diff --git a/ChangeLog b/ChangeLog
index 3d8ac188..b5a2ee69 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,7 +5,7 @@
 - rewrite im_buildlut(), im_identity*(), im_maplut(), im_falsecolour(),
   im_gammacorrect(), im_histgr(), im_histcum(), im_histnorm(), im_heq(),
   im_histnD(), im_histindexed(), im_histspec(), im_invertlut(), im_lhisteq(),
-  im_stdif(), im_project() as classes
+  im_stdif(), im_project(), im_tone_build*() as classes
 - vips_hist_local(), vips_stdif() do any number of bands
 - thin vips8 wrapper for im_histplot()
 - added vips_error_freeze() / vips_error_thaw()
diff --git a/TODO b/TODO
index a3db3007..28b06d64 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,5 @@
+- need to do im_profile() before we can finish hist_percent()
+
 - try:
 
 	$ vips extract_band 50310.svs x.tif[pyramid,tile,compression=jpeg,tile-width=256,tile-height=256] 0 --n 3
diff --git a/libvips/create/Makefile.am b/libvips/create/Makefile.am
index e5624dd2..60812e38 100644
--- a/libvips/create/Makefile.am
+++ b/libvips/create/Makefile.am
@@ -5,6 +5,7 @@ libcreate_la_SOURCES = \
 	pcreate.h \
 	buildlut.c \
 	invertlut.c \
+	tonelut.c \
 	identity.c \
 	point.c \
 	point.h \
diff --git a/libvips/create/create.c b/libvips/create/create.c
index d9543933..61b6e234 100644
--- a/libvips/create/create.c
+++ b/libvips/create/create.c
@@ -122,6 +122,7 @@ vips_create_operation_init( void )
 	extern GType vips_sines_get_type( void ); 
 	extern GType vips_buildlut_get_type( void ); 
 	extern GType vips_invertlut_get_type( void ); 
+	extern GType vips_tonelut_get_type( void ); 
 	extern GType vips_identity_get_type( void ); 
 
 	vips_black_get_type();
@@ -136,6 +137,7 @@ vips_create_operation_init( void )
 	vips_sines_get_type(); 
 	vips_buildlut_get_type(); 
 	vips_invertlut_get_type(); 
+	vips_tonelut_get_type(); 
 	vips_identity_get_type(); 
 }
 
diff --git a/libvips/create/tonelut.c b/libvips/create/tonelut.c
new file mode 100644
index 00000000..c1ce41ee
--- /dev/null
+++ b/libvips/create/tonelut.c
@@ -0,0 +1,356 @@
+/* Build a tone curve. 
+ *
+ * Author: John Cupitt
+ * Written on: 18/7/1995
+ * 17/9/96 JC
+ *	- restrictions on Ps, Pm, Ph relaxed
+ *	- restrictions on S, M, H relaxed
+ * 25/7/01 JC
+ *	- patched for im_extract_band() change
+ * 11/7/04
+ *	- generalised to im_tone_build_range() ... so you can use it for any
+ *	  image, not just LabS
+ * 26/3/10
+ * 	- cleanups
+ * 	- gtkdoc
+ * 20/9/13
+ * 	- redo as a class
+ */
+
+/*
+
+    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., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#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 "pcreate.h"
+
+typedef struct _VipsTonelut {
+	VipsCreate parent_instance;
+
+	/* Parameters for tone curve formation.
+	 */
+	double Lb, Lw;
+	double Ps, Pm, Ph; 
+	double S, M, H;
+
+	/* Range we process.
+	 */
+	int in_max;
+	int out_max;
+
+	/* Derived values.
+	 */
+	double Ls, Lm, Lh;
+} VipsTonelut;
+
+typedef VipsCreateClass VipsTonelutClass;
+
+G_DEFINE_TYPE( VipsTonelut, vips_tonelut, VIPS_TYPE_CREATE );
+
+/* Calculate shadow curve.
+ */
+static double
+shad( VipsTonelut *lut, double x )
+{
+	double x1 = (x - lut->Lb) / (lut->Ls - lut->Lb);
+	double x2 = (x - lut->Ls) / (lut->Lm - lut->Ls);
+
+	double out;
+
+	if( x < lut->Lb )
+		out = 0;
+	else if( x < lut->Ls )
+		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
+	else if( x < lut->Lm )
+		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
+	else 
+		out = 0;
+
+	return( out );
+}
+
+/* Calculate mid-tone curve.
+ */
+static double
+mid( VipsTonelut *lut, double x )
+{
+	double x1 = (x - lut->Ls) / (lut->Lm - lut->Ls);
+	double x2 = (x - lut->Lm) / (lut->Lh - lut->Lm);
+
+	double out;
+
+	if( x < lut->Ls )
+		out = 0;
+	else if( x < lut->Lm )
+		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
+	else if( x < lut->Lh )
+		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
+	else 
+		out = 0;
+
+	return( out );
+}
+
+/* Calculate highlight curve.
+ */
+static double
+high( VipsTonelut *lut, double x )
+{
+	double x1 = (x - lut->Lm) / (lut->Lh - lut->Lm);
+	double x2 = (x - lut->Lh) / (lut->Lw - lut->Lh);
+
+	double out;
+
+	if( x < lut->Lm )
+		out = 0;
+	else if( x < lut->Lh )
+		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
+	else if( x < lut->Lw )
+		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
+	else 
+		out = 0;
+
+	return( out );
+}
+
+/* Generate a point on the tone curve. Everything is 0-100.
+ */
+static double
+tone_curve( VipsTonelut *lut, double x )
+{
+	double out;
+
+	out = x + 
+		lut->S * shad( lut, x ) + 
+		lut->M * mid( lut, x ) + 
+		lut->H * high( lut, x );
+	
+	return( out );
+}
+
+static int
+vips_tonelut_build( VipsObject *object )
+{
+	VipsCreate *create = VIPS_CREATE( object );
+	VipsTonelut *lut = (VipsTonelut *) object;
+
+	int i; 
+	unsigned short buf[65536];
+
+	if( VIPS_OBJECT_CLASS( vips_tonelut_parent_class )->build( object ) )
+		return( -1 );
+
+	g_assert( lut->in_max > 0 && lut->in_max < 65536 ); 
+	g_assert( lut->out_max > 0 && lut->out_max < 65536 ); 
+
+	/* Note derived params.
+	 */
+	lut->Ls = lut->Lb + lut->Ps * (lut->Lw - lut->Lb);
+	lut->Lm = lut->Lb + lut->Pm * (lut->Lw - lut->Lb);
+	lut->Lh = lut->Lb + lut->Ph * (lut->Lw - lut->Lb);
+
+	/* Generate curve.
+	 */
+	for( i = 0; i <= lut->in_max; i++ ) {
+		int v = (lut->out_max / 100.0) * 
+			tone_curve( lut, 100.0 * i / lut->in_max );
+
+		if( v < 0 )
+			v = 0;
+		else if( v > lut->out_max )
+			v = lut->out_max;
+
+		buf[i] = v;
+	}
+
+	/* Make the output image.
+	 */
+        vips_image_init_fields( create->out,
+                lut->in_max + 1, 1, 1, 
+		VIPS_FORMAT_USHORT, VIPS_CODING_NONE, 
+		VIPS_INTERPRETATION_HISTOGRAM, 1.0, 1.0 );
+        if( vips_image_write_line( create->out, 0, (VipsPel *) buf ) ) 
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_tonelut_class_init( VipsTonelutClass *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 = "tonelut";
+	vobject_class->description = _( "build a look-up table" );
+	vobject_class->build = vips_tonelut_build;
+
+	VIPS_ARG_INT( class, "in_max", 4, 
+		_( "In-max" ), 
+		_( "Size of LUT to build" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, in_max ),
+		1, 65535, 32767 );
+
+	VIPS_ARG_INT( class, "out_max", 5, 
+		_( "Out-max" ), 
+		_( "Maximum value in output LUT" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, out_max ),
+		1, 65535, 32767 );
+
+	VIPS_ARG_DOUBLE( class, "Lb", 6, 
+		_( "Black point" ), 
+		_( "Lowest value in output" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, Lb ),
+		0, 100, 0 ); 
+
+	VIPS_ARG_DOUBLE( class, "Lw", 7, 
+		_( "White point" ), 
+		_( "Highest value in output" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, Lw ),
+		0, 100, 100 ); 
+
+	VIPS_ARG_DOUBLE( class, "Ps", 8, 
+		_( "Shadow point" ), 
+		_( "Position of shadow" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, Ps ),
+		0, 1, 0.2 ); 
+
+	VIPS_ARG_DOUBLE( class, "Pm", 9, 
+		_( "Mid-tone point" ), 
+		_( "Position of mid-tones" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, Pm ),
+		0, 1, 0.5 ); 
+
+	VIPS_ARG_DOUBLE( class, "Ph", 10, 
+		_( "Highlight point" ), 
+		_( "Position of highlights" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, Ph ),
+		0, 1, 0.8 ); 
+
+	VIPS_ARG_DOUBLE( class, "S", 11, 
+		_( "Shadow adjust" ), 
+		_( "Adjust shadows by this much" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, S ),
+		-30, 30, 0 ); 
+
+	VIPS_ARG_DOUBLE( class, "M", 12, 
+		_( "Mid-tone adjust" ), 
+		_( "Adjust mid-tones by this much" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, M ),
+		-30, 30, 0 ); 
+
+	VIPS_ARG_DOUBLE( class, "H", 13, 
+		_( "Highlight adjust" ), 
+		_( "Adjust highlights by this much" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsTonelut, H ),
+		-30, 30, 0 ); 
+
+}
+
+static void
+vips_tonelut_init( VipsTonelut *lut )
+{
+	lut->in_max = 32767; 
+	lut->out_max = 32767; 
+	lut->Lb = 0.0; 
+	lut->Lw = 100.0; 
+	lut->Ps = 0.2; 
+	lut->Pm = 0.5; 
+	lut->Ph = 0.8; 
+	lut->S = 0.0; 
+	lut->M = 0.0; 
+	lut->H = 0.0; 
+}
+
+/**
+ * vips_tonelut:
+ * @out: output image 
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Optional arguments:
+ *
+ * @in_max: input range 
+ * @out_max: output range
+ * @Lb: black-point [0-100]
+ * @Lw: white-point [0-100]
+ * @Ps: shadow point (eg. 0.2)
+ * @Pm: mid-tone point (eg. 0.5)
+ * @Ph: highlight point (eg. 0.8)
+ * @S: shadow adjustment (+/- 30)
+ * @M: mid-tone adjustment (+/- 30)
+ * @H: highlight adjustment (+/- 30)
+ *
+ * vips_tonelut() generates a tone curve for the adjustment of image 
+ * levels. It is mostly designed for adjusting the L* part of a LAB image in
+ * way suitable for print work, but you can use it for other things too.
+ *
+ * The curve is an unsigned 16-bit image with (@in_max + 1) entries, 
+ * each in the range [0, @out_max].
+ *
+ * @Lb, @Lw are expressed as 0-100, as in LAB colour space. You 
+ * specify the scaling for the input and output images with the @in_max and 
+ * @out_max parameters.
+ *
+ * See also: vips_tone_map(), vips_tone_analyse().
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int
+vips_tonelut( VipsImage **out, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, out );
+	result = vips_call_split( "tonelut", ap, out );
+	va_end( ap );
+
+	return( result );
+}
+
diff --git a/libvips/deprecated/vips7compat.c b/libvips/deprecated/vips7compat.c
index 4251a799..3fc527f9 100644
--- a/libvips/deprecated/vips7compat.c
+++ b/libvips/deprecated/vips7compat.c
@@ -2575,6 +2575,54 @@ im_invertlut( DOUBLEMASK *input, VipsImage *out, int size )
 	return( 0 );
 }
 
+int 
+im_tone_build_range( IMAGE *out, 
+	int in_max, int out_max,
+	double Lb, double Lw,
+	double Ps, double Pm, double Ph, 
+	double S, double M, double H )
+{
+	VipsImage *t;
+
+	if( vips_tonelut( &t, 
+		"in_max", in_max,
+		"out_max", out_max,
+		"Lb", Lb,
+		"Lw", Lw,
+		"Ps", Ps,
+		"Pm", Pm,
+		"Ph", Ph,
+		"S", S,
+		"M", M,
+		"H", H,
+		NULL ) )
+		return( -1 );
+	if( vips_image_write( t, out ) ) {
+		g_object_unref( t );
+		return( -1 );
+	}
+	g_object_unref( t );
+
+	return( 0 );
+}
+
+int 
+im_tone_build( IMAGE *out, 
+	double Lb, double Lw,
+	double Ps, double Pm, double Ph, 
+	double S, double M, double H )
+{
+	IMAGE *t1;
+
+	if( !(t1 = im_open_local( out, "im_tone_build", "p" )) ||
+		im_tone_build_range( t1, 32767, 32767,
+			Lb, Lw, Ps, Pm, Ph, S, M, H ) ||
+		im_clip2fmt( t1, out, IM_BANDFMT_SHORT ) )
+		return( -1 );
+
+	return( 0 );
+}
+
 int
 im_rightshift_size( IMAGE *in, IMAGE *out, 
 	int xshift, int yshift, int band_fmt )
diff --git a/libvips/foreign/webpload.c b/libvips/foreign/webpload.c
index d29314f2..609e541d 100644
--- a/libvips/foreign/webpload.c
+++ b/libvips/foreign/webpload.c
@@ -66,8 +66,6 @@ vips_foreign_load_webp_get_flags( VipsForeignLoad *load )
 static int
 vips_foreign_load_webp_build( VipsObject *object )
 {
-	VipsForeignLoadWebp *webp = (VipsForeignLoadWebp *) object;
-
 	if( VIPS_OBJECT_CLASS( vips_foreign_load_webp_parent_class )->
 		build( object ) )
 		return( -1 );
@@ -127,7 +125,6 @@ vips_foreign_load_webp_file_is_a( const char *filename )
 static int
 vips_foreign_load_webp_file_header( VipsForeignLoad *load )
 {
-	VipsForeignLoadWebp *webp = (VipsForeignLoadWebp *) load;
 	VipsForeignLoadWebpFile *file = (VipsForeignLoadWebpFile *) load;
 
 	if( vips__webp_read_file_header( file->filename, load->out ) )
@@ -139,7 +136,6 @@ vips_foreign_load_webp_file_header( VipsForeignLoad *load )
 static int
 vips_foreign_load_webp_file_load( VipsForeignLoad *load )
 {
-	VipsForeignLoadWebp *webp = (VipsForeignLoadWebp *) load;
 	VipsForeignLoadWebpFile *file = (VipsForeignLoadWebpFile *) load;
 
 	if( vips__webp_read_file( file->filename, load->real ) )
@@ -202,7 +198,6 @@ G_DEFINE_TYPE( VipsForeignLoadWebpBuffer, vips_foreign_load_webp_buffer,
 static int
 vips_foreign_load_webp_buffer_header( VipsForeignLoad *load )
 {
-	VipsForeignLoadWebp *webp = (VipsForeignLoadWebp *) load;
 	VipsForeignLoadWebpBuffer *buffer = (VipsForeignLoadWebpBuffer *) load;
 
 	if( vips__webp_read_buffer_header( buffer->buf->data, 
@@ -215,7 +210,6 @@ vips_foreign_load_webp_buffer_header( VipsForeignLoad *load )
 static int
 vips_foreign_load_webp_buffer_load( VipsForeignLoad *load )
 {
-	VipsForeignLoadWebp *webp = (VipsForeignLoadWebp *) load;
 	VipsForeignLoadWebpBuffer *buffer = (VipsForeignLoadWebpBuffer *) load;
 
 	if( vips__webp_read_buffer( buffer->buf->data, buffer->buf->length, 
diff --git a/libvips/histogram/hist_cum.c b/libvips/histogram/hist_cum.c
index 9a4ec629..7a3836bf 100644
--- a/libvips/histogram/hist_cum.c
+++ b/libvips/histogram/hist_cum.c
@@ -159,6 +159,7 @@ vips_hist_cum_init( VipsHistCum *hist_cum )
  * vips_hist_cum:
  * @in: input image
  * @out: output image
+ * @...: %NULL-terminated list of optional named arguments
  *
  * Form cumulative histogram. 
  *
diff --git a/libvips/histogram/hist_equal.c b/libvips/histogram/hist_equal.c
index a6cfd683..9c380c54 100644
--- a/libvips/histogram/hist_equal.c
+++ b/libvips/histogram/hist_equal.c
@@ -134,6 +134,7 @@ vips_hist_equal_init( VipsHistEqual *equal )
  * vips_hist_equal:
  * @in: input image
  * @out: output image
+ * @...: %NULL-terminated list of optional named arguments
  *
  * Optional arguments:
  *
diff --git a/libvips/histogram/hist_norm.c b/libvips/histogram/hist_norm.c
index c74cd993..3baf5c64 100644
--- a/libvips/histogram/hist_norm.c
+++ b/libvips/histogram/hist_norm.c
@@ -159,7 +159,8 @@ vips_hist_norm_init( VipsHistNorm *hist_norm )
  * vips_hist_norm:
  * @in: input image
  * @out: output image
- *
+ * @...: %NULL-terminated list of optional named arguments
+ * 
  * Normalise histogram ... normalise range to make it square (ie. max ==
  * number of elements). Normalise each band separately.
  *
diff --git a/libvips/histogram/hist_percent.c b/libvips/histogram/hist_percent.c
new file mode 100644
index 00000000..b55b5603
--- /dev/null
+++ b/libvips/histogram/hist_percent.c
@@ -0,0 +1,166 @@
+/* find percent of pixels
+ *
+ * Copyright: 1990, N. Dessipris
+ *
+ * Author: N. Dessipris
+ * Written on: 02/08/1990
+ * Modified on : 29/4/93 K.Martinez   for Sys5
+ * 20/2/95 JC
+ *	- now returns result through parameter
+ *	- ANSIfied a little
+ * 19/1/07
+ * 	- redone with the vips hist operators
+ * 25/3/10
+ * 	- gtkdoc
+ * 20/9/13
+ * 	- wrap as a class
+ */
+
+/*
+
+    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., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <stdio.h>
+#include <string.h>
+
+#include <vips/vips.h>
+
+typedef struct _VipsHistPercent { 
+	VipsOperation parent_instance;
+
+	VipsImage *in;
+	double percent;
+	int threshold;
+
+} VipsHistPercent;
+
+typedef VipsOperationClass VipsHistPercentClass;
+
+G_DEFINE_TYPE( VipsHistPercent, vips_hist_percent, VIPS_TYPE_OPERATION );
+
+static int
+vips_hist_percent_build( VipsObject *object )
+{
+	VipsHistPercent *percent = (VipsHistPercent *) object; 
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 6 );
+
+	double threshold;
+
+	if( VIPS_OBJECT_CLASS( vips_hist_percent_parent_class )->
+		build( object ) )
+		return( -1 );
+
+	if( vips_hist_find( percent->in, &t[0], NULL ) ||
+		vips_hist_cum( t[0], &t[1], NULL ) ||
+		vips_hist_norm( t[1], &t[2], NULL ) ||
+		vips_less_const1( t[2], &t[3], 
+			percent->percent * t[2]->Xsize, NULL ) ||
+		vips_flip( t[3], &t[4], VIPS_DIRECTION_HORIZONTAL, NULL ) ||
+		im_profile( t[4], &t[5], 1 ) ||
+		vips_avg( t[5], &threshold ) ) 
+		return( -1 );
+
+	percent->threshold = threshold;
+
+	return( 0 );
+}
+
+static void
+vips_hist_percent_class_init( VipsHistPercentClass *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_percent";
+	object_class->description = _( "find threshold for percent of pixels" );
+	object_class->build = vips_hist_percent_build;
+
+	VIPS_ARG_IMAGE( class, "in", 1, 
+		_( "Input" ), 
+		_( "Input image" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT,
+		G_STRUCT_OFFSET( VipsHistPercent, in ) );
+
+	VIPS_ARG_DOUBLE( class, "percent", 2, 
+		_( "Percent" ), 
+		_( "percent of pixels" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT, 
+		G_STRUCT_OFFSET( VipsHistPercent, percent ),
+		0, 100, 50 );
+
+	VIPS_ARG_INT( class, "threshold", 2, 
+		_( "threshold" ), 
+		_( "threshold above which lie percent of pixels" ),
+		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
+		G_STRUCT_OFFSET( VipsHistPercent, threshold ),
+		0, 65535, 0 );
+
+}
+
+static void
+vips_hist_percent_init( VipsHistPercent *percent )
+{
+}
+
+/**
+ * vips_percent:
+ * @in: input image
+ * @percent: threshold percentage
+ * @threshold: output threshold value
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * vips_percent() returns (through the @threshold parameter) the threshold 
+ * above which there are @percent values of @in. If for example percent=.1, the
+ * number of pels of the input image with values greater than @threshold
+ * will correspond to 10% of all pels of the image.
+ *
+ * The function works for uchar and ushort images only.  It can be used 
+ * to threshold the scaled result of a filtering operation.
+ *
+ * See also: vips_hist_find(), vips_profile().
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int 
+vips_hist_percent( VipsImage *in, double percent, int *threshold, ... )
+{
+	va_list ap;
+	int result;
+
+	va_start( ap, threshold );
+	result = vips_call_split( "hist_percent", ap, in, percent, threshold );
+	va_end( ap );
+
+	return( result );
+}
diff --git a/libvips/histogram/hist_plot.c b/libvips/histogram/hist_plot.c
index 7b52e9fe..eb6c34e3 100644
--- a/libvips/histogram/hist_plot.c
+++ b/libvips/histogram/hist_plot.c
@@ -360,6 +360,7 @@ vips_hist_plot_init( VipsHistPlot *hist_plot )
  * vips_hist_plot:
  * @in: input image
  * @out: output image
+ * @...: %NULL-terminated list of optional named arguments
  *
  * Plot a 1 by any or any by 1 image file as a max by any or 
  * any by max image using these rules:
diff --git a/libvips/histogram/stdif.c b/libvips/histogram/stdif.c
index 3765f427..b64052c8 100644
--- a/libvips/histogram/stdif.c
+++ b/libvips/histogram/stdif.c
@@ -361,6 +361,7 @@ vips_stdif_init( VipsStdif *stdif )
  * @out: output image
  * @width: width of region
  * @height: height of region
+ * @...: %NULL-terminated list of optional named arguments
  *
  * Optional arguments:
  *
diff --git a/libvips/histogram/tone.c b/libvips/histogram/tone.c
index 1ac3539d..410fd2b0 100644
--- a/libvips/histogram/tone.c
+++ b/libvips/histogram/tone.c
@@ -53,266 +53,6 @@
 
 #include <vips/vips.h>
 
-/* Parameters for tone curve formation.
- */
-typedef struct {
-	/* Parameters.
-	 */
-	double Lb, Lw;
-	double Ps, Pm, Ph; 
-	double S, M, H;
-
-	/* Derived values.
-	 */
-	double Ls, Lm, Lh;
-} ToneShape;
-
-/* Calculate shadow curve.
- */
-static double
-shad( ToneShape *ts, double x )
-{
-	double x1 = (x - ts->Lb) / (ts->Ls - ts->Lb);
-	double x2 = (x - ts->Ls) / (ts->Lm - ts->Ls);
-	double out;
-
-	if( x < ts->Lb )
-		out = 0;
-	else if( x < ts->Ls )
-		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
-	else if( x < ts->Lm )
-		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
-	else 
-		out = 0;
-
-	return( out );
-}
-
-/* Calculate mid-tone curve.
- */
-static double
-mid( ToneShape *ts, double x )
-{
-	double x1 = (x - ts->Ls) / (ts->Lm - ts->Ls);
-	double x2 = (x - ts->Lm) / (ts->Lh - ts->Lm);
-	double out;
-
-	if( x < ts->Ls )
-		out = 0;
-	else if( x < ts->Lm )
-		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
-	else if( x < ts->Lh )
-		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
-	else 
-		out = 0;
-
-	return( out );
-}
-
-/* Calculate highlight curve.
- */
-static double
-high( ToneShape *ts, double x )
-{
-	double x1 = (x - ts->Lm) / (ts->Lh - ts->Lm);
-	double x2 = (x - ts->Lh) / (ts->Lw - ts->Lh);
-	double out;
-
-	if( x < ts->Lm )
-		out = 0;
-	else if( x < ts->Lh )
-		out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
-	else if( x < ts->Lw )
-		out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
-	else 
-		out = 0;
-
-	return( out );
-}
-
-/* Generate a point on the tone curve. Everything is 0-100.
- */
-static double
-tone_curve( ToneShape *ts, double x )
-{
-	double out;
-
-	out = x + 
-		ts->S * shad( ts, x ) + ts->M * mid( ts, x ) + 
-		ts->H * high( ts, x );
-	
-	return( out );
-}
-
-/**
- * im_tone_build_range:
- * @out: output image 
- * @in_max: input range 
- * @out_max: output range
- * @Lb: black-point [0-100]
- * @Lw: white-point [0-100]
- * @Ps: shadow point (eg. 0.2)
- * @Pm: mid-tone point (eg. 0.5)
- * @Ph: highlight point (eg. 0.8)
- * @S: shadow adjustment (+/- 30)
- * @M: mid-tone adjustment (+/- 30)
- * @H: highlight adjustment (+/- 30)
- *
- * im_tone_build_range() generates a tone curve for the adjustment of image 
- * levels. It is mostly designed for adjusting the L* part of a LAB image in
- * way suitable for print work, but you can use it for other things too.
- *
- * The curve is an unsigned 16-bit image with (@in_max + 1) entries, 
- * each in the range [0, @out_max].
- *
- * @Lb, @Lw are expressed as 0-100, as in LAB colour space. You 
- * specify the scaling for the input and output images with the @in_max and 
- * @out_max parameters.
- *
- * See also: im_ismonotonic(), im_tone_map(), im_tone_analyse().
- *
- * Returns: 0 on success, -1 on error
- */
-int 
-im_tone_build_range( IMAGE *out, 
-	int in_max, int out_max,
-	double Lb, double Lw,
-	double Ps, double Pm, double Ph, 
-	double S, double M, double H )
-{
-	ToneShape *ts;
-	unsigned short lut[65536];
-	int i;
-
-	/* Check args.
-	 */
-	if( !(ts = IM_NEW( out, ToneShape )) ||
-		im_outcheck( out ) )
-		return( -1 );
-	if( in_max < 0 || in_max > 65535 ||
-		out_max < 0 || out_max > 65535 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "bad in_max, out_max parameters" ) );
-		return( -1 );
-	}
-	if( Lb < 0 || Lb > 100 || Lw < 0 || Lw > 100 || Lb > Lw ) {
-		im_error( "im_tone_build", 
-			"%s", _( "bad Lb, Lw parameters" ) );
-		return( -1 );
-	}
-	if( Ps < 0.0 || Ps > 1.0 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "Ps not in range [0.0,1.0]" ) );
-		return( -1 );
-	}
-	if( Pm < 0.0 || Pm > 1.0 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "Pm not in range [0.0,1.0]" ) );
-		return( -1 );
-	}
-	if( Ph < 0.0 || Ph > 1.0 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "Ph not in range [0.0,1.0]" ) );
-		return( -1 );
-	}
-	if( S < -30 || S > 30 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "S not in range [-30,+30]" ) );
-		return( -1 );
-	}
-	if( M < -30 || M > 30 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "M not in range [-30,+30]" ) );
-		return( -1 );
-	}
-	if( H < -30 || H > 30 ) {
-		im_error( "im_tone_build", 
-			"%s", _( "H not in range [-30,+30]" ) );
-		return( -1 );
-	}
-
-	/* Note params.
-	 */
-	ts->Lb = Lb; 
-	ts->Lw = Lw;
-	ts->Ps = Ps; 
-	ts->Pm = Pm; 
-	ts->Ph = Ph;
-	ts->S = S; 
-	ts->M = M; 
-	ts->H = H;
-
-	/* Note derived params.
-	 */
-	ts->Ls = Lb + Ps * (Lw - Lb);
-	ts->Lm = Lb + Pm * (Lw - Lb);
-	ts->Lh = Lb + Ph * (Lw - Lb);
-
-	/* Generate curve.
-	 */
-	for( i = 0; i <= in_max; i++ ) {
-		int v = (out_max / 100.0) * 
-			tone_curve( ts, 100.0 * i / in_max );
-
-		if( v < 0 )
-			v = 0;
-		else if( v > out_max )
-			v = out_max;
-		
-		lut[i] = v;
-	}
-
-	/* Make the output image.
-	 */
-	im_initdesc( out,
-		in_max + 1, 1, 1, IM_BBITS_SHORT, IM_BANDFMT_USHORT, 
-		IM_CODING_NONE, IM_TYPE_HISTOGRAM, 1.0, 1.0, 0, 0 );
-	if( im_setupout( out ) )
-		return( -1 );
-
-	if( im_writeline( 0, out, (VipsPel *) lut ) )
-		return( -1 );
-
-	return( 0 );
-}
-
-/**
- * im_tone_build:
- * @out: output image 
- * @Lb: black-point [0-100]
- * @Lw: white-point [0-100]
- * @Ps: shadow point (eg. 0.2)
- * @Pm: mid-tone point (eg. 0.5)
- * @Ph: highlight point (eg. 0.8)
- * @S: shadow adjustment (+/- 30)
- * @M: mid-tone adjustment (+/- 30)
- * @H: highlight adjustment (+/- 30)
- *
- * As im_tone_build_range(), but set 32767 and 32767 as values for @in_max 
- * and @out_max. This makes a curve suitable for correcting LABS
- * images, the most common case.
- *
- * See also: im_tone_build_range().
- *
- * Returns: 0 on success, -1 on error
- */
-int 
-im_tone_build( IMAGE *out, 
-	double Lb, double Lw,
-	double Ps, double Pm, double Ph, 
-	double S, double M, double H )
-{
-	IMAGE *t1;
-
-	if( !(t1 = im_open_local( out, "im_tone_build", "p" )) ||
-		im_tone_build_range( t1, 32767, 32767,
-			Lb, Lw, Ps, Pm, Ph, S, M, H ) ||
-		im_clip2fmt( t1, out, IM_BANDFMT_SHORT ) )
-		return( -1 );
-
-	return( 0 );
-}
-
 /**
  * im_ismonotonic:
  * @lut: lookup-table to test
diff --git a/libvips/include/vips/create.h b/libvips/include/vips/create.h
index 3f0f6bdf..abaa7167 100644
--- a/libvips/include/vips/create.h
+++ b/libvips/include/vips/create.h
@@ -66,6 +66,8 @@ int vips_buildlut( VipsImage *in, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_invertlut( VipsImage *in, VipsImage **out, ... )
 	__attribute__((sentinel));
+int vips_tonelut( VipsImage **out, ... )
+	__attribute__((sentinel));
 
 int im_benchmarkn( VipsImage *in, VipsImage *out, int n );
 int im_benchmark2( VipsImage *in, double *out );
diff --git a/libvips/include/vips/histogram.h b/libvips/include/vips/histogram.h
index bc5fb123..b0e92009 100644
--- a/libvips/include/vips/histogram.h
+++ b/libvips/include/vips/histogram.h
@@ -61,13 +61,6 @@ int im_ismonotonic( VipsImage *lut, int *out );
 int im_mpercent( VipsImage *in, double percent, int *out );
 int im_mpercent_hist( VipsImage *hist, double percent, int *out );
 
-int im_tone_build_range( VipsImage *out,
-	int in_max, int out_max,
-	double Lb, double Lw, double Ps, double Pm, double Ph,
-	double S, double M, double H );
-int im_tone_build( VipsImage *out,
-	double Lb, double Lw, double Ps, double Pm, double Ph,
-	double S, double M, double H );
 int im_tone_analyse( VipsImage *in, VipsImage *out,
 	double Ps, double Pm, double Ph, double S, double M, double H );
 int im_tone_map( VipsImage *in, VipsImage *out, VipsImage *lut );
diff --git a/libvips/include/vips/vips7compat.h b/libvips/include/vips/vips7compat.h
index 0194b0e8..04774bfe 100644
--- a/libvips/include/vips/vips7compat.h
+++ b/libvips/include/vips/vips7compat.h
@@ -739,6 +739,14 @@ int im_invertlut( DOUBLEMASK *input, VipsImage *output, int lut_size );
 int im_identity( VipsImage *lut, int bands );
 int im_identity_ushort( VipsImage *lut, int bands, int sz );
 
+int im_tone_build_range( VipsImage *out,
+	int in_max, int out_max,
+	double Lb, double Lw, double Ps, double Pm, double Ph,
+	double S, double M, double H );
+int im_tone_build( VipsImage *out,
+	double Lb, double Lw, double Ps, double Pm, double Ph,
+	double S, double M, double H );
+
 int im_system( VipsImage *im, const char *cmd, char **out );
 VipsImage *im_system_image( VipsImage *im, 
 	const char *in_format, const char *out_format, const char *cmd_format,