diff --git a/ChangeLog b/ChangeLog
index 1ffb1872..ead3bdb8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,7 @@
 - im_iterate() -> vips_sink()
 - better number-of-bands detection for im_magick2vips() 
 - added im_get_argv0()
+- added PFM read / write
 
 16/1/10 started 7.21.2
 - "invalidate" is careful to keep images alive, so invalidate callbacks can do
diff --git a/TODO b/TODO
index 781a00e1..9c7bcdd6 100644
--- a/TODO
+++ b/TODO
@@ -1,8 +1,9 @@
 
-- add support for PFM files, portable float maps
+- convert_saveable for other writers: tiff, ppm, csv, rad etc.
 
-  used in HDR imaging, apparently
+  the tiff writer could use more im_check_ things
 
+  test pfm write
 
 
 - expose more of the tone funcs in nip2
diff --git a/libvips/conversion/im_copy.c b/libvips/conversion/im_copy.c
index e585ef28..379658a2 100644
--- a/libvips/conversion/im_copy.c
+++ b/libvips/conversion/im_copy.c
@@ -389,16 +389,16 @@ im_copy_native( IMAGE *in, IMAGE *out, gboolean is_msb_first )
 /* Convert to a saveable format. 
  *
  * im__saveable_t gives the general type of image
- * we make: vanilla 1/3 bands (PPM), with an optional alpha (like PNG), or
- * with CMYK as an option (like JPEG). 
+ * we make: vanilla 1/3 bands (eg. PPM), with an optional alpha (eg. PNG), or
+ * with CMYK as an option (eg. JPEG). 
  *
- * sixteen TRUE means 16 bit uchar is OK as well (eg. PNG), otherwise we
- * always cast down to u8.
+ * format_table[] says how to convert each input format. 
  *
  * Need to im_close() the result IMAGE.
  */
 IMAGE *
-im__convert_saveable( IMAGE *in, im__saveable_t saveable, gboolean sixteen )
+im__convert_saveable( IMAGE *in, 
+	im__saveable_t saveable, int format_table[10] ) 
 {
 	IMAGE *out;
 
@@ -476,6 +476,9 @@ im__convert_saveable( IMAGE *in, im__saveable_t saveable, gboolean sixteen )
 
 			in = t;
 		}
+
+		/* Else we have saveable IM__ANY and we don't chop bands down.
+		 */
 	}
 
 	/* Interpret the Type field for colorimetric images.
@@ -573,18 +576,12 @@ im__convert_saveable( IMAGE *in, im__saveable_t saveable, gboolean sixteen )
 		in = t[1];
 	}
 
-	/* Clip to uchar/ushort if not there already. 
+	/* Cast to the output format.
 	 */
-	if(     (sixteen && 
-		in->BandFmt != IM_BANDFMT_UCHAR && 
-		in->BandFmt != IM_BANDFMT_USHORT) ||
-		(!sixteen && 
-		 in->BandFmt != IM_BANDFMT_UCHAR) ) {
+	{
 		IMAGE *t = im_open_local( out, "conv:1", "p" );
-		VipsBandFmt fmt = sixteen && IM_IMAGE_SIZEOF_ELEMENT( in ) > 1 ?
-			IM_BANDFMT_USHORT : IM_BANDFMT_UCHAR;
 
-		if( !t || im_clip2fmt( in, t, fmt ) ) {
+		if( !t || im_clip2fmt( in, t, format_table[in->BandFmt] ) ) {
 			im_close( out );
 			return( NULL );
 		}
@@ -599,4 +596,3 @@ im__convert_saveable( IMAGE *in, im__saveable_t saveable, gboolean sixteen )
 
 	return( out );
 }
-
diff --git a/libvips/format/im_magick2vips.c b/libvips/format/im_magick2vips.c
index c289f4db..8d386163 100644
--- a/libvips/format/im_magick2vips.c
+++ b/libvips/format/im_magick2vips.c
@@ -367,9 +367,8 @@ parse_header( Read *read )
 	ResetImagePropertyIterator( image );
 	while( (key = GetNextImageProperty( image )) ) {
 		char name_text[256];
-		VipsBuf name;
+		VipsBuf name = VIPS_BUF_STATIC( name_text );
 
-		vips_buf_init_static( &name, name_text, 256 );
 		vips_buf_appendf( &name, "magick-%s", key );
 		im_meta_set_string( im, 
 			vips_buf_all( &name ), GetImageProperty( image, key ) );
@@ -384,9 +383,8 @@ parse_header( Read *read )
 	ResetImageAttributeIterator( image );
 	while( (attr = GetNextImageAttribute( image )) ) {
 		char name_text[256];
-		VipsBuf name;
+		VipsBuf name = VIPS_BUF_STATIC( name_text );
 
-		vips_buf_init_static( &name, name_text, 256 );
 		vips_buf_appendf( &name, "magick-%s", attr->key );
 		im_meta_set_string( im, vips_buf_all( &name ), attr->value );
 	}
@@ -401,9 +399,8 @@ parse_header( Read *read )
 	 */
 	for( attr = image->attributes; attr; attr = attr->next ) {
 		char name_text[256];
-		VipsBuf name;
+		VipsBuf name = VIPS_BUF_STATIC( name_text );
 
-		vips_buf_init_static( &name, name_text, 256 );
 		vips_buf_appendf( &name, "magick-%s", attr->key );
 		im_meta_set_string( im, vips_buf_all( &name ), attr->value );
 	}
diff --git a/libvips/format/im_ppm2vips.c b/libvips/format/im_ppm2vips.c
index ba59a564..ae61e985 100644
--- a/libvips/format/im_ppm2vips.c
+++ b/libvips/format/im_ppm2vips.c
@@ -21,6 +21,8 @@
  * 	- tiny cleanups
  * 4/2/10
  * 	- gtkdoc
+ * 1/5/10
+ * 	- add PFM (portable float map) support
  */
 
 /*
@@ -56,9 +58,9 @@
 
 #include <ctype.h>
 #include <stdio.h>
-#include <assert.h>
 #include <string.h>
 #include <stdlib.h>
+#include <math.h>
 
 #include <vips/vips.h>
 #include <vips/internal.h>
@@ -96,39 +98,35 @@ skip_white_space( FILE *fp )
 }
 
 static int
-read_uint( FILE *fp )
+read_int( FILE *fp, int *i )
 {
-	int i;
-	char buf[IM_MAX_THING];
-	int ch;
-
 	skip_white_space( fp );
-
-	/* Stop complaints about used-before-set on ch.
-	 */
-	ch = -1;
-
-	for( i = 0; i < IM_MAX_THING - 1 && isdigit( ch = fgetc( fp ) ); i++ ) 
-		buf[i] = ch;
-	buf[i] = '\0';
-
-	if( i == 0 ) {
-		im_error( "im_ppm2vips", "%s", _( "bad unsigned int" ) );
+	if( fscanf( fp, "%d", i ) != 1 ) {
+		im_error( "im_ppm2vips", "%s", _( "bad int" ) );
 		return( -1 );
 	}
 
-	ungetc( ch, fp );
-
-	return( atoi( buf ) );
+	return( 0 );
 }
 
 static int
-read_header( FILE *fp, IMAGE *out, int *bits, int *ascii )
+read_float( FILE *fp, float *f )
+{
+	skip_white_space( fp );
+	if( fscanf( fp, "%f", f ) != 1 ) {
+		im_error( "im_ppm2vips", "%s", _( "bad float" ) );
+		return( -1 );
+	}
+
+	return( 0 );
+}
+
+static int
+read_header( FILE *fp, IMAGE *out, int *bits, int *ascii, int *msb_first )
 {
 	int width, height, bands, fmt, type;
-	int i;
+	int index;
 	char buf[IM_MAX_THING];
-	int max_value;
 
 	/* ppm types.
 	 */
@@ -138,19 +136,21 @@ read_header( FILE *fp, IMAGE *out, int *bits, int *ascii )
 		"P3",	/* ppm ... 3 band many bit, ascii */
 		"P4",	/* pbm ... 1 band 1 bit, binary */
 		"P5",	/* pgm ... 1 band 8 bit, binary */
-		"P6"	/* ppm ... 3 band 8 bit, binary */
+		"P6",	/* ppm ... 3 band 8 bit, binary */
+		"PF",	/* pfm ... 3 band 32 bit, binary */
+		"Pf"	/* pfm ... 1 band 32 bit, binary */
 	};
 
 	/* Characteristics, indexed by ppm type.
 	 */
 	static int lookup_bits[] = {
-		1, 8, 8, 1, 8, 8
+		1, 8, 8, 1, 8, 8, 32, 32
 	};
 	static int lookup_bands[] = {
-		1, 1, 3, 1, 1, 3
+		1, 1, 3, 1, 1, 3, 3, 1
 	};
 	static int lookup_ascii[] = {
-		1, 1, 1, 0, 0, 0
+		1, 1, 1, 0, 0, 0, 0, 0
 	};
 
 	/* Read in the magic number.
@@ -159,33 +159,52 @@ read_header( FILE *fp, IMAGE *out, int *bits, int *ascii )
 	buf[1] = fgetc( fp );
 	buf[2] = '\0';
 
-	for( i = 0; i < IM_NUMBER( magic_names ); i++ )
-		if( strcmp( magic_names[i], buf ) == 0 ) 
+	for( index = 0; index < IM_NUMBER( magic_names ); index++ )
+		if( strcmp( magic_names[index], buf ) == 0 ) 
 			break;
-	if( i == IM_NUMBER( magic_names ) ) {
+	if( index == IM_NUMBER( magic_names ) ) {
 		im_error( "im_ppm2vips", "%s", _( "bad magic number" ) );
 		return( -1 );
 	}
-	*bits = lookup_bits[i];
-	bands = lookup_bands[i];
-	*ascii = lookup_ascii[i];
+	*bits = lookup_bits[index];
+	bands = lookup_bands[index];
+	*ascii = lookup_ascii[index];
+
+	/* Default ... can be changed below for PFM images.
+	 */
+	*msb_first = 0;
 
 	/* Read in size.
 	 */
-	if( (width = read_uint( fp )) < 0 ||
-		(height = read_uint( fp )) < 0 )
+	if( read_int( fp, &width ) ||
+		read_int( fp, &height ) )
 		return( -1 );
 
-	/* Read in max value for >1 bit images.
+	/* Read in max value / scale for >1 bit images.
 	 */
 	if( *bits > 1 ) {
-		if( (max_value = read_uint( fp )) < 0 )
-			return( -1 );
+		if( index == 6 || index == 7 ) {
+			float scale;
 
-		if( max_value > 255 )
-			*bits = 16;
-		if( max_value > 65535 )
-			*bits = 32;
+			if( read_float( fp, &scale ) )
+				return( -1 );
+
+			/* Scale > 0 means big-endian.
+			 */
+			*msb_first = scale > 0;
+			im_meta_set_double( out, "pfm-scale", fabs( scale ) );
+		}
+		else {
+			int max_value;
+
+			if( read_int( fp, &max_value ) )
+				return( -1 );
+
+			if( max_value > 255 )
+				*bits = 16;
+			if( max_value > 65535 )
+				*bits = 32;
+		}
 	}
 
 	/* For binary images, there is always exactly 1 more whitespace
@@ -210,11 +229,14 @@ read_header( FILE *fp, IMAGE *out, int *bits, int *ascii )
 		break;
 
 	case 32:
-		fmt = IM_BANDFMT_UINT;
+		if( index == 6 || index == 7 )
+			fmt = IM_BANDFMT_FLOAT;
+		else
+			fmt = IM_BANDFMT_UINT;
 		break;
 
 	default:
-		assert( 0 );
+		g_assert( 0 );
 	}
 
 	if( bands == 1 ) {
@@ -244,7 +266,7 @@ read_header( FILE *fp, IMAGE *out, int *bits, int *ascii )
 /* Read a ppm/pgm file using mmap().
  */
 static int
-read_mmap( FILE *fp, const char *filename, IMAGE *out )
+read_mmap( FILE *fp, const char *filename, int msb_first, IMAGE *out )
 {
 	const int header_offset = ftell( fp );
 	IMAGE *t[2];
@@ -255,7 +277,7 @@ read_mmap( FILE *fp, const char *filename, IMAGE *out )
 			IM_IMAGE_SIZEOF_PEL( out ), header_offset ) ||
 		im_copy_morph( t[0], t[1],
 			out->Bands, out->BandFmt, out->Coding ) ||
-		im_copy_native( t[1], out, TRUE ) ) 
+		im_copy_native( t[1], out, msb_first ) ) 
 		return( -1 );
 
 	return( 0 );
@@ -277,7 +299,7 @@ read_ascii( FILE *fp, IMAGE *out )
 		for( x = 0; x < out->Xsize * out->Bands; x++ ) {
 			int val;
 
-			if( (val = read_uint( fp )) < 0 )
+			if( read_int( fp, &val ) )
 				return( -1 );
 			
 			switch( out->BandFmt ) {
@@ -295,7 +317,7 @@ read_ascii( FILE *fp, IMAGE *out )
 				break;
 
 			default:
-				assert( 0 );
+				g_assert( 0 );
 			}
 		}
 
@@ -322,7 +344,7 @@ read_1bit_ascii( FILE *fp, IMAGE *out )
 		for( x = 0; x < out->Xsize * out->Bands; x++ ) {
 			int val;
 
-			if( (val = read_uint( fp )) < 0 )
+			if( read_int( fp, &val ) )
 				return( -1 );
 
 			if( val == 1 )
@@ -372,14 +394,15 @@ parse_ppm( FILE *fp, const char *filename, IMAGE *out )
 {
 	int bits;
 	int ascii;
+	int msb_first;
 
-	if( read_header( fp, out, &bits, &ascii ) )
+	if( read_header( fp, out, &bits, &ascii, &msb_first ) )
 		return( -1 );
 
 	/* What sort of read are we doing?
 	 */
 	if( !ascii && bits >= 8 )
-		return( read_mmap( fp, filename, out ) );
+		return( read_mmap( fp, filename, msb_first, out ) );
 	else if( !ascii && bits == 1 )
 		return( read_1bit_binary( fp, out ) );
 	else if( ascii && bits == 1 )
@@ -394,10 +417,11 @@ ppm2vips_header( const char *filename, IMAGE *out )
         FILE *fp;
 	int bits;
 	int ascii;
+	int msb_first;
 
 	if( !(fp = im__file_open_read( filename, NULL )) ) 
                 return( -1 );
-	if( read_header( fp, out, &bits, &ascii ) ) {
+	if( read_header( fp, out, &bits, &ascii, &msb_first ) ) {
 		fclose( fp );
 		return( -1 );
 	}
@@ -416,6 +440,7 @@ isppmmmap( const char *filename )
         FILE *fp;
 	int bits;
 	int ascii;
+	int msb_first;
 
 	if( !(fp = im__file_open_read( filename, NULL )) ) 
                 return( -1 );
@@ -424,7 +449,7 @@ isppmmmap( const char *filename )
 		fclose( fp );
 		return( 0 );
 	}
-	if( read_header( fp, im, &bits, &ascii ) ) {
+	if( read_header( fp, im, &bits, &ascii, &msb_first ) ) {
 		im_close( im );
 		fclose( fp );
 		return( 0 );
@@ -440,12 +465,14 @@ isppmmmap( const char *filename )
  * @filename: file to load
  * @out: image to write to
  *
- * Read a PPM/PBM/PGM file into a VIPS image. 
+ * Read a PPM/PBM/PGM/PFM file into a VIPS image. 
  * It can read 1, 8, 16 and 32 bit images, colour or monochrome,
  * stored in binary or in ASCII. One bit images become 8 bit VIPS images, 
  * with 0 and 255 for 0 and 1.
  *
- * See also: #VipsFormat, im_vips2ppm().
+ * PFM images have the scale factor attached as "pfm-scale".
+ *
+ * See also: #VipsFormat, im_vips2ppm(), im_meta_get_double()
  *
  * Returns: 0 on success, -1 on error.
  */
@@ -491,7 +518,7 @@ ppm_flags( const char *filename )
 	return( flags );
 }
 
-static const char *ppm_suffs[] = { ".ppm", ".pgm", ".pbm", NULL };
+static const char *ppm_suffs[] = { ".ppm", ".pgm", ".pbm", ".pfm", NULL };
 
 /* ppm format adds no new members.
  */
@@ -505,7 +532,7 @@ vips_format_ppm_class_init( VipsFormatPpmClass *class )
 	VipsFormatClass *format_class = (VipsFormatClass *) class;
 
 	object_class->nickname = "ppm";
-	object_class->description = _( "PPM/PBM/PNM" );
+	object_class->description = _( "PPM/PBM/PNM/PFM" );
 
 	format_class->is_a = isppm;
 	format_class->header = ppm2vips_header;
diff --git a/libvips/format/im_vips2jpeg.c b/libvips/format/im_vips2jpeg.c
index 5236ba58..9c8f58b7 100644
--- a/libvips/format/im_vips2jpeg.c
+++ b/libvips/format/im_vips2jpeg.c
@@ -219,6 +219,15 @@ write_destroy( Write *write )
 	im_free( write );
 }
 
+#define UC IM_BANDFMT_UCHAR
+
+/* Type promotion for save ... just always go to uchar.
+ */
+static int bandfmt_jpeg[10] = {
+/* UC  C   US  S   UI  I   F   X   D   DX */
+   UC, UC, UC, UC, UC, UC, UC, UC, UC, UC
+};
+
 static Write *
 write_new( IMAGE *in )
 {
@@ -228,13 +237,13 @@ write_new( IMAGE *in )
 		return( NULL );
 	memset( write, 0, sizeof( Write ) );
 
-	if( !(write->in = im__convert_saveable( in, IM__RGB_CMYK, FALSE )) ) {
+	if( !(write->in = im__convert_saveable( in, 
+		IM__RGB_CMYK, bandfmt_jpeg )) ) {
 		im_error( "im_vips2jpeg", 
 			"%s", _( "unable to convert to saveable format" ) );
 		write_destroy( write );
 		return( NULL );
-	}
-
+	} 
 	write->row_pointer = NULL;
         write->cinfo.err = jpeg_std_error( &write->eman.pub );
 	write->eman.pub.error_exit = new_error_exit;
diff --git a/libvips/format/im_vips2png.c b/libvips/format/im_vips2png.c
index 8e0b2fc8..7fb83431 100644
--- a/libvips/format/im_vips2png.c
+++ b/libvips/format/im_vips2png.c
@@ -117,6 +117,16 @@ write_destroy( Write *write )
 	im_free( write );
 }
 
+#define UC IM_BANDFMT_UCHAR
+#define US IM_BANDFMT_USHORT
+
+/* Type promotion for save ... uchar or ushort.
+ */
+static int bandfmt_png[10] = {
+/* UC  C   US  S   UI  I   F   X   D   DX */
+   US, UC, US, US, US, US, UC, UC, UC, UC
+};
+
 static Write *
 write_new( IMAGE *in )
 {
@@ -126,7 +136,7 @@ write_new( IMAGE *in )
 		return( NULL );
 	memset( write, 0, sizeof( Write ) );
 
-	if( !(write->in = im__convert_saveable( in, IM__RGBA, TRUE )) ) {
+	if( !(write->in = im__convert_saveable( in, IM__RGBA, bandfmt_png )) ) {
 		im_error( "im_vips2png", 
 			"%s", _( "unable to convert to saveable format" ) );
 		write_destroy( write );
diff --git a/libvips/format/im_vips2ppm.c b/libvips/format/im_vips2ppm.c
index 3436eb30..f869ab62 100644
--- a/libvips/format/im_vips2ppm.c
+++ b/libvips/format/im_vips2ppm.c
@@ -9,6 +9,8 @@
  * 4/2/10
  * 	- gtkdoc
  * 	- cleanups
+ * 1/5/10
+ * 	- add PFM (portable float map) support
  */
 
 /*
@@ -44,7 +46,6 @@
 
 #include <ctype.h>
 #include <stdio.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
@@ -100,14 +101,10 @@ static int
 write_ppm_line_ascii( IMAGE *in, FILE *fp, PEL *p )
 {
 	const int sk = IM_IMAGE_SIZEOF_PEL( in );
-	const int nb = IM_MIN( 3, in->Bands );
 	int x, k;
 
-	/* If IM_CODING_LABQ, write 3 bands.
-	 */
-
 	for( x = 0; x < in->Xsize; x++ ) {
-		for( k = 0; k < nb; k++ ) {
+		for( k = 0; k < in->Bands; k++ ) {
 			switch( in->BandFmt ) {
 			case IM_BANDFMT_UCHAR:
 				fprintf( fp, "%d ", p[k] );
@@ -122,7 +119,7 @@ write_ppm_line_ascii( IMAGE *in, FILE *fp, PEL *p )
 				break;
 
 			default:
-				assert( 0 );
+				g_assert( 0 );
 			}
 		}
 
@@ -143,18 +140,10 @@ write_ppm_line_ascii( IMAGE *in, FILE *fp, PEL *p )
 static int
 write_ppm_line_binary( IMAGE *in, FILE *fp, PEL *p )
 {
-	const int sk = IM_IMAGE_SIZEOF_PEL( in );
-	const int nb = IM_MIN( 3, in->Bands );
-	int x;
-
-	for( x = 0; x < in->Xsize; x++ ) {
-		if( !fwrite( p, 1, nb, fp ) ) {
-			im_error( "im_vips2ppm", 
-				"%s", _( "write error ... disc full?" ) );
-			return( -1 );
-		}
-
-		p += sk;
+	if( !fwrite( p, IM_IMAGE_SIZEOF_LINE( in ), 1, fp ) ) {
+		im_error( "im_vips2ppm", 
+			"%s", _( "write error ... disc full?" ) );
+		return( -1 );
 	}
 
 	return( 0 );
@@ -181,28 +170,14 @@ write_ppm( Write *write, int ascii )
 {
 	IMAGE *in = write->in;
 
-	int max_value;
 	char *magic;
 	time_t timebuf;
 
-	switch( in->BandFmt ) {
-	case IM_BANDFMT_UCHAR:
-		max_value = UCHAR_MAX;
-		break;
-
-	case IM_BANDFMT_USHORT:
-		max_value = USHRT_MAX;
-		break;
-
-	case IM_BANDFMT_UINT:
-		max_value = UINT_MAX;
-		break;
-
-	default:
-		assert( 0 );
-	}
-
-	if( in->Bands == 1 && ascii )
+	if( in->BandFmt == IM_BANDFMT_FLOAT && in->Bands == 3 ) 
+		magic = "PF";
+	else if( in->BandFmt == IM_BANDFMT_FLOAT && in->Bands == 1 ) 
+		magic = "Pf";
+	else if( in->Bands == 1 && ascii )
 		magic = "P2";
 	else if( in->Bands == 1 && !ascii )
 		magic = "P5";
@@ -211,13 +186,41 @@ write_ppm( Write *write, int ascii )
 	else if( in->Bands == 3 && !ascii )
 		magic = "P6";
 	else
-		assert( 0 );
+		g_assert( 0 );
 
 	fprintf( write->fp, "%s\n", magic );
 	time( &timebuf );
 	fprintf( write->fp, "#im_vips2ppm - %s\n", ctime( &timebuf ) );
 	fprintf( write->fp, "%d %d\n", in->Xsize, in->Ysize );
-	fprintf( write->fp, "%d\n", max_value );
+
+	switch( in->BandFmt ) {
+	case IM_BANDFMT_UCHAR:
+		fprintf( write->fp, "%d\n", UCHAR_MAX );
+		break;
+
+	case IM_BANDFMT_USHORT:
+		fprintf( write->fp, "%d\n", USHRT_MAX );
+		break;
+
+	case IM_BANDFMT_UINT:
+		fprintf( write->fp, "%d\n", UINT_MAX );
+		break;
+
+	case IM_BANDFMT_FLOAT:
+{
+		double scale;
+
+		if( im_meta_get_double( in, "pfm-scale", &scale ) )
+			scale = 1;
+		if( !im_amiMSBfirst() )
+			scale *= -1;
+		fprintf( write->fp, "%g\n", scale );
+}
+		break;
+
+	default:
+		g_assert( 0 );
+	}
 
 	write->fn = ascii ? write_ppm_line_ascii : write_ppm_line_binary;
 
@@ -233,9 +236,12 @@ write_ppm( Write *write, int ascii )
  * @filename: file to write to 
  *
  * Write a VIPS image to a file as PPM. It can write 8, 16 or
- * 32 bit unsigned integer images, colour or monochrome, stored as binary or 
- * ASCII. 
- * Images of more than 8 bits can only be stored in ASCII.
+ * 32 bit unsigned integer images, float images, colour or monochrome, 
+ * stored as binary or ASCII. 
+ * Integer images of more than 8 bits can only be stored in ASCII.
+ *
+ * When writing float (PFM) images the scale factor is set from the 
+ * "pfm-scale" metadata.
  *
  * The storage format is indicated by a filename extension, for example:
  *
@@ -245,7 +251,7 @@ write_ppm( Write *write, int ascii )
  *
  * will write to "fred.ppm" in ascii format. The default is binary.
  *
- * See also: #VipsFormat, im_ppm2vips().
+ * See also: #VipsFormat, im_ppm2vips(), im_meta_set_double().
  *
  * Returns: 0 on success, -1 on error.
  */
@@ -277,17 +283,22 @@ im_vips2ppm( IMAGE *in, const char *filename )
 		}
 	}
 
-	if( im_bits_of_fmt( in->BandFmt ) > 8 && !ascii ) {
-		im_error( "im_vips2ppm", 
-			"%s", _( "can't write binary >8 bit images" ) );
-		return( -1 );
-	}
-	if( im_check_uint( "im_vips2ppm", in ) || 
+	if( im_check_uintorf( "im_vips2ppm", in ) || 
 		im_check_bands_1or3( "im_vips2ppm", in ) || 
 		im_check_uncoded( "im_vips2ppm", in ) || 
 		im_pincheck( in ) )
 		return( -1 );
 
+	/* We can only write >8 bit binary images in float.
+	 */
+	if( im_bits_of_fmt( in->BandFmt ) > 8 && 
+		!ascii && 
+		in->BandFmt != IM_BANDFMT_FLOAT ) {
+		im_error( "im_vips2ppm", 
+			"%s", _( "binary >8 bit images must be float" ) );
+		return( -1 );
+	}
+
 	if( !(write = write_new( in, name )) )
 		return( -1 );
 
diff --git a/libvips/format/im_vips2tiff.c b/libvips/format/im_vips2tiff.c
index 0464f7ff..bb8f695f 100644
--- a/libvips/format/im_vips2tiff.c
+++ b/libvips/format/im_vips2tiff.c
@@ -1690,12 +1690,9 @@ im_vips2tiff( IMAGE *in, const char *filename )
 
 	/* Check input image.
 	 */
-	if( im_pincheck( in ) )
+	if( im_pincheck( in ) ||
+		im_check_coding_known( "im_vips2tiff", in ) )
 		return( -1 );
-	if( in->Coding != IM_CODING_LABQ && in->Coding != IM_CODING_NONE ) {
-		im_error( "im_vips2tiff", "%s", _( "unknown coding type" ) );
-		return( -1 );
-	}
 	if( in->BandFmt != IM_BANDFMT_UCHAR && 
 		!(in->BandFmt == IM_BANDFMT_SHORT && 
 			in->Type == IM_TYPE_LABS) &&
diff --git a/libvips/include/vips/check.h b/libvips/include/vips/check.h
index f57130bd..000ba2bc 100644
--- a/libvips/include/vips/check.h
+++ b/libvips/include/vips/check.h
@@ -57,6 +57,7 @@ int im_check_bands_same( const char *domain, IMAGE *im1, IMAGE *im2 );
 int im_check_bandno( const char *domain, IMAGE *im, int bandno );
 int im_check_int( const char *domain, IMAGE *im );
 int im_check_uint( const char *domain, IMAGE *im );
+int im_check_uintorf( const char *domain, IMAGE *im );
 int im_check_noncomplex( const char *domain, IMAGE *im );
 int im_check_complex( const char *domain, IMAGE *im );
 int im_check_format( const char *domain, IMAGE *im, VipsBandFmt fmt );
diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index 345579c1..8278eef0 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -126,13 +126,14 @@ extern int im__read_test;
 extern GMutex *im__global_lock;
 
 typedef enum {
-	IM__RGB,	/* 1 or 3 bands (like PPM) */
-	IM__RGBA,	/* 1, 2, 3 or 4 bands (like PNG) */
-	IM__RGB_CMYK	/* 1, 3 or 4 bands (like JPEG) */
+	IM__RGB,	/* 1 or 3 bands (eg. PPM) */
+	IM__RGBA,	/* 1, 2, 3 or 4 bands (eg. PNG) */
+	IM__RGB_CMYK,	/* 1, 3 or 4 bands (eg. JPEG) */
+	IM__ANY		/* any number of bands (eg. TIFF) */
 } im__saveable_t;
 
 IMAGE *im__convert_saveable( IMAGE *in, 
-	im__saveable_t saveable, gboolean sixteen );
+	im__saveable_t saveable, int format_table[10] );
 
 void im__link_break_all( IMAGE *im );
 void *im__link_map( IMAGE *im, VSListMap2Fn fn, void *a, void *b );
diff --git a/libvips/iofuncs/check.c b/libvips/iofuncs/check.c
index 38712351..87df0d9b 100644
--- a/libvips/iofuncs/check.c
+++ b/libvips/iofuncs/check.c
@@ -947,6 +947,33 @@ im_check_u8or16orf( const char *domain, IMAGE *im )
 	return( 0 );
 }
 
+/**
+ * im_check_uintorf:
+ * @domain: the originating domain for the error message
+ * @im: image to check
+ *
+ * Check that the image is unsigned int or float.
+ * Otherwise set an error message and return non-zero.
+ *
+ * See also: im_error().
+ *
+ * Returns: 0 if OK, -1 otherwise.
+ */
+int
+im_check_uintorf( const char *domain, IMAGE *im )
+{
+	if( im->BandFmt != IM_BANDFMT_UCHAR &&
+		im->BandFmt != IM_BANDFMT_USHORT &&
+		im->BandFmt != IM_BANDFMT_UINT &&
+		im->BandFmt != IM_BANDFMT_FLOAT ) {
+		im_error( domain, "%s", 
+			_( "image must be unsigned int or float" ) );
+		return( -1 );
+	}
+
+	return( 0 );
+}
+
 /**
  * im_check_size_same:
  * @domain: the originating domain for the error message