diff --git a/libvips/conversion/im_msb.c b/libvips/conversion/im_msb.c
index 1258f49c..017d6f4e 100644
--- a/libvips/conversion/im_msb.c
+++ b/libvips/conversion/im_msb.c
@@ -1,21 +1,4 @@
-/* @(#) Convert a signed or unsigned, char or short or int image into unsigned
- * @(#) char very quickly, by discarding the lower order bits.  Signed values
- * @(#) are converted to unsigned by adding 128.
- * @(#)
- * @(#) int
- * @(#) im_msb(
- * @(#)   IMAGE *in,
- * @(#)   IMAGE *out
- * @(#) );
- * @(#)
- * @(#) As above, but also discard all but the specified band:
- * @(#)
- * @(#) int
- * @(#) im_msb(
- * @(#)   IMAGE *in,
- * @(#)   IMAGE *out,
- * @(#)   int band
- * @(#) );
+/* im_msb
  *
  * Copyright: 2006, The Nottingham Trent University
  *
@@ -27,6 +10,9 @@
  * 4/10/06
  * 	- removed warning on uchar fallback: it happens a lot with nip2 and
  * 	  isn't very serious
+ * 1/2/10
+ * 	- revised, cleanups
+ * 	- gtkdoc
  */
 
 /*
@@ -62,283 +48,181 @@
 #endif /*HAVE_CONFIG_H */
 #include <vips/intl.h>
 
-#include <stdlib.h>
-
 #include <vips/vips.h>
 
 #ifdef WITH_DMALLOC
 #include <dmalloc.h>
 #endif /*WITH_DMALLOC */
 
-/** MACROS **/
-/* BAND FORMAT TESTS */
+typedef struct _Msb {
+	size_t index;
+	size_t width;
+	size_t repeat;
+} Msb;
 
-#define SIZEOF_BAND(band_fmt) (                                       \
-     ( IM_BANDFMT_UCHAR == (band_fmt) ) ? sizeof(unsigned char)       \
- :   ( IM_BANDFMT_CHAR  == (band_fmt) ) ? sizeof(signed char)         \
- :  ( IM_BANDFMT_USHORT == (band_fmt) ) ? sizeof(unsigned short int)  \
- :   ( IM_BANDFMT_SHORT == (band_fmt) ) ? sizeof(signed short int)    \
- :    ( IM_BANDFMT_UINT == (band_fmt) ) ? sizeof(unsigned int)        \
- :     ( IM_BANDFMT_INT == (band_fmt) ) ? sizeof(signed int)          \
- :   ( IM_BANDFMT_FLOAT == (band_fmt) ) ? sizeof(float)               \
- :  ( IM_BANDFMT_DOUBLE == (band_fmt) ) ? sizeof(double)              \
- : ( IM_BANDFMT_COMPLEX == (band_fmt) ) ? ( 2 * sizeof(float) )       \
- :                                        ( 2 * sizeof(double) ) )
+static void
+byte_select( unsigned char *in, unsigned char *out, int n, Msb *msb )
+{
+	unsigned char *stop = out + n * msb->repeat;
 
-#define BANDFMT_SHORT_CHAR(band_fmt)  (  \
-       IM_BANDFMT_SHORT == (band_fmt)    \
-  ||  IM_BANDFMT_USHORT == (band_fmt)    \
-  ||    IM_BANDFMT_CHAR == (band_fmt)    \
-  ||   IM_BANDFMT_UCHAR == (band_fmt) )
+	for( in += msb->index; out < stop; in += msb->width, ++out )
+		*out = *in;
+}
 
-#define BANDFMT_ANY_INT(band_fmt)    (  \
-         IM_BANDFMT_INT == (band_fmt)   \
-  ||    IM_BANDFMT_UINT == (band_fmt)   \
-  ||     BANDFMT_SHORT_CHAR(band_fmt) )
+static void
+byte_select_flip( unsigned char *in, unsigned char *out, int n, Msb *msb )
+{
+	unsigned char *stop = out + n * msb->repeat;
 
-#define BANDFMT_UNSIGNED(band_fmt)  (   \
-        IM_BANDFMT_UINT == (band_fmt)   \
-  ||  IM_BANDFMT_USHORT == (band_fmt)   \
-  ||   IM_BANDFMT_UCHAR == (band_fmt) )
+	for( in += msb->index; out < stop; in += msb->width, ++out )
+		*out = 0x80 ^ *in;
+}
 
-/* IMAGE TESTS */
+static void
+msb_labq( unsigned char *in, unsigned char *out, int n )
+{
+	unsigned char *stop = in + (n << 2);
 
-#define IM_ANY_INT(im)      BANDFMT_ANY_INT((im)-> BandFmt)
-#define IM_UNSIGNED(im)     BANDFMT_UNSIGNED((im)-> BandFmt)
-#define IM_UNCODED(im)      ( IM_CODING_NONE == (im)-> Coding )
-
-/** LOCAL FUNCTIONS DECLARATIONS **/
-static void byte_select (unsigned char *in, unsigned char *out, int n,
-			 size_t * params);
-static void byte_select_flip (unsigned char *in, unsigned char *out, int n,
-			      size_t * params);
-static void msb_labq (unsigned char *in, unsigned char *out, int n);
-
-/** EXPORTED FUNCTIONS **/
+	for( ; in < stop; in += 4, out += 3 ) {
+		out[0] = in[0];
+		out[1] = 0x80 ^ in[1];
+		out[2] = 0x80 ^ in[2];
+	}
+}
 
+/**
+ * im_msb:
+ * @in: input image
+ * @out: output image
+ *
+ * Turn any integer image to 8-bit unsigned char by discarding all but the most
+ * significant byte.
+ * Signed values are converted to unsigned by adding 128.
+ *
+ * This operator also works for LABQ coding.
+ *
+ * See also: im_msb_band().
+ *
+ * Returns: 0 on success, -1 on error
+ */
 int
-im_msb (IMAGE * in, IMAGE * out)
+im_msb( IMAGE *in, IMAGE *out )
 {
-#define FUNCTION_NAME "im_msb"
+	Msb *msb;
+	im_wrapone_fn func;
 
-  size_t *params;
-  im_wrapone_fn func;
+	if( in->Coding == IM_CODING_NONE &&
+		in->BandFmt == IM_BANDFMT_UCHAR )
+		return( im_copy( in, out ) );
 
-#define index   (params[0])
-#define width   (params[1])
-#define repeat  (params[2])
+	if( im_piocheck( in, out ) ||
+		!(msb = IM_NEW( out, Msb )) )
+		return( -1 );
 
-  if (im_piocheck (in, out))
-    return -1;
+	if( in->Coding == IM_CODING_NONE ) {
+		if( im_check_int( "im_msb", in ) ) 
+			return( -1 );
 
-  /* Stops a used-before-set warning.
-   */
-  params = NULL;
+		msb->width = IM_IMAGE_SIZEOF_ELEMENT( in );
+		msb->index = im_amiMSBfirst() ? 0 : msb->width - 1;
+		msb->repeat = in->Bands;
 
-  if (IM_UNCODED (in))
-    {
-
-      if (!IM_ANY_INT (in))
-	{
-	  im_error (FUNCTION_NAME, "%s", _("char, short or int only"));
-	  return -1;
+		if( vips_bandfmt_isuint( in->BandFmt ) )
+			func = (im_wrapone_fn) byte_select;
+		else
+			func = (im_wrapone_fn) byte_select_flip;
+	}
+	else if( IM_CODING_LABQ == in->Coding )
+		func = (im_wrapone_fn) msb_labq;
+	else {
+		im_error( "im_msb", "%s", _( "unknown coding" ) );
+		return( -1 );
 	}
 
-      params = IM_ARRAY (out, 3, size_t);
+	if( im_cp_desc( out, in ) )
+		return( -1 );
+	out->BandFmt = IM_BANDFMT_UCHAR;
+	out->Coding = IM_CODING_NONE;
 
-      if (!params)
-	return -1;
-
-      width = SIZEOF_BAND (in->BandFmt);
-
-#if G_BYTE_ORDER == G_BIG_ENDIAN
-      index = 0;
-#else
-      index = width - 1;
-#endif
-
-      repeat = in->Bands;
-
-      if (IM_UNSIGNED (in))
-	func = (im_wrapone_fn) byte_select;
-      else
-	func = (im_wrapone_fn) byte_select_flip;
-
-      if (1 == width && (im_wrapone_fn) byte_select == func)
-	{
-	  return im_copy (in, out);
-	}
-    }
-
-  else if (IM_CODING_LABQ == in->Coding)
-
-    func = (im_wrapone_fn) msb_labq;
-
-  else
-    {
-      im_error (FUNCTION_NAME, "%s", _("unknown coding"));
-      return -1;
-    }
-
-  if (im_cp_desc (out, in))
-    return -1;
-
-  out->BandFmt = IM_BANDFMT_UCHAR;
-  out->Coding = IM_CODING_NONE;
-
-  return im_wrapone (in, out, func, (void *) params, NULL);
-
-#undef index
-#undef width
-#undef repeat
-
-#undef FUNCTION_NAME
+	return( im_wrapone( in, out, func, msb, NULL ) );
 }
 
+/**
+ * im_msb_band:
+ * @in: input image
+ * @out: output image
+ * @band: select this band
+ *
+ * Turn any integer image to a single-band 8-bit unsigned char by discarding 
+ * all but the most significant byte from the selected band. 
+ * Signed values are converted to unsigned by adding 128.
+ *
+ * This operator also works for LABQ coding.
+ *
+ * See also: im_msb_band().
+ *
+ * Returns: 0 on success, -1 on error
+ */
 int
-im_msb_band (IMAGE * in, IMAGE * out, int band)
+im_msb_band( IMAGE *in, IMAGE *out, int band )
 {
-#define FUNCTION_NAME "im_msb_band"
+	Msb *msb;
+	im_wrapone_fn func;
 
-  size_t *params;
-  im_wrapone_fn func;
-
-#define index   (params[0])
-#define width   (params[1])
-#define repeat  (params[2])
-
-  if (band < 0)
-    {
-      im_error (FUNCTION_NAME, "%s", _("bad arguments"));
-      return -1;
-    }
-
-  if (im_piocheck (in, out))
-    return -1;
-
-  params = IM_ARRAY (out, 3, size_t);
-
-  if (!params)
-    return -1;
-
-  if (IM_UNCODED (in))
-    {
-
-      if (!IM_ANY_INT (in))
-	{
-	  im_error (FUNCTION_NAME, "%s", _("char, short or int only"));
-	  return -1;
+	if( band < 0 ) {
+		im_error( "im_msb_band", "%s", _( "bad arguments" ) );
+		return( -1 );
 	}
 
-      if (band >= in->Bands)
-	{
-	  im_error (FUNCTION_NAME,
-	    "%s", _("image does not have that many bands"));
-	  return -1;
+	if( im_piocheck( in, out ) ||
+		!(msb = IM_NEW( out, Msb )) )
+		return( -1 );
+
+	if( in->Coding == IM_CODING_NONE ) {
+		if( im_check_int( "im_msb_band", in ) ) 
+			return( -1 );
+
+		if( band >= in->Bands ) {
+			im_error( "im_msb_band", "%s", 
+				_( "image does not have that many bands" ) );
+			return( -1 );
+		}
+
+		msb->width = IM_IMAGE_SIZEOF_ELEMENT( in );
+		msb->index = im_amiMSBfirst() ? 
+			msb->width * band : msb->width * (band + 1) - 1;
+		msb->repeat = 1;
+
+		if( vips_bandfmt_isuint( in->BandFmt ) )
+			func = (im_wrapone_fn) byte_select;
+		else
+			func = (im_wrapone_fn) byte_select_flip;
+	}
+	else if( IM_CODING_LABQ == in->Coding ) {
+		if( band > 2 ) {
+			im_error( "im_msb_band", "%s", 
+				_( "image does not have that many bands" ) );
+			return( -1 );
+		}
+		msb->width = 4;
+		msb->repeat = 1;
+		msb->index = band;
+
+		if( band )
+			func = (im_wrapone_fn) byte_select_flip;
+		else
+			func = (im_wrapone_fn) byte_select;
+	}
+	else {
+		im_error( "im_msb", "%s", _( "unknown coding" ) );
+		return( -1 );
 	}
 
-      width = SIZEOF_BAND (in->BandFmt);
+	if( im_cp_desc( out, in ) )
+		return( -1 );
+	out->BandFmt = IM_BANDFMT_UCHAR;
+	out->Coding = IM_CODING_NONE;
+	out->Bands = 1;
 
-#if G_BYTE_ORDER == G_BIG_ENDIAN
-      index = width * band;
-#else
-      index = (width * (band + 1)) - 1;
-#endif
-
-      width *= in->Bands;
-      repeat = 1;
-
-      if (IM_UNSIGNED (in))
-	func = (im_wrapone_fn) byte_select;
-      else
-	func = (im_wrapone_fn) byte_select_flip;
-    }
-
-  else if (IM_CODING_LABQ == in->Coding)
-    {
-
-      if (band > 2)
-	{
-	  im_error (FUNCTION_NAME, 
-	    "%s", _("image does not have that many bands"));
-	  return -1;
-	}
-      width = 4;
-      repeat = 1;
-      index = band;
-
-      if (band)
-	func = (im_wrapone_fn) byte_select_flip;
-      else
-	func = (im_wrapone_fn) byte_select;
-    }
-  else
-    {
-      im_error (FUNCTION_NAME, "%s", _("unknown coding"));
-      return -1;
-    }
-
-  if (im_cp_desc (out, in))
-    return -1;
-
-  out->Bands = 1;
-  out->BandFmt = IM_BANDFMT_UCHAR;
-  out->Coding = IM_CODING_NONE;
-
-  return im_wrapone (in, out, func, (void *) params, NULL);
-
-#undef index
-#undef width
-#undef repeat
-
-#undef FUNCTION_NAME
-}
-
-/** LOCAL FUNCTIONS DEFINITIONS **/
-static void
-byte_select (unsigned char *in, unsigned char *out, int n, size_t * params)
-{
-#define index   (params[0])
-#define width   (params[1])
-#define repeat  (params[2])
-
-  unsigned char *stop = out + n * repeat;
-
-  for (in += index; out < stop; in += width, ++out)
-    *out = *in;
-
-#undef index
-#undef width
-#undef repeat
-}
-
-static void
-byte_select_flip (unsigned char *in, unsigned char *out, int n,
-		  size_t * params)
-{
-#define index   (params[0])
-#define width   (params[1])
-#define repeat  (params[2])
-
-  unsigned char *stop = out + n * repeat;
-
-  for (in += index; out < stop; in += width, ++out)
-    *out = 0x80 ^ *in;
-
-#undef index
-#undef width
-#undef repeat
-}
-
-static void
-msb_labq (unsigned char *in, unsigned char *out, int n)
-{
-  unsigned char *stop = in + (n << 2);
-
-  for (; in < stop; in += 4, out += 3)
-    {
-      out[0] = in[0];
-      out[1] = 0x80 ^ in[1];
-      out[2] = 0x80 ^ in[2];
-    }
+	return( im_wrapone( in, out, func, msb, NULL ) );
 }