cum.c \
 	hist_norm.c \
 	hist_equal.c \

libvips/histogram/hist_buffer.c

@@ -1,117 +0,0 @@
-/* a hist operation implemented as a buffer processor
- *
- * properties:
- * 	- single hist to single hist
- */
-
-/*
-
-    Copyright (C) 1991-2005 The National Gallery
-
-    This library 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 2.1 of the License, or (at your option) any later version.
-
-    This library 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 library; if not, write to the Free Software
-    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-    02110-1301  USA
-
- */
-
-/*
-
-    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
-
- */
-
-/*
-#define DEBUG
- */
-
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif /*HAVE_CONFIG_H*/
-#include <vips/intl.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-
-#include <vips/vips.h>
-#include <vips/internal.h>
-
-#include "phistogram.h"
-#include "hist_buffer.h"
-
-G_DEFINE_ABSTRACT_TYPE( VipsHistBuffer, vips_hist_buffer, VIPS_TYPE_HISTOGRAM );
-
-static int
-vips_hist_buffer_build( VipsObject *object )
-{
-	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
-	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
-	VipsHistBuffer *hist_buffer = VIPS_HIST_BUFFER( object );
-	VipsHistBufferClass *hclass = VIPS_HIST_BUFFER_GET_CLASS( hist_buffer );
-
-	VipsPel *outbuf;		
-
-#ifdef DEBUG
-	printf( "vips_hist_buffer_build: " );
-	vips_object_print_name( object );
-	printf( "\n" );
-#endif /*DEBUG*/
-
-	if( VIPS_OBJECT_CLASS( vips_hist_buffer_parent_class )->
-		build( object ) )
-		return( -1 );
-
-	if( vips_check_hist( class->nickname, histogram->in ) ||
-		vips_check_uncoded( class->nickname, histogram->in ) )
-		return( -1 ); 
-
-	if( vips_image_wio_input( histogram->in ) ||
-		vips_image_copy_fields( histogram->out, histogram->in ) ) 
-		return( -1 );
-
-	histogram->out->Xsize = VIPS_IMAGE_N_PELS( histogram->in );
-	histogram->out->Ysize = 1;
-	if( hclass->format_table ) 
-		histogram->out->BandFmt = 
-			hclass->format_table[histogram->in->BandFmt];
-
-	if( !(outbuf = vips_malloc( object, 
-		VIPS_IMAGE_SIZEOF_LINE( histogram->out ))) )
-                return( -1 );
-
-	hclass->process( hist_buffer, 
-		outbuf, VIPS_IMAGE_ADDR( histogram->in, 0, 0 ), 
-		histogram->in->Xsize );
-
-	if( vips_image_write_line( histogram->out, 0, outbuf ) )
-		return( -1 ); 
-
-	return( 0 );
-}
-
-static void
-vips_hist_buffer_class_init( VipsHistBufferClass *class )
-{
-	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
-
-	vobject_class->nickname = "hist_buffer";
-	vobject_class->description = _( "hist_buffer operations" );
-	vobject_class->build = vips_hist_buffer_build;
-
-}
-
-static void
-vips_hist_buffer_init( VipsHistBuffer *hist_buffer )
-{
-}

libvips/histogram/hist_cum.c

@@ -61,16 +61,16 @@
 #include <vips/vips.h>
 
 #include "phistogram.h"
-#include "hist_buffer.h"
+#include "hist_unary.h"
 
-typedef VipsHistBuffer VipsHistCum;
+typedef VipsHistUnary VipsHistCum;
-typedef VipsHistBufferClass VipsHistCumClass;
+typedef VipsHistUnaryClass VipsHistCumClass;
 
-G_DEFINE_TYPE( VipsHistCum, vips_hist_cum, VIPS_TYPE_HIST_BUFFER );
+G_DEFINE_TYPE( VipsHistCum, vips_hist_cum, VIPS_TYPE_HIST_UNARY );
 
 #define ACCUMULATE( ITYPE, OTYPE ) { \
 	for( b = 0; b < nb; b++ ) { \
-		ITYPE *p = (ITYPE *) in; \
+		ITYPE *p = (ITYPE *) in[0]; \
 		OTYPE *q = (OTYPE *) out; \
 		OTYPE total; \
 		\
@@ -83,18 +83,17 @@ G_DEFINE_TYPE( VipsHistCum, vips_hist_cum, VIPS_TYPE_HIST_BUFFER );
 }
 
 static void
-vips_hist_cum_buffer( VipsHistBuffer *hist_buffer, 
+vips_hist_cum_buffer( VipsHistogram *histogram, 
-	VipsPel *out, VipsPel *in, int width )
+	VipsPel *out, VipsPel **in, int width )
 {
-	VipsHistogram *histogram = VIPS_HISTOGRAM( hist_buffer );
+	const int bands = vips_image_get_bands( histogram->ready[0] );
-	const int bands = vips_image_get_bands( histogram->in );
+	const int nb = vips_bandfmt_iscomplex( histogram->ready[0]->BandFmt ) ? 
-	const int nb = vips_bandfmt_iscomplex( histogram->in->BandFmt ) ? 
 		bands * 2 : bands;
 	int mx = width * nb;
 
 	int x, b; 
 
-	switch( vips_image_get_format( histogram->in ) ) {
+	switch( vips_image_get_format( histogram->ready[0] ) ) {
         case VIPS_FORMAT_CHAR: 		
 		ACCUMULATE( signed char, signed int ); break; 
         case VIPS_FORMAT_UCHAR: 		
@@ -142,7 +141,7 @@ static void
 vips_hist_cum_class_init( VipsHistCumClass *class )
 {
 	VipsObjectClass *object_class = (VipsObjectClass *) class;
-	VipsHistBufferClass *hclass = VIPS_HIST_BUFFER_CLASS( class );
+	VipsHistogramClass *hclass = VIPS_HISTOGRAM_CLASS( class );
 
 	object_class->nickname = "hist_cum";
 	object_class->description = _( "form cumulative histogram" );

libvips/histogram/hist_equal.c

@@ -53,37 +53,39 @@
 
 #include <vips/vips.h>
 
-#include "phistogram.h"
-
 typedef struct _VipsHistEqual { 
-	VipsHistogram parent_instance;
+	VipsOperation parent_instance;
+
+	VipsImage *in;
+	VipsImage *out;
 
 	/* -1 for all bands, or the band we scan.
 	 */
 	int which;
 } VipsHistEqual;
 
-typedef VipsHistogramClass VipsHistEqualClass;
+typedef VipsOperationClass VipsHistEqualClass;
 
-G_DEFINE_TYPE( VipsHistEqual, vips_hist_equal, VIPS_TYPE_HISTOGRAM );
+G_DEFINE_TYPE( VipsHistEqual, vips_hist_equal, VIPS_TYPE_OPERATION );
 
 static int
 vips_hist_equal_build( VipsObject *object )
 {
-	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
+	VipsHistEqual *equal = (VipsHistEqual *) object; 
-	VipsHistEqual *hist_equal = (VipsHistEqual *) histogram; 
 	VipsImage **t = (VipsImage **) vips_object_local_array( object, 4 );
 
+	g_object_set( equal, "out", vips_image_new(), NULL ); 
+
 	if( VIPS_OBJECT_CLASS( vips_hist_equal_parent_class )->build( object ) )
 		return( -1 );
 
-	if( vips_hist_find( histogram->in, &t[0], 
+	if( vips_hist_find( equal->in, &t[0], 
-			"band", hist_equal->which,
+			"band", equal->which,
 			NULL ) ||
 		vips_hist_cum( t[0], &t[1], NULL ) ||
 		vips_hist_norm( t[1], &t[2], NULL ) ||
-		vips_maplut( histogram->in, &t[3], t[2], NULL ) ||
+		vips_maplut( equal->in, &t[3], t[2], NULL ) ||
-		vips_image_write( t[3], histogram->out ) )
+		vips_image_write( t[3], equal->out ) )
 		return( -1 );
 
 	return( 0 );
@@ -102,6 +104,18 @@ vips_hist_equal_class_init( VipsHistEqualClass *class )
 	object_class->description = _( "histogram equalisation" );
 	object_class->build = vips_hist_equal_build;
 
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistEqual, in ) );
+
+	VIPS_ARG_IMAGE( class, "out", 2, 
+		_( "Output" ), 
+		_( "Output image" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsHistEqual, out ) );
+
 	VIPS_ARG_INT( class, "band", 110, 
 		_( "Band" ), 
 		_( "Equalise with this band" ),
@@ -111,9 +125,9 @@ vips_hist_equal_class_init( VipsHistEqualClass *class )
 }
 
 static void
-vips_hist_equal_init( VipsHistEqual *hist_equal )
+vips_hist_equal_init( VipsHistEqual *equal )
 {
-	hist_equal->which = -1;
+	equal->which = -1;
 }
 
 /**

libvips/histogram/hist_norm.c

@@ -60,17 +60,21 @@
 
 #include <vips/vips.h>
 
-#include "phistogram.h"
+typedef struct _VipsHistNorm {
+	VipsOperation parent_instance;
 
-typedef VipsHistogram VipsHistNorm;
+	VipsImage *in;
-typedef VipsHistogramClass VipsHistNormClass;
+	VipsImage *out;
+} VipsHistNorm;
 
-G_DEFINE_TYPE( VipsHistNorm, vips_hist_norm, VIPS_TYPE_HISTOGRAM );
+typedef VipsOperationClass VipsHistNormClass;
+
+G_DEFINE_TYPE( VipsHistNorm, vips_hist_norm, VIPS_TYPE_OPERATION );
 
 static int
 vips_hist_norm_build( VipsObject *object )
 {
-	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
+	VipsHistNorm *norm = (VipsHistNorm *) object;
 	VipsImage **t = (VipsImage **) vips_object_local_array( object, 3 );
 
 	guint64 px;
@@ -79,18 +83,20 @@ vips_hist_norm_build( VipsObject *object )
 	int y;
 	VipsBandFormat fmt;
 
+	g_object_set( norm, "out", vips_image_new(), NULL ); 
+
 	if( VIPS_OBJECT_CLASS( vips_hist_norm_parent_class )->build( object ) )
 		return( -1 );
 
 	/* Need max for each channel.
 	 */
-	if( vips_stats( histogram->in, &t[0], NULL ) )
+	if( vips_stats( norm->in, &t[0], NULL ) )
 		return( -1 ); 
 
 	/* Scale each channel by px / channel max
 	 */
-	px = VIPS_IMAGE_N_PELS( histogram->in );
+	px = VIPS_IMAGE_N_PELS( norm->in );
-	bands = histogram->in->Bands;
+	bands = norm->in->Bands;
 	if( !(a = VIPS_ARRAY( object, bands, double )) ||
 		!(b = VIPS_ARRAY( object, bands, double )) )
 		return( -1 );
@@ -99,7 +105,7 @@ vips_hist_norm_build( VipsObject *object )
 		b[y] = 0;
 	}
 
-	if( vips_linear( histogram->in, &t[1], a, b, bands, NULL ) )
+	if( vips_linear( norm->in, &t[1], a, b, bands, NULL ) )
 		return( -1 );
 
 	/* Make output format as small as we can.
@@ -112,7 +118,7 @@ vips_hist_norm_build( VipsObject *object )
 		fmt = VIPS_FORMAT_UINT;
 
 	if( vips_cast( t[1], &t[2], fmt, NULL ) ||
-		vips_image_write( t[2], histogram->out ) )
+		vips_image_write( t[2], norm->out ) )
 		return( -1 );
 
 	return( 0 );
@@ -121,11 +127,27 @@ vips_hist_norm_build( VipsObject *object )
 static void
 vips_hist_norm_class_init( VipsHistNormClass *class )
 {
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
 	VipsObjectClass *object_class = (VipsObjectClass *) class;
 
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
 	object_class->nickname = "hist_norm";
 	object_class->description = _( "normalise histogram" );
 	object_class->build = vips_hist_norm_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistNorm, in ) );
+
+	VIPS_ARG_IMAGE( class, "out", 2, 
+		_( "Output" ), 
+		_( "Output image" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsHistNorm, out ) );
 }
 
 static void

libvips/histogram/hist_plot.c

@@ -298,20 +298,28 @@ im_histplot( IMAGE *in, IMAGE *out )
 	return( 0 );
 }
 
-typedef VipsHistogram VipsHistPlot;
+typedef struct _VipsHistPlot {
-typedef VipsHistogramClass VipsHistPlotClass;
+	VipsOperation parent_instance;
 
-G_DEFINE_TYPE( VipsHistPlot, vips_hist_plot, VIPS_TYPE_HISTOGRAM );
+	VipsImage *in;
+	VipsImage *out;
+} VipsHistPlot;
+
+typedef VipsOperationClass VipsHistPlotClass;
+
+G_DEFINE_TYPE( VipsHistPlot, vips_hist_plot, VIPS_TYPE_OPERATION );
 
 static int
 vips_hist_plot_build( VipsObject *object )
 {
-	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
+	VipsHistPlot *plot = (VipsHistPlot *) object;
+
+	g_object_set( plot, "out", vips_image_new(), NULL ); 
 
 	if( VIPS_OBJECT_CLASS( vips_hist_plot_parent_class )->build( object ) )
 		return( -1 );
 
-	if( im_histplot( histogram->in, histogram->out ) )
+	if( im_histplot( plot->in, plot->out ) )
 		return( -1 ); 
 
 	return( 0 );
@@ -320,11 +328,27 @@ vips_hist_plot_build( VipsObject *object )
 static void
 vips_hist_plot_class_init( VipsHistPlotClass *class )
 {
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
 	VipsObjectClass *object_class = (VipsObjectClass *) class;
 
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
 	object_class->nickname = "hist_plot";
 	object_class->description = _( "plot histogram" );
 	object_class->build = vips_hist_plot_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistPlot, in ) );
+
+	VIPS_ARG_IMAGE( class, "out", 2, 
+		_( "Output" ), 
+		_( "Output image" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsHistPlot, out ) );
 }
 
 static void

libvips/histogram/hist_unary.c

@@ -0,0 +1,99 @@
+/* a hist operation implemented as a unary processor
+ *
+ * properties:
+ * 	- single hist to single hist
+ */
+
+/*
+
+    Copyright (C) 1991-2005 The National Gallery
+
+    This library 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 2.1 of the License, or (at your option) any later version.
+
+    This library 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 library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+/*
+#define DEBUG
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include <vips/vips.h>
+#include <vips/internal.h>
+
+#include "phistogram.h"
+#include "hist_unary.h"
+
+G_DEFINE_ABSTRACT_TYPE( VipsHistUnary, vips_hist_unary, VIPS_TYPE_HISTOGRAM );
+
+static int
+vips_hist_unary_build( VipsObject *object )
+{
+	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
+	VipsHistUnary *unary = VIPS_HIST_UNARY( object );
+
+	histogram->n = 1;
+	histogram->in = (VipsImage **) vips_object_local_array( object, 1 );
+	histogram->in[0] = unary->in;
+
+	if( histogram->in[0] )
+		g_object_ref( histogram->in[0] );
+
+	if( VIPS_OBJECT_CLASS( vips_hist_unary_parent_class )->
+		build( object ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_hist_unary_class_init( VipsHistUnaryClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	vobject_class->nickname = "hist_unary";
+	vobject_class->description = _( "hist_unary operations" );
+	vobject_class->build = vips_hist_unary_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistUnary, in ) );
+
+}
+
+static void
+vips_hist_unary_init( VipsHistUnary *hist_unary )
+{
+}

libvips/histogram/hist_unary.h

@@ -1,4 +1,4 @@
-/* base class for all hist_buffer operations
+/* base class for all hist_unary operations
  */
 
 /*
@@ -28,8 +28,8 @@
 
  */
 
-#ifndef VIPS_PHIST_BUFFER_H
+#ifndef VIPS_PHIST_UNARY_H
-#define VIPS_PHIST_BUFFER_H
+#define VIPS_PHIST_UNARY_H
 
 #ifdef __cplusplus
 extern "C" {
@@ -37,46 +37,39 @@ extern "C" {
 
 #include <vips/vector.h>
 
-#define VIPS_TYPE_HIST_BUFFER (vips_hist_buffer_get_type())
+#define VIPS_TYPE_HIST_UNARY (vips_hist_unary_get_type())
-#define VIPS_HIST_BUFFER( obj ) \
+#define VIPS_HIST_UNARY( obj ) \
 	(G_TYPE_CHECK_INSTANCE_CAST( (obj), \
-		VIPS_TYPE_HIST_BUFFER, VipsHistBuffer ))
+		VIPS_TYPE_HIST_UNARY, VipsHistUnary ))
-#define VIPS_HIST_BUFFER_CLASS( klass ) \
+#define VIPS_HIST_UNARY_CLASS( klass ) \
 	(G_TYPE_CHECK_CLASS_CAST( (klass), \
-		VIPS_TYPE_HIST_BUFFER, VipsHistBufferClass))
+		VIPS_TYPE_HIST_UNARY, VipsHistUnaryClass))
-#define VIPS_IS_HIST_BUFFER( obj ) \
+#define VIPS_IS_HIST_UNARY( obj ) \
-	(G_TYPE_CHECK_INSTANCE_TYPE( (obj), VIPS_TYPE_HIST_BUFFER ))
+	(G_TYPE_CHECK_INSTANCE_TYPE( (obj), VIPS_TYPE_HIST_UNARY ))
-#define VIPS_IS_HIST_BUFFER_CLASS( klass ) \
+#define VIPS_IS_HIST_UNARY_CLASS( klass ) \
-	(G_TYPE_CHECK_CLASS_TYPE( (klass), VIPS_TYPE_HIST_BUFFER ))
+	(G_TYPE_CHECK_CLASS_TYPE( (klass), VIPS_TYPE_HIST_UNARY ))
-#define VIPS_HIST_BUFFER_GET_CLASS( obj ) \
+#define VIPS_HIST_UNARY_GET_CLASS( obj ) \
 	(G_TYPE_INSTANCE_GET_CLASS( (obj), \
-		VIPS_TYPE_HIST_BUFFER, VipsHistBufferClass ))
+		VIPS_TYPE_HIST_UNARY, VipsHistUnaryClass ))
 
-struct _VipsHistBuffer;
+typedef struct _VipsHistUnary {
-typedef void (*VipsHistBufferProcessFn)( struct _VipsHistBuffer *hist_buffer, 
-	VipsPel *out, VipsPel *in, int width );
-
-typedef struct _VipsHistBuffer {
 	VipsHistogram parent_instance;
 
-} VipsHistBuffer;
+	VipsImage *in;
 
-typedef struct _VipsHistBufferClass {
+} VipsHistUnary;
+
+typedef struct _VipsHistUnaryClass {
 	VipsHistogramClass parent_class;
 
-	/* For each input format, what output format. 
+} VipsHistUnaryClass;
-	 */
-	const VipsBandFormat *format_table;
 
-	VipsHistBufferProcessFn process;
+GType vips_hist_unary_get_type( void );
-} VipsHistBufferClass;
-
-GType vips_hist_buffer_get_type( void );
 
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/
 
-#endif /*VIPS_PHIST_BUFFER_H*/
+#endif /*VIPS_PHIST_UNARY_H*/
 
 

libvips/histogram/histogram.c

@@ -76,10 +76,50 @@
 
 G_DEFINE_ABSTRACT_TYPE( VipsHistogram, vips_histogram, VIPS_TYPE_OPERATION );
 
+/* sizealike by expanding in just one dimension.
+ */
+static int
+vips__hist_sizealike_vec( VipsImage **in, VipsImage **out, int n )
+{
+	int i;
+	int max_size;
+
+	g_assert( n >= 1 );
+
+	max_size = VIPS_MAX( in[0]->Xsize, in[0]->Ysize );
+	for( i = 1; i < n; i++ ) 
+		max_size = VIPS_MAX( max_size, 
+			VIPS_MAX( in[0]->Xsize, in[0]->Ysize ) );
+
+	for( i = 0; i < n; i++ ) 
+		if( in[i]->Ysize == 1 ) {
+			if( vips_embed( in[i], &out[i], 
+				0, 0, max_size, 1, NULL ) )
+				return( -1 );
+		}
+		else {
+			if( vips_embed( in[i], &out[i], 
+				0, 0, 1, max_size, NULL ) )
+				return( -1 );
+		}
+
+	return( 0 );
+}
+
 static int
 vips_histogram_build( VipsObject *object )
 {
 	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
+	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
+	VipsHistogramClass *hclass = VIPS_HISTOGRAM_GET_CLASS( histogram );
+
+	VipsImage **format;
+	VipsImage **band;
+	VipsImage **size;
+
+	VipsPel *outbuf;		
+	VipsPel **inbuf;		
+	int i;
 
 #ifdef DEBUG
 	printf( "vips_histogram_build: " );
@@ -90,8 +130,64 @@ vips_histogram_build( VipsObject *object )
 	if( VIPS_OBJECT_CLASS( vips_histogram_parent_class )->build( object ) )
 		return( -1 );
 
+	g_assert( histogram->n > 0 ); 
+
+	/* Must be NULL-terminated.
+	 */
+	g_assert( !histogram->in[histogram->n] ); 
+
+	format = (VipsImage **) vips_object_local_array( object, histogram->n );
+	band = (VipsImage **) vips_object_local_array( object, histogram->n );
+	size = (VipsImage **) vips_object_local_array( object, histogram->n );
+
 	g_object_set( histogram, "out", vips_image_new(), NULL ); 
 
+	for( i = 0; i < histogram->n; i++ ) 
+		if( vips_check_uncoded( class->nickname, histogram->in[i] ) ||
+			vips_check_hist( class->nickname, histogram->in[i] ) )
+			return( -1 ); 
+
+	/* Cast our input images up to a common format, bands and size.
+	 */
+	if( vips__formatalike_vec( histogram->in, format, histogram->n ) ||
+		vips__bandalike_vec( class->nickname, 
+			format, band, histogram->n, 1 ) ||
+		vips__hist_sizealike_vec( band, size, histogram->n ) ) 
+		return( -1 );
+
+	/* Keep a copy of the processed images here for subclasses.
+	 */
+	histogram->ready = size;
+
+	if( vips_image_copy_fields_array( histogram->out, histogram->ready ) ) 
+		return( -1 );
+        vips_demand_hint_array( histogram->out, 
+		VIPS_DEMAND_STYLE_THINSTRIP, histogram->ready );
+
+	histogram->out->Xsize = VIPS_IMAGE_N_PELS( histogram->ready[0] );
+	histogram->out->Ysize = 1;
+	if( hclass->format_table ) 
+		histogram->out->BandFmt = 
+			hclass->format_table[histogram->ready[0]->BandFmt];
+
+	if( !(outbuf = vips_malloc( object, 
+		VIPS_IMAGE_SIZEOF_LINE( histogram->out ))) )
+                return( -1 );
+
+	if( !(inbuf = VIPS_ARRAY( object, histogram->n + 1, VipsPel * )) )
+                return( -1 );
+	for( i = 0; i < histogram->n; i++ ) {
+		if( vips_image_wio_input( histogram->ready[i] ) )
+			return( -1 ); 
+		inbuf[i] = VIPS_IMAGE_ADDR( histogram->in[i], 0, 0 );
+	}
+	inbuf[i] = NULL; 
+
+	hclass->process( histogram, outbuf, inbuf, histogram->ready[0]->Xsize );
+
+	if( vips_image_write_line( histogram->out, 0, outbuf ) )
+		return( -1 ); 
+
 	return( 0 );
 }
 
@@ -108,13 +204,10 @@ vips_histogram_class_init( VipsHistogramClass *class )
 	vobject_class->description = _( "histogram operations" );
 	vobject_class->build = vips_histogram_build;
 
-	VIPS_ARG_IMAGE( class, "in", 0, 
+	/* Inputs set by subclassess.
-		_( "Input" ), 
+	 */
-		_( "Input image" ),
-		VIPS_ARGUMENT_REQUIRED_INPUT, 
-		G_STRUCT_OFFSET( VipsHistogram, in ) );
 
-	VIPS_ARG_IMAGE( class, "out", 1, 
+	VIPS_ARG_IMAGE( class, "out", 10, 
 		_( "Output" ), 
 		_( "Output image" ),
 		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
@@ -125,6 +218,9 @@ vips_histogram_class_init( VipsHistogramClass *class )
 static void
 vips_histogram_init( VipsHistogram *histogram )
 {
+	/* Sanity check this above.
+	 */
+	histogram->n = -1;
 }
 
 /* Called from iofuncs to init all operations in this dir. Use a plugin system

libvips/histogram/maplut.c

@@ -71,11 +71,11 @@
 
 #include <vips/vips.h>
 
-#include "phistogram.h"
-
 typedef struct _VipsMaplut {
-	VipsHistogram parent_instance;
+	VipsOperation parent_instance;
 
+	VipsImage *in;
+	VipsImage *out;
 	VipsImage *lut;
 
 	int fmt;		/* LUT image BandFmt */
@@ -88,9 +88,9 @@ typedef struct _VipsMaplut {
 
 } VipsMaplut;
 
-typedef VipsHistogramClass VipsMaplutClass;
+typedef VipsOperationClass VipsMaplutClass;
 
-G_DEFINE_TYPE( VipsMaplut, vips_maplut, VIPS_TYPE_HISTOGRAM );
+G_DEFINE_TYPE( VipsMaplut, vips_maplut, VIPS_TYPE_OPERATION );
 
 static void
 vips_maplut_preeval( VipsImage *image, VipsProgress *progress, 
@@ -410,26 +410,26 @@ vips_maplut_start( VipsImage *out, void *a, void *b )
  */
 #define outer_switch( UCHAR_F, UCHAR_FC, GEN_F, GEN_FC ) \
 	switch( maplut->fmt ) { \
-	case VIPS_FORMAT_UCHAR:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_UCHAR: \
-						unsigned char ); break; \
+		inner_switch( UCHAR_F, GEN_F, unsigned char ); break; \
-	case VIPS_FORMAT_CHAR:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_CHAR:\
-						char ); break; \
+		inner_switch( UCHAR_F, GEN_F, char ); break; \
-	case VIPS_FORMAT_USHORT:	inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_USHORT: \
-						unsigned short ); break; \
+		inner_switch( UCHAR_F, GEN_F, unsigned short ); break; \
-	case VIPS_FORMAT_SHORT:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_SHORT: \
-						short ); break; \
+		inner_switch( UCHAR_F, GEN_F, short ); break; \
-	case VIPS_FORMAT_UINT:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_UINT: \
-						unsigned int ); break; \
+		inner_switch( UCHAR_F, GEN_F, unsigned int ); break; \
-	case VIPS_FORMAT_INT:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_INT: \
-						int ); break; \
+		inner_switch( UCHAR_F, GEN_F, int ); break; \
-	case VIPS_FORMAT_FLOAT:		inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_FLOAT: \
-						float ); break; \
+		inner_switch( UCHAR_F, GEN_F, float ); break; \
-	case VIPS_FORMAT_DOUBLE:	inner_switch( UCHAR_F, GEN_F, \
+	case VIPS_FORMAT_DOUBLE: \
-						double ); break; \
+		inner_switch( UCHAR_F, GEN_F, double ); break; \
-	case VIPS_FORMAT_COMPLEX:	inner_switch( UCHAR_FC, GEN_FC, \
+	case VIPS_FORMAT_COMPLEX: \
-						float ); break; \
+		inner_switch( UCHAR_FC, GEN_FC, float ); break; \
-	case VIPS_FORMAT_DPCOMPLEX:	inner_switch( UCHAR_FC, GEN_FC, \
+	case VIPS_FORMAT_DPCOMPLEX: \
-						double ); break; \
+		inner_switch( UCHAR_FC, GEN_FC, double ); break; \
 	default: \
 		g_assert( 0 ); \
 	}
@@ -507,7 +507,6 @@ static int
 vips_maplut_build( VipsObject *object )
 {
 	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
-	VipsHistogram *histogram = VIPS_HISTOGRAM( object );
 	VipsMaplut *maplut = (VipsMaplut *) object;
 	VipsImage **t = (VipsImage **) vips_object_local_array( object, 1 );
 
@@ -519,7 +518,7 @@ vips_maplut_build( VipsObject *object )
 	if( VIPS_OBJECT_CLASS( vips_maplut_parent_class )->build( object ) )
 		return( -1 );
 
-	in = histogram->in;
+	in = maplut->in;
 	lut = maplut->lut;
 
 	if( vips_check_hist( class->nickname, lut ) ||
@@ -538,17 +537,17 @@ vips_maplut_build( VipsObject *object )
 		vips_image_pio_input( in ) )
 		return( -1 );
 
-	if( vips_image_copy_fieldsv( histogram->out, in, lut, NULL ) )
+	if( vips_image_copy_fieldsv( maplut->out, in, lut, NULL ) )
 		return( -1 );
-	vips_demand_hint( histogram->out, VIPS_DEMAND_STYLE_THINSTRIP, 
+	vips_demand_hint( maplut->out, VIPS_DEMAND_STYLE_THINSTRIP, 
 		in, lut, NULL );
-	histogram->out->BandFmt = lut->BandFmt;
+	maplut->out->BandFmt = lut->BandFmt;
 
 	/* Output has same number of bands as LUT, unless LUT has 1 band, in
 	 * which case output has same number of bands as input.
 	 */
 	if( lut->Bands != 1 )
-		histogram->out->Bands = lut->Bands;
+		maplut->out->Bands = lut->Bands;
 
 	g_signal_connect( in, "preeval", 
 		G_CALLBACK( vips_maplut_preeval ), maplut );
@@ -583,7 +582,7 @@ vips_maplut_build( VipsObject *object )
 			q += maplut->es;
 		}
 
-	if( vips_image_generate( histogram->out,
+	if( vips_image_generate( maplut->out,
 		vips_maplut_start, vips_maplut_gen, vips_maplut_stop, 
 		in, maplut ) )
 		return( -1 );
@@ -607,7 +606,19 @@ vips_maplut_class_init( VipsMaplutClass *class )
 
 	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
-	VIPS_ARG_IMAGE( class, "lut", 2, 
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsMaplut, in ) );
+
+	VIPS_ARG_IMAGE( class, "out", 2, 
+		_( "Output" ), 
+		_( "Output image" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsMaplut, out ) );
+
+	VIPS_ARG_IMAGE( class, "lut", 3, 
 		_( "LUT" ), 
 		_( "Look-up table image" ),
 		VIPS_ARGUMENT_REQUIRED_INPUT,

libvips/histogram/phistogram.h

@@ -1,4 +1,6 @@
 /* base class for all histogram operations
+ *
+ * many hists in, one hist out, a buffer processing function in the class
  */
 
 /*
@@ -52,18 +54,35 @@ extern "C" {
 	(G_TYPE_INSTANCE_GET_CLASS( (obj), \
 		VIPS_TYPE_HISTOGRAM, VipsHistogramClass ))
 
-typedef struct _VipsHistogram {
+typedef struct _VipsHistogram VipsHistogram;
-	VipsOperation parent_instance;
 
-	VipsImage *in;
+typedef void (*VipsHistogramProcessFn)( VipsHistogram *histogram, 
+	VipsPel *out, VipsPel **in, int width );
+
+struct _VipsHistogram {
+	VipsOperation parent_instance;
 
 	VipsImage *out;
 
-} VipsHistogram;
+	/* NULL-terminated array of input images. 
+	 */
+	VipsImage **in;
+	int n;
+
+	/* ... and transformed ready for processing.
+	 */
+	VipsImage **ready; 
+};
 
 typedef struct _VipsHistogramClass {
 	VipsOperationClass parent_class;
 
+	/* For each input format, what output format. 
+	 */
+	const VipsBandFormat *format_table;
+
+	VipsHistogramProcessFn process;
+
 } VipsHistogramClass;
 
 GType vips_histogram_get_type( void );

libvips/iofuncs/object.c

@@ -2370,10 +2370,11 @@ vips_object_local_array_cb( GObject *parent, VipsObjectLocal *local )
  * @n: array size
  *
  * Make an array of NULL VipsObject pointers. When @parent closes, every
- * non-NULL pointer in the array will be unreffed and the arraqy will be
+ * non-NULL pointer in the array will be unreffed and the array will be
- * freed.
+ * freed. Handy for creating a set of temporary images for a function.
- * Handy for creating a 
+ *
- * set of temporary images for a function.
+ * The array is NULL-terminated, ie. contains an extra NULL element at the
+ * end. 
  *
  * Example:
  *