diff --git a/libvips/histogram/hist_cum.c b/libvips/histogram/hist_cum.c
new file mode 100644
index 00000000..87019aad
--- /dev/null
+++ b/libvips/histogram/hist_cum.c
@@ -0,0 +1,149 @@
+/* histogram cumulativisation
+ *
+ * Author: N. Dessipris
+ * Written on: 02/08/1990
+ * 24/5/95 JC
+ *	- tidied up and ANSIfied
+ * 20/7/95 JC
+ *	- smartened up again
+ *	- now works for hists >256 elements
+ * 3/3/01 JC
+ *	- broken into cum and norm ... helps im_histspec()
+ *	- better behaviour for >8 bit hists
+ * 31/10/05 JC
+ * 	- was broken for vertical histograms, gah
+ * 	- neater im_histnorm()
+ * 23/7/07
+ * 	- eek, off by 1 for more than 1 band hists
+ * 12/5/08
+ * 	- histcum works for signed hists now as well
+ * 24/3/10
+ * 	- gtkdoc
+ * 	- small cleanups
+ * 12/8/13	
+ * 	- redone im_histcum() as a class, vips_hist_cum()
+ */
+
+/*
+
+    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 <vips/vips.h>
+
+#include "phistogram.h"
+
+#define ACCUMULATE( ITYPE, OTYPE ) { \
+	for( b = 0; b < nb; b++ ) { \
+		ITYPE *p = (ITYPE *) in->data; \
+		OTYPE *q = (OTYPE *) outbuf; \
+		OTYPE total; \
+		\
+		total = 0; \
+		for( x = b; x < mx; x += nb ) { \
+			total += p[x]; \
+			q[x] = total; \
+		} \
+	} \
+}
+
+/**
+ * im_histcum:
+ * @in: input image
+ * @out: output image
+ *
+ * Form cumulative histogram. 
+ *
+ * See also: im_histnorm().
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int 
+im_histcum( IMAGE *in, IMAGE *out )
+{
+	const guint64 px = VIPS_IMAGE_N_PELS( in );
+	const int nb = vips_bandfmt_iscomplex( in->BandFmt ) ? 
+		in->Bands * 2 : in->Bands;
+	const guint64 mx = px * nb;
+
+	VipsPel *outbuf;		
+	guint64 b, x;
+
+	if( im_check_uncoded( "im_histcum", in ) ||
+		im_check_hist( "im_histcum", in ) ||
+		im_iocheck( in, out ) )
+		return( -1 );
+
+	if( im_cp_desc( out, in ) )
+		return( -1 );
+	out->Xsize = px;
+	out->Ysize = 1;
+	if( vips_bandfmt_isuint( in->BandFmt ) )
+		out->BandFmt = IM_BANDFMT_UINT;
+	else if( vips_bandfmt_isint( in->BandFmt ) )
+		out->BandFmt = IM_BANDFMT_INT;
+	if( im_setupout( out ) )
+		return( -1 );
+
+	if( !(outbuf = im_malloc( out, IM_IMAGE_SIZEOF_LINE( out ))) )
+                return( -1 );
+
+        switch( in->BandFmt ) {
+        case IM_BANDFMT_CHAR: 		
+		ACCUMULATE( signed char, signed int ); break; 
+        case IM_BANDFMT_UCHAR: 		
+		ACCUMULATE( unsigned char, unsigned int ); break; 
+        case IM_BANDFMT_SHORT: 		
+		ACCUMULATE( signed short, signed int ); break; 
+        case IM_BANDFMT_USHORT: 	
+		ACCUMULATE( unsigned short, unsigned int ); break; 
+        case IM_BANDFMT_INT: 		
+		ACCUMULATE( signed int, signed int ); break; 
+        case IM_BANDFMT_UINT: 		
+		ACCUMULATE( unsigned int, unsigned int ); break; 
+
+        case IM_BANDFMT_FLOAT: 		
+        case IM_BANDFMT_COMPLEX:	
+		ACCUMULATE( float, float ); break;
+        case IM_BANDFMT_DOUBLE:		
+        case IM_BANDFMT_DPCOMPLEX:	
+		ACCUMULATE( double, double ); break;
+
+        default:
+		g_assert( 0 );
+        }
+
+	if( im_writeline( 0, out, outbuf ) )
+		return( -1 );
+
+	return( 0 );
+}