diff --git a/sys/man/1/jpg b/sys/man/1/jpg
index 9ec0153fc..e242fa6e8 100644
--- a/sys/man/1/jpg
+++ b/sys/man/1/jpg
@@ -1,6 +1,6 @@
 .TH JPG 1
 .SH NAME
-jpg, gif, png, ppm, bmp, v210, yuv, ico, tga, tojpg, togeordi, togif, toppm, topng, toico \- view and convert pictures
+jpg, gif, png, tif, ppm, bmp, v210, yuv, ico, tga, tojpg, togeordi, togif, toppm, topng, toico \- view and convert pictures
 .SH SYNOPSIS
 .B jpg
 [
@@ -23,6 +23,13 @@ jpg, gif, png, ppm, bmp, v210, yuv, ico, tga, tojpg, togeordi, togif, toppm, top
 .I file ...
 ]
 .br
+.B tif
+[
+.B -39cdektv
+] [
+.I file ...
+]
+.br
 .B ppm
 [
 .B -39cdektv
@@ -137,6 +144,7 @@ These programs read, display, and write image files in public formats.
 .IR Jpg ,
 .IR gif ,
 .IR png ,
+.IR tif ,
 .IR ppm ,
 .IR bmp ,
 .IR tga ,
@@ -156,8 +164,14 @@ read Plan 9 images files, convert them to JPEG, GIF, PPM, or PNG, and write them
 The default behavior of
 .IR jpg ,
 .IR gif ,
+.IR png ,
+.IR tif ,
+.IR ppm ,
+.IR bmp ,
+.IR tga ,
+.IR v210 ,
 and
-.IR ppm
+.IR yuv
 is to display the
 .IR file ,
 or standard input if no file is named.
@@ -227,11 +241,12 @@ The input is a motion JPEG file, with multiple images representing frames of the
 .PP
 The
 .IR tojpg ,
-.IR togif
-and
+.IR togif ,
 .IR toppm
-programs go the other way: they convert from Plan 9 images to JPEG, GIF and PPM,
-and have no display capability.
+and
+.IR topng
+programs go the other way: they convert from Plan 9 images to JPEG, GIF,
+PPM and PNG and have no display capability.
 They all accept an option
 .B -c
 to set the comment field of the resulting file.
@@ -323,6 +338,8 @@ space in the image.  The icon file is written to standard output.
 .br
 .B http://www.w3.org/TR/2003/REC-PNG-20031110
 .br
+.B http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
+.br
 .B http://netpbm.sourceforge.net/doc/ppm.html
 .br
 .B http://en.wikipedia.org/wiki/Windows_bitmap
diff --git a/sys/src/cmd/jpg/imagefile.h b/sys/src/cmd/jpg/imagefile.h
index bab62e84e..04600e364 100644
--- a/sys/src/cmd/jpg/imagefile.h
+++ b/sys/src/cmd/jpg/imagefile.h
@@ -50,9 +50,11 @@ typedef struct ImageInfo {
 
 
 Rawimage**	readjpg(int, int);
-Rawimage**	Breadjpg(Biobuf *b, int);
+Rawimage**	Breadjpg(Biobuf*, int);
 Rawimage**	readpng(int, int);
-Rawimage**	Breadpng(Biobuf *b, int);
+Rawimage**	Breadpng(Biobuf*, int);
+Rawimage**	readtif(int);
+Rawimage**	Breadtif(Biobuf*);
 Rawimage**	readgif(int, int);
 Rawimage**	readpixmap(int, int);
 Rawimage*	torgbv(Rawimage*, int);
diff --git a/sys/src/cmd/jpg/mkfile b/sys/src/cmd/jpg/mkfile
index 3671856e9..0455f2cc9 100644
--- a/sys/src/cmd/jpg/mkfile
+++ b/sys/src/cmd/jpg/mkfile
@@ -9,6 +9,7 @@ TARG=\
 	toppm\
 	png\
 	topng\
+	tif\
 	yuv\
 	ico\
 	toico\
@@ -55,6 +56,7 @@ $O.ppm:		$IMFILES readppm.$O ppm.$O
 $O.toppm:	writeppm.$O multichan.$O toppm.$O
 $O.png:		$IMFILES readpng.$O png.$O
 $O.topng:	writepng.$O topng.$O
+$O.tif:		$IMFILES readtif.$O tif.$O
 $O.yuv:		$IMFILES readyuv.$O yuv.$O
 $O.bmp:		$IMFILES readbmp.$O bmp.$O
 $O.v210:	$IMFILES readv210.$O v210.$O
diff --git a/sys/src/cmd/jpg/readtif.c b/sys/src/cmd/jpg/readtif.c
new file mode 100644
index 000000000..75c80f27f
--- /dev/null
+++ b/sys/src/cmd/jpg/readtif.c
@@ -0,0 +1,1787 @@
+/*
+* code/documentation:
+* http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf
+* http://paulbourke.net/dataformats/tiff/
+* http://www.fileformat.info/format/tiff/egff.htm
+* http://www.fileformat.info/mirror/egff/ch09_05.htm
+* http://www.itu.int/rec/T-REC-T.4-199904-S/en
+* http://www.itu.int/rec/T-REC-T.6-198811-I/en
+*
+* fax codes and lzw:
+* http://www.remotesensing.org/libtiff/
+*/
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <draw.h>
+#include "imagefile.h"
+
+enum {
+	II = 0x4949, /* little-endian */
+	MM = 0x4d4d, /* big-endian */
+	TIF = 0x002a /* tiff magic number */
+};
+
+enum {
+	Byte = 1,
+	Short = 3,
+	Long = 4
+};
+
+enum {
+	Width = 0x0100,
+	Length = 0x0101,
+	Bits = 0x0102,
+
+	Compression = 0x0103,
+	Nocomp = 0x0001,
+	Huffman = 0x0002,
+	T4enc = 0x0003,
+	T6enc = 0x0004,
+	Lzwenc = 0x0005,
+	Packbits = 0x8005,
+
+	Photometric = 0x0106,
+	Whitezero = 0x0000,
+	Blackzero = 0x0001,
+	Rgb = 0x0002,
+	Palette = 0x0003,
+
+	Fill = 0x010a,
+	Strips = 0x0111,
+	Orientation = 0x0112,
+	Samples = 0x0115,
+	Rows = 0x0116,
+	Counts = 0x0117,
+	Planar = 0x011c,
+	T4opts = 0x0124,
+	T6opts = 0x0125,
+	Predictor = 0x13d,
+	Color = 0x0140
+};
+
+enum {
+	Nfaxcodes = 10,
+	Nfaxtab = 105
+};
+
+enum {
+	Clrcode = 256,
+	Eoicode = 257,
+	Tabsz = 1<<12
+};
+
+typedef struct Tab Tab;
+typedef struct Fax Fax;
+typedef struct Code Code;
+typedef struct Lzw Lzw;
+typedef struct Fld Fld;
+typedef struct Tif Tif;
+
+struct Tab {
+	int len;
+	int code;
+	int run; /* run length */
+};
+
+struct Fax {
+	ulong n;
+	int m;
+	int st; /* state */
+	Tab *tab[2];
+	int ntab; /* position in tab */
+	Tab *eol;
+	int (*getbit)(Fax *);
+	int *l1;
+	int *l2;
+	ulong nl;
+	uchar *data;
+	ulong next; /* next strip offset in data */
+};
+
+struct Code {
+	uchar val;
+	Code *next;
+};
+
+struct Lzw {
+	Code tab[Tabsz];
+	int ntab;
+	int len; /* code length */
+	ulong n;
+	int m;
+	uchar *data;
+	ulong next; /* next strip offset in data */
+	/* remaining allocated codes */
+	Code *first;
+	Code *last;
+};
+
+struct Fld {
+	uint tag;
+	uint typ;
+	ulong cnt;
+	ulong off; /* value offset */
+	ulong *val;
+	ulong nval;
+};
+
+struct Tif {
+	Biobuf *fd;
+	uint end; /* endianness */
+	uchar tmp[4];
+	uchar *buf;
+	ulong nbuf;
+	int eof; /* reached end of image */
+	ulong n; /* offset in buf array */
+	ulong off;
+	uint nfld;
+	Fld *fld;
+	ulong (*byte2)(uchar *);
+	ulong (*byte4)(uchar *);
+
+	/* field data */
+	ulong dx;
+	ulong dy;
+	ulong depth;
+	ulong comp;
+	uchar *(*uncompress)(Tif *);
+	ulong orientation;
+	ulong photo;
+	int (*decode)(Tif *, Rawimage *, uchar *);
+	ulong fill;
+	ulong *strips;
+	ulong nstrips;
+	ulong samples;
+	ulong rows;
+	ulong *counts;
+	ulong ncounts;
+	ulong planar;
+	ulong *color; /* color map */
+	ulong ncolor;
+	ulong t4;
+	ulong t6;
+	ulong predictor;
+
+	/* image data */
+	uchar *data;
+	ulong ndata;
+};
+
+/*
+* imported from libdraw/arith.c to permit
+* extern log2 function
+*/
+static int log2[] = {
+	-1, 0, 1, -1, 2, -1, -1, -1, 3,
+	-1, -1, -1, -1, -1, -1, -1, 4,
+	-1, -1, -1, -1, -1, -1, -1, 4 /* BUG */,
+	-1, -1, -1, -1, -1, -1, -1, 5
+};
+
+static Tab faxwhite[Nfaxtab] = {
+	{4, 0x7, 2}, /* 0111 */
+	{4, 0x8, 3}, /* 1000 */
+	{4, 0xb, 4}, /* 1011 */
+	{4, 0xc, 5}, /* 1100 */
+	{4, 0xe, 6}, /* 1110 */
+	{4, 0xf, 7}, /* 1111 */
+	{5, 0x12, 128}, /* 1001 0 */
+	{5, 0x13, 8}, /* 1001 1 */
+	{5, 0x14, 9}, /* 1010 0 */
+	{5, 0x1b, 64}, /* 1101 1 */
+	{5, 0x7, 10}, /* 0011 1 */
+	{5, 0x8, 11}, /* 0100 0 */
+	{6, 0x17, 192}, /* 0101 11 */
+	{6, 0x18, 1664}, /* 0110 00 */
+	{6, 0x2a, 16}, /* 1010 10 */
+	{6, 0x2b, 17}, /* 1010 11 */
+	{6, 0x3, 13}, /* 0000 11 */
+	{6, 0x34, 14}, /* 1101 00 */
+	{6, 0x35, 15}, /* 1101 01 */
+	{6, 0x7, 1}, /* 0001 11 */
+	{6, 0x8, 12}, /* 0010 00 */
+	{7, 0x13, 26}, /* 0010 011 */
+	{7, 0x17, 21}, /* 0010 111 */
+	{7, 0x18, 28}, /* 0011 000 */
+	{7, 0x24, 27}, /* 0100 100 */
+	{7, 0x27, 18}, /* 0100 111 */
+	{7, 0x28, 24}, /* 0101 000 */
+	{7, 0x2b, 25}, /* 0101 011 */
+	{7, 0x3, 22}, /* 0000 011 */
+	{7, 0x37, 256}, /* 0110 111 */
+	{7, 0x4, 23}, /* 0000 100 */
+	{7, 0x8, 20}, /* 0001 000 */
+	{7, 0xc, 19}, /* 0001 100 */
+	{8, 0x12, 33}, /* 0001 0010 */
+	{8, 0x13, 34}, /* 0001 0011 */
+	{8, 0x14, 35}, /* 0001 0100 */
+	{8, 0x15, 36}, /* 0001 0101 */
+	{8, 0x16, 37}, /* 0001 0110 */
+	{8, 0x17, 38}, /* 0001 0111 */
+	{8, 0x1a, 31}, /* 0001 1010 */
+	{8, 0x1b, 32}, /* 0001 1011 */
+	{8, 0x2, 29}, /* 0000 0010 */
+	{8, 0x24, 53}, /* 0010 0100 */
+	{8, 0x25, 54}, /* 0010 0101 */
+	{8, 0x28, 39}, /* 0010 1000 */
+	{8, 0x29, 40}, /* 0010 1001 */
+	{8, 0x2a, 41}, /* 0010 1010 */
+	{8, 0x2b, 42}, /* 0010 1011 */
+	{8, 0x2c, 43}, /* 0010 1100 */
+	{8, 0x2d, 44}, /* 0010 1101 */
+	{8, 0x3, 30}, /* 0000 0011 */
+	{8, 0x32, 61}, /* 0011 0010 */
+	{8, 0x33, 62}, /* 0011 0011 */
+	{8, 0x34, 63}, /* 0011 0100 */
+	{8, 0x35, 0}, /* 0011 0101 */
+	{8, 0x36, 320}, /* 0011 0110 */
+	{8, 0x37, 384}, /* 0011 0111 */
+	{8, 0x4, 45}, /* 0000 0100 */
+	{8, 0x4a, 59}, /* 0100 1010 */
+	{8, 0x4b, 60}, /* 0100 1011 */
+	{8, 0x5, 46}, /* 0000 0101 */
+	{8, 0x52, 49}, /* 0101 0010 */
+	{8, 0x53, 50}, /* 0101 0011 */
+	{8, 0x54, 51}, /* 0101 0100 */
+	{8, 0x55, 52}, /* 0101 0101 */
+	{8, 0x58, 55}, /* 0101 1000 */
+	{8, 0x59, 56}, /* 0101 1001 */
+	{8, 0x5a, 57}, /* 0101 1010 */
+	{8, 0x5b, 58}, /* 0101 1011 */
+	{8, 0x64, 448}, /* 0110 0100 */
+	{8, 0x65, 512}, /* 0110 0101 */
+	{8, 0x67, 640}, /* 0110 0111 */
+	{8, 0x68, 576}, /* 0110 1000 */
+	{8, 0xa, 47}, /* 0000 1010 */
+	{8, 0xb, 48}, /* 0000 1011 */
+	{9, 0x98, 1472}, /* 0100 1100 0 */
+	{9, 0x99, 1536}, /* 0100 1100 1 */
+	{9, 0x9a, 1600}, /* 0100 1101 0 */
+	{9, 0x9b, 1728}, /* 0100 1101 1 */
+	{9, 0xcc, 704}, /* 0110 0110 0 */
+	{9, 0xcd, 768}, /* 0110 0110 1 */
+	{9, 0xd2, 832}, /* 0110 1001 0 */
+	{9, 0xd3, 896}, /* 0110 1001 1 */
+	{9, 0xd4, 960}, /* 0110 1010 0 */
+	{9, 0xd5, 1024}, /* 0110 1010 1 */
+	{9, 0xd6, 1088}, /* 0110 1011 0 */
+	{9, 0xd7, 1152}, /* 0110 1011 1 */
+	{9, 0xd8, 1216}, /* 0110 1100 0 */
+	{9, 0xd9, 1280}, /* 0110 1100 1 */
+	{9, 0xda, 1344}, /* 0110 1101 0 */
+	{9, 0xdb, 1408}, /* 0110 1101 1 */
+	{11, 0x8, 1792}, /* 0000 0001 000 */
+	{11, 0xc, 1856}, /* 0000 0001 100 */
+	{11, 0xd, 1920}, /* 0000 0001 101 */
+	{12, 0x1, -1}, /* 0000 0000 0001 */
+	{12, 0x12, 1984}, /* 0000 0001 0010 */
+	{12, 0x13, 2048}, /* 0000 0001 0011 */
+	{12, 0x14, 2112}, /* 0000 0001 0100 */
+	{12, 0x15, 2176}, /* 0000 0001 0101 */
+	{12, 0x16, 2240}, /* 0000 0001 0110 */
+	{12, 0x17, 2304}, /* 0000 0001 0111 */
+	{12, 0x1c, 2368}, /* 0000 0001 1100 */
+	{12, 0x1d, 2432}, /* 0000 0001 1101 */
+	{12, 0x1e, 2496}, /* 0000 0001 1110 */
+	{12, 0x1f, 2560} /* 0000 0001 1111 */
+};
+
+static Tab faxblack[Nfaxtab] = {
+	{2, 0x2, 3}, /* 10 */
+	{2, 0x3, 2}, /* 11 */
+	{3, 0x2, 1}, /* 010 */
+	{3, 0x3, 4}, /* 011 */
+	{4, 0x2, 6}, /* 0010 */
+	{4, 0x3, 5}, /* 0011 */
+	{5, 0x3, 7}, /* 0001 1 */
+	{6, 0x4, 9}, /* 0001 00 */
+	{6, 0x5, 8}, /* 0001 01 */
+	{7, 0x4, 10}, /* 0000 100 */
+	{7, 0x5, 11}, /* 0000 101 */
+	{7, 0x7, 12}, /* 0000 111 */
+	{8, 0x4, 13}, /* 0000 0100 */
+	{8, 0x7, 14}, /* 0000 0111 */
+	{9, 0x18, 15}, /* 0000 1100 0 */
+	{10, 0x17, 16}, /* 0000 0101 11 */
+	{10, 0x18, 17}, /* 0000 0110 00 */
+	{10, 0x37, 0}, /* 0000 1101 11 */
+	{10, 0x8, 18}, /* 0000 0010 00 */
+	{10, 0xf, 64}, /* 0000 0011 11 */
+	{11, 0x17, 24}, /* 0000 0010 111 */
+	{11, 0x18, 25}, /* 0000 0011 000 */
+	{11, 0x28, 23}, /* 0000 0101 000 */
+	{11, 0x37, 22}, /* 0000 0110 111 */
+	{11, 0x67, 19}, /* 0000 1100 111 */
+	{11, 0x68, 20}, /* 0000 1101 000 */
+	{11, 0x6c, 21}, /* 0000 1101 100 */
+	{11, 0x8, 1792}, /* 0000 0001 000 */
+	{11, 0xc, 1856}, /* 0000 0001 100 */
+	{11, 0xd, 1920}, /* 0000 0001 101 */
+	{12, 0x1, -1}, /* 0000 0000 0001 */
+	{12, 0x12, 1984}, /* 0000 0001 0010 */
+	{12, 0x13, 2048}, /* 0000 0001 0011 */
+	{12, 0x14, 2112}, /* 0000 0001 0100 */
+	{12, 0x15, 2176}, /* 0000 0001 0101 */
+	{12, 0x16, 2240}, /* 0000 0001 0110 */
+	{12, 0x17, 2304}, /* 0000 0001 0111 */
+	{12, 0x1c, 2368}, /* 0000 0001 1100 */
+	{12, 0x1d, 2432}, /* 0000 0001 1101 */
+	{12, 0x1e, 2496}, /* 0000 0001 1110 */
+	{12, 0x1f, 2560}, /* 0000 0001 1111 */
+	{12, 0x24, 52}, /* 0000 0010 0100 */
+	{12, 0x27, 55}, /* 0000 0010 0111 */
+	{12, 0x28, 56}, /* 0000 0010 1000 */
+	{12, 0x2b, 59}, /* 0000 0010 1011 */
+	{12, 0x2c, 60}, /* 0000 0010 1100 */
+	{12, 0x33, 320}, /* 0000 0011 0011 */
+	{12, 0x34, 384}, /* 0000 0011 0100 */
+	{12, 0x35, 448}, /* 0000 0011 0101 */
+	{12, 0x37, 53}, /* 0000 0011 0111 */
+	{12, 0x38, 54}, /* 0000 0011 1000 */
+	{12, 0x52, 50}, /* 0000 0101 0010 */
+	{12, 0x53, 51}, /* 0000 0101 0011 */
+	{12, 0x54, 44}, /* 0000 0101 0100 */
+	{12, 0x55, 45}, /* 0000 0101 0101 */
+	{12, 0x56, 46}, /* 0000 0101 0110 */
+	{12, 0x57, 47}, /* 0000 0101 0111 */
+	{12, 0x58, 57}, /* 0000 0101 1000 */
+	{12, 0x59, 58}, /* 0000 0101 1001 */
+	{12, 0x5a, 61}, /* 0000 0101 1010 */
+	{12, 0x5b, 256}, /* 0000 0101 1011 */
+	{12, 0x64, 48}, /* 0000 0110 0100 */
+	{12, 0x65, 49}, /* 0000 0110 0101 */
+	{12, 0x66, 62}, /* 0000 0110 0110 */
+	{12, 0x67, 63}, /* 0000 0110 0111 */
+	{12, 0x68, 30}, /* 0000 0110 1000 */
+	{12, 0x69, 31}, /* 0000 0110 1001 */
+	{12, 0x6a, 32}, /* 0000 0110 1010 */
+	{12, 0x6b, 33}, /* 0000 0110 1011 */
+	{12, 0x6c, 40}, /* 0000 0110 1100 */
+	{12, 0x6d, 41}, /* 0000 0110 1101 */
+	{12, 0xc8, 128}, /* 0000 1100 1000 */
+	{12, 0xc9, 192}, /* 0000 1100 1001 */
+	{12, 0xca, 26}, /* 0000 1100 1010 */
+	{12, 0xcb, 27}, /* 0000 1100 1011 */
+	{12, 0xcc, 28}, /* 0000 1100 1100 */
+	{12, 0xcd, 29}, /* 0000 1100 1101 */
+	{12, 0xd2, 34}, /* 0000 1101 0010 */
+	{12, 0xd3, 35}, /* 0000 1101 0011 */
+	{12, 0xd4, 36}, /* 0000 1101 0100 */
+	{12, 0xd5, 37}, /* 0000 1101 0101 */
+	{12, 0xd6, 38}, /* 0000 1101 0110 */
+	{12, 0xd7, 39}, /* 0000 1101 0111 */
+	{12, 0xda, 42}, /* 0000 1101 1010 */
+	{12, 0xdb, 43}, /* 0000 1101 1011 */
+	{13, 0x4a, 640}, /* 0000 0010 0101 0 */
+	{13, 0x4b, 704}, /* 0000 0010 0101 1 */
+	{13, 0x4c, 768}, /* 0000 0010 0110 0 */
+	{13, 0x4d, 832}, /* 0000 0010 0110 1 */
+	{13, 0x52, 1280}, /* 0000 0010 1001 0 */
+	{13, 0x53, 1344}, /* 0000 0010 1001 1 */
+	{13, 0x54, 1408}, /* 0000 0010 1010 0 */
+	{13, 0x55, 1472}, /* 0000 0010 1010 1 */
+	{13, 0x5a, 1536}, /* 0000 0010 1101 0 */
+	{13, 0x5b, 1600}, /* 0000 0010 1101 1 */
+	{13, 0x64, 1664}, /* 0000 0011 0010 0 */
+	{13, 0x65, 1728}, /* 0000 0011 0010 1 */
+	{13, 0x6c, 512}, /* 0000 0011 0110 0 */
+	{13, 0x6d, 576}, /* 0000 0011 0110 1 */
+	{13, 0x72, 896}, /* 0000 0011 1001 0 */
+	{13, 0x73, 960}, /* 0000 0011 1001 1 */
+	{13, 0x74, 1024}, /* 0000 0011 1010 0 */
+	{13, 0x75, 1088}, /* 0000 0011 1010 1 */
+	{13, 0x76, 1152}, /* 0000 0011 1011 0 */
+	{13, 0x77, 1216} /* 0000 0011 1011 1 */
+};
+
+static Tab faxcodes[Nfaxcodes] = {
+	{1, 0x1, 0}, /* 1 */
+	{3, 0x1, 0}, /* 001 */
+	{3, 0x2, 0}, /* 010 */
+	{3, 0x3, 0}, /* 011 */
+	{4, 0x1, 0}, /* 0001 */
+	{6, 0x2, 0}, /* 0000 10 */
+	{6, 0x3, 0}, /* 0000 11 */
+	{7, 0x2, 0}, /* 0000 010 */
+	{7, 0x3, 0}, /* 0000 011 */
+	{12, 0x1, -1} /* 0000 0000 0001 */
+};
+
+static int typesizes[] = {0, 1, 0, 2, 4};
+static int vcodeval[] = {0, 0, 0, 1, 0, 0, 2, 3};
+
+static ulong byte2le(uchar *);
+static ulong byte4le(uchar *);
+static ulong byte2be(uchar *);
+static ulong byte4be(uchar *);
+static void readdata(Tif *, ulong);
+static void readnbytes(Tif *, ulong);
+static ulong readbyte(Tif *);
+static ulong readshort(Tif *);
+static ulong readlong(Tif *);
+static int gototif(Tif *, ulong);
+static int readheader(Tif *);
+static uchar *nocomp(Tif *);
+static int getbit1(Fax *);
+static int getbit2(Fax *);
+static Tab *findtab(Fax *, int, int, Tab *, int);
+static Tab *gettab(Fax *, int);
+static Tab *geteol(Fax *);
+static int faxfill(Fax *, uchar *, ulong, ulong *, ulong *, ulong, int);
+static void fillbits(Fax *);
+static int faxalloclines(Fax *);
+static Tab *getfax1d(Fax *, uchar *, ulong, ulong *, ulong *, ulong);
+static Tab *getfax2d(Fax *, uchar *, ulong, ulong *, ulong *, ulong);
+static int faxstrip(Tif *, Fax *, uchar *, ulong, ulong *);
+static uchar *fax(Tif *);
+static void tabinit(Lzw *);
+static Code *newcode(Lzw *, Code *);
+static void listadd(Lzw *, Code *);
+static Code *tabadd(Lzw *, Code *, Code *);
+static int getcode(Lzw *);
+static int wstr(uchar *, ulong, ulong *, Code *, long *);
+static void predict(Tif *, uchar *);
+static int lzwstrip(Lzw *, uchar *, ulong, ulong *, long);
+static uchar *lzw(Tif *);
+static uchar *packbits(Tif *);
+static int faxdecode(Tif *, Rawimage *, uchar *);
+static int greydecode(Tif *, Rawimage *, uchar *);
+static int rgbdecode(Tif *, Rawimage *, uchar *);
+static int paldecode(Tif *, Rawimage *, uchar *);
+static int parsefield(Tif *, Fld *);
+static int readfield(Tif *, Fld *);
+static int checkfields(Tif *);
+static int readstrips(Tif *);
+static Rawimage *decode(Tif *);
+static void freefields(Tif *);
+static Rawimage *readslave(Tif *);
+
+static ulong
+byte2le(uchar *buf)
+{
+	return (buf[1] << 8) | buf[0];
+}
+
+static ulong
+byte4le(uchar *buf)
+{
+	return (byte2le(buf+2) << 16) | byte2le(buf);
+}
+
+static ulong
+byte2be(uchar *buf)
+{
+	return (buf[0] << 8) | buf[1];
+}
+
+static ulong
+byte4be(uchar *buf)
+{
+	return (byte2be(buf) << 16) | byte2be(buf+2);
+}
+
+static void
+readdata(Tif *t, ulong offset)
+{
+	long n, m;
+	ulong size;
+
+	if(offset < t->nbuf)
+		offset = t->nbuf;
+	m = offset + 4096 - t->nbuf;
+	size = (m + t->nbuf) * sizeof *t->buf;
+	if(t->buf == nil) {
+		if((t->buf = malloc(size)) == nil)
+			sysfatal("malloc: %r");
+	} else {
+		if((t->buf = realloc(t->buf, size)) == nil)
+			sysfatal("realloc: %r");
+	}
+	if((n = Bread(t->fd, t->buf+t->nbuf, m)) < 0)
+		sysfatal("Bread: %r");
+	if(n != m)
+		t->eof = 1;
+	t->nbuf += n;
+}
+
+static void
+readnbytes(Tif *t, ulong n)
+{
+	if(n <= 0 || n > 4)
+		sysfatal("cannot read %lud bytes", n);
+	if(t->n+n > t->nbuf) {
+		if(t->eof)
+			sysfatal("reached end of file");
+		readdata(t, 0);
+	}
+	memmove(t->tmp, t->buf+t->n, n);
+	t->n += n;
+}
+
+static ulong
+readbyte(Tif *t)
+{
+	readnbytes(t, 1);
+	return t->tmp[0];
+}
+
+static ulong
+readshort(Tif *t)
+{
+	readnbytes(t, 2);
+	return (*t->byte2)(t->tmp);
+}
+
+static ulong
+readlong(Tif *t)
+{
+	readnbytes(t, 4);
+	return (*t->byte4)(t->tmp);
+}
+
+static int
+gototif(Tif *t, ulong n)
+{
+	if(n < 8) {
+		werrstr("offset pointing to header");
+		return -1;
+	}
+	if(n > t->nbuf)
+		readdata(t, n);
+	t->n = n;
+	return 0;
+}
+
+static int
+readheader(Tif *t)
+{
+	uint n;
+
+	t->end = readshort(t);
+	switch(t->end) {
+	case II:
+		break;
+	case MM:
+		t->byte2 = byte2be;
+		t->byte4 = byte4be;
+		break;
+	default:
+		werrstr("illegal byte order: %#.4x", t->end);
+		return -1;
+	}
+	if((n = readshort(t)) != TIF) {
+		werrstr("illegal tiff magic: %#.4x", n);
+		return -1;
+	}
+	t->off = readlong(t);
+	return gototif(t, t->off);
+}
+
+static uchar *
+nocomp(Tif *t)
+{
+	return t->data;
+}
+
+static int
+getbit1(Fax *f)
+{
+	int bit;
+
+	if(f->n >= f->next)
+		return -1;
+	bit = (f->data[f->n] >> f->m) & 0x1;
+	f->m--;
+	if(f->m < 0) {
+		f->n++;
+		f->m = 7;
+	}
+	return bit;
+}
+
+static int
+getbit2(Fax *f)
+{
+	int bit;
+
+	if(f->n >= f->next)
+		return -1;
+	bit = (f->data[f->n] >> f->m) & 0x1;
+	f->m++;
+	if(f->m >= 8) {
+		f->n++;
+		f->m = 0;
+	}
+	return bit;
+}
+
+static Tab *
+findtab(Fax *f, int code, int len, Tab *tab, int max)
+{
+	Tab *p;
+
+	while(f->ntab < max) {
+		p = &tab[f->ntab];
+		if(p->len > len)
+			break;
+		if(p->code == code) {
+			f->ntab = 0;
+			return p;
+		}
+		f->ntab++;
+	}
+	return nil;
+}
+
+static Tab *
+gettab(Fax *f, int mode)
+{
+	int i, n, maxlen, bit, code;
+	Tab *p, *tab;
+
+	code = 0;
+	if(mode) {
+		n = Nfaxcodes;
+		tab = faxcodes;
+	} else {
+		n = Nfaxtab;
+		tab = f->tab[f->st];
+	}
+	maxlen = tab[n-1].len;
+	for(i = 1; i <= maxlen; i++) {
+		if((bit = (*f->getbit)(f)) < 0) {
+			f->st = -1;
+			return nil;
+		}
+		code = (code << 1) | bit;
+		if((p = findtab(f, code, i, tab, n)) != nil)
+			return p;
+	}
+	werrstr("code not found");
+	return nil;
+}
+
+static Tab *
+geteol(Fax *f)
+{
+	int i, bit;
+	Tab *p;
+
+	if(f->eol == nil) {
+		if((p = gettab(f, 0)) == nil || p->run >= 0) {
+			werrstr("first eol");
+			return nil;
+		}
+		f->eol = p;
+		return p;
+	}
+	for(i = 0; (bit = (*f->getbit)(f)) == 0; i++)
+		;
+	if(bit < 0) {
+		f->st = -1;
+		return nil;
+	}
+	if(i < 11) {
+		werrstr("eol");
+		return nil;
+	}
+	return f->eol;
+}
+
+static int
+faxfill(Fax *f, uchar *data, ulong size, ulong *i, ulong *x, ulong dx,
+	int n)
+{
+	if((*x += n) > dx) {
+		werrstr("fax row overflow");
+		return -1;
+	}
+	if((*i += n) >= size) {
+		werrstr("fax data overflow");
+		return -1;
+	}
+	if(f->st != 0)
+		memset(data+*i-n, f->st, n);
+	return 0;
+}
+
+static void
+fillbits(Fax *f)
+{
+	if(f->getbit == getbit1) {
+		if(f->m != 7) {
+			f->n++;
+			f->m = 7;
+		}
+	} else {
+		if(f->m != 0) {
+			f->n++;
+			f->m = 0;
+		}
+	}
+}
+
+static int
+faxalloclines(Fax *f)
+{
+	f->nl *= 2;
+	f->l1 = realloc(f->l1, f->nl*sizeof *f->l1);
+	if(f->l1 == nil)
+		return -1;
+	f->l2 = realloc(f->l2, f->nl*sizeof *f->l2);
+	if(f->l2 == nil) {
+		free(f->l1);
+		return -1;
+	}
+	return 0;
+}
+
+static Tab *
+getfax1d(Fax *f, uchar *data, ulong size, ulong *i, ulong *x,
+	ulong dx)
+{
+	int j, n;
+	Tab *p;
+
+	for(j = 0; *x < dx;) {
+		if((p = gettab(f, 0)) == nil)
+			return nil;
+		if((n = p->run) < 0) {
+			f->l1[j] = dx;
+			return f->eol;
+		}
+		if(faxfill(f, data, size, i, x, dx, n) < 0)
+			return nil;
+		if(n < 64) {
+			f->l1[j++] = *x;
+			f->st ^= 1;
+		}
+		if(j >= f->nl)
+			faxalloclines(f);
+	}
+	return nil;
+}
+
+static Tab *
+getfax2d(Fax *f, uchar *data, ulong size, ulong *i, ulong *x,
+	ulong dx)
+{
+	int j, k, n, code, len, a0, a1, b1, b2, v;
+	Tab *p;
+
+	a0 = -1;
+	for(j = 0; *x < dx;) {
+		for(k = 0;; k++) {
+			b1 = f->l1[k];
+			if(b1 > a0 && f->st == k%2)
+				break;
+			if(b1 >= dx)
+				break;
+		}
+		if((b2 = b1) < dx)
+			b2 = f->l1[k+1];
+		if((p = gettab(f, 1)) == nil)
+			return nil;
+		/* early eofb */
+		if(p->run < 0) {
+			f->st = -1;
+			return nil;
+		}
+		len = p->len;
+		code = p->code;
+		if(code == 1 && len == 3) {
+			/* horizontal */
+			for(k = 0; k < 2;) {
+				if((p = gettab(f, 0)) == nil)
+					return nil;
+				n = p->run;
+				if(faxfill(f, data, size, i, x,
+					dx, n) < 0)
+					return nil;
+				if(n < 64) {
+					f->l2[j++] = *x;
+					f->st ^= 1;
+					k++;
+				}
+			}
+		} else if(code == 1 && len == 4) {
+			/* pass */
+			n = b2 - *x;
+			if(faxfill(f, data, size, i, x, dx, n) < 0)
+				return nil;
+			if(*x == dx)
+				f->l2[j++] = *x;
+		} else {
+			/* vertical */
+			switch(code) {
+			case 1:
+			case 2:
+				v = -vcodeval[len];
+				break;
+			case 3:
+				v = vcodeval[len];
+				break;
+			default:
+				werrstr("mode");
+				return nil;
+			}
+			a1 = b1 + v;
+			n = a1 - *x;
+			if(faxfill(f, data, size, i, x, dx, n) < 0)
+				return nil;
+			f->l2[j++] = *x;
+			f->st ^= 1;
+		}
+		if(j >= f->nl)
+			faxalloclines(f);
+		a0 = *x;
+	}
+	memmove(f->l1, f->l2, j*sizeof *f->l1);
+	return nil;
+}
+
+static int
+faxstrip(Tif *t, Fax *f, uchar *data, ulong size, ulong *i)
+{
+	int d1;
+	ulong x, y;
+	Tab *p;
+
+	d1 = t->comp != T6enc;
+	p = nil;
+	for(x = y = 0; x < t->dx || y < t->rows;) {
+		f->st = 0;
+		if(t->comp == T4enc) {
+			if(p == nil && geteol(f) == nil) {
+				if(f->st >= 0)
+					return -1;
+				break;
+			}
+			if(y > 0)
+				*i += t->dx - x;
+			if(t->t4 & 1) {
+				d1 = (*f->getbit)(f);
+				if(d1 < 0)
+					break;
+			}
+		}
+		x = 0;
+		y++;
+		if(d1) {
+			p = getfax1d(f, data, size, i,
+				&x, t->dx);
+		} else {
+			p = getfax2d(f, data, size, i,
+				&x, t->dx);
+		}
+		if(t->comp == Huffman)
+			fillbits(f);
+		if(p == nil && x != t->dx) {
+			if(f->st >= 0 || x > t->dx)
+				return -1;
+			break;
+		}
+	}
+	return 0;
+}
+
+/*
+* the t4 fax test images i decoded did not follow the
+* spec. in particular, they did not have rtcs.
+*/
+static uchar *
+fax(Tif *t)
+{
+	int m;
+	ulong i, j, datasz, linesz;
+	uchar *data;
+	Fax f;
+
+	datasz = t->dx * t->dy * sizeof *data;
+	data = malloc(datasz);
+	f.nl = t->dx;
+	linesz = f.nl * sizeof *f.l1;
+	f.l1 = malloc(linesz);
+	f.l2 = malloc(linesz);
+	if(data == nil || f.l1 == nil || f.l2 == nil) {
+		free(t->data);
+		if(data != nil)
+			free(data);
+		if(f.l1 != nil)
+			free(f.l1);
+		if(f.l2 != nil)
+			free(f.l2);
+		return nil;
+	}
+	memset(data, 0, datasz);
+	memset(f.l1, 0, linesz);
+	memset(f.l2, 0, linesz);
+	if(t->fill == 1) {
+		f.getbit = getbit1;
+		m = 7;
+	} else {
+		f.getbit = getbit2;
+		m = 0;
+	}
+	f.tab[0] = faxwhite;
+	f.tab[1] = faxblack;
+	f.ntab = 0;
+	f.eol = nil;
+	f.data = t->data;
+	for(i = j = 0; i < t->nstrips; i++) {
+		f.l1[0] = t->dx;
+		f.n = t->strips[i];
+		f.m = m;
+		if(i < t->nstrips-1)
+			f.next = t->strips[i+1];
+		else
+			f.next = t->ndata;
+		if(faxstrip(t, &f, data, datasz, &j) < 0)
+			break;
+	}
+	if(i < t->nstrips) {
+		free(data);
+		data = nil;
+	}
+	free(t->data);
+	free(f.l1);
+	free(f.l2);
+	return data;
+}
+
+static void
+tabinit(Lzw *l)
+{
+	l->ntab = Eoicode + 1;
+	l->len = 9;
+}
+
+static Code *
+newcode(Lzw *l, Code *p)
+{
+	Code *q;
+
+	if(p == nil)
+		return nil;
+	if(l->first != nil) {
+		q = l->first;
+		if((l->first = l->first->next) == nil)
+			l->last = nil;
+	} else if((q = malloc(sizeof *q)) == nil)
+		return nil;
+	q->val = p->val;
+	q->next = nil;
+	return q;
+}
+
+static void
+listadd(Lzw *l, Code *p)
+{
+	if(p == nil)
+		return;
+	if(l->last != nil)
+		l->last->next = p;
+	else
+		l->first = l->last = p;
+	while(l->last->next != nil)
+		l->last = l->last->next;
+}
+
+static Code *
+tabadd(Lzw *l, Code *p, Code *q)
+{
+	Code *r, *s;
+
+	if(l->ntab >= Tabsz) {
+		werrstr("lzw table full");
+		return nil;
+	}
+	r = s = &l->tab[l->ntab++];
+	switch(l->ntab) {
+	case 511:
+	case 1023:
+	case 2047:
+		l->len++;
+		break;
+	default:
+		break;
+	}
+	s->val = p->val;
+	while((p = p->next) != nil) {
+		if(s->next != nil)
+			s->next->val = p->val;
+		else if((s->next = newcode(l, p)) == nil)
+			return nil;
+		s = s->next;
+	}
+	if(s->next != nil) {
+		s->next->val = q->val;
+		s = s->next;
+		if(s->next != nil) {
+			listadd(l, s->next);
+			s->next = nil;
+		}
+	} else if((s->next = newcode(l, q)) == nil)
+		return nil;
+	return r;
+}
+
+static int
+getcode(Lzw *l)
+{
+	int i, c, code;
+
+	if(l->n >= l->next) {
+		werrstr("lzw eof");
+		return -1;
+	}
+	code = 0;
+	for(i = l->len-1; i >= 0; i--) {
+		c = (l->data[l->n] >> l->m) & 0x1;
+		code |= c << i;
+		l->m--;
+		if(l->m < 0) {
+			l->n++;
+			l->m = 7;
+		}
+	}
+	return code;
+}
+
+static int
+wstr(uchar *data, ulong size, ulong *i, Code *p, long *striplen)
+{
+	for(; p != nil; p = p->next, ++*i, --*striplen) {
+		if(*i >= size || *striplen < 0) {
+			werrstr("lzw overflow");
+			return -1;
+		}
+		data[*i] = p->val;
+	}
+	return 0;
+}
+
+static void
+predict(Tif *t, uchar *data)
+{
+	char a, b;
+	ulong y, x, i, j, k, s;
+
+	s = t->samples;
+	for(y = 0; y < t->dy; y++) {
+		for(x = 1; x < t->dx; x++) {
+			i = y*t->dx + x;
+			for(j = 0; j < s; j++) {
+				k = i*s + j;
+				a = (char)data[k];
+				b = (char)data[k-s];
+				data[k] = (uchar)(a + b);
+			}
+		}
+	}
+}
+
+static int
+lzwstrip(Lzw *l, uchar *data, ulong size, ulong *i, long striplen)
+{
+	int c, oc;
+	Code *p, *q;
+
+	if((c = getcode(l)) != Clrcode) {
+		werrstr("clear code");
+		return -1;
+	}
+	for(oc = -1; c != Eoicode;) {
+		if(c < 0)
+			return -1;
+		if(c == Clrcode) {
+			if(oc >= 0)
+				tabinit(l);
+			if((c = getcode(l)) == Eoicode)
+				break;
+			if(c < 0)
+				return -1;
+			if(wstr(data, size, i, &l->tab[c],
+				&striplen) < 0)
+				return -1;
+		} else if(c < l->ntab) {
+			p = &l->tab[c];
+			if(wstr(data, size, i, p,
+				&striplen) < 0)
+				return -1;
+			q = &l->tab[oc];
+			if(tabadd(l, q, p) == nil)
+				return -1;
+		} else {
+			q = &l->tab[oc];
+			if((p = tabadd(l, q, q)) == nil)
+				return -1;
+			if(wstr(data, size, i, p,
+				&striplen) < 0)
+				return -1;
+		}
+		if(striplen <= 0)
+			break;
+		oc = c;
+		c = getcode(l);
+	}
+	return 0;
+}
+
+static uchar *
+lzw(Tif *t)
+{
+	ulong i, j, size;
+	long striplen;
+	uchar *data;
+	Lzw l;
+	Code *p, *q;
+
+	i = t->dx * t->rows * t->depth;
+	striplen = i%8 == 0? i/8: i/8+1;
+	size = t->nstrips * striplen * sizeof *data;
+	if((data = malloc(size)) == nil) {
+		free(t->data);
+		return nil;
+	}
+	for(i = 0; i < Tabsz; i++) {
+		l.tab[i].val = i;
+		l.tab[i].next = nil;
+	}
+	l.data = t->data;
+	l.first = l.last = nil;
+	for(i = j = 0; i < t->nstrips; i++) {
+		tabinit(&l);
+		l.n = t->strips[i];
+		l.m = 7;
+		if(i < t->nstrips-1)
+			l.next = t->strips[i+1];
+		else
+			l.next = t->ndata;
+		if(lzwstrip(&l, data, size, &j, striplen) < 0)
+			break;
+	}
+	if(i < t->nstrips) {
+		free(data);
+		data = nil;
+	}
+	for(i = 0; i < Tabsz; i++) {
+		for(p = l.tab[i].next; (q = p) != nil;) {
+			p = p->next;
+			free(q);
+		}
+	}
+	for(p = l.first; (q = p) != nil;) {
+		p = p->next;
+		free(q);
+	}
+	free(t->data);
+	if(data != nil && t->predictor == 2)
+		predict(t, data);
+	return data;
+}
+
+static uchar *
+packbits(Tif *t)
+{
+	char n;
+	ulong i, j, k, size;
+	uchar *data;
+
+	size = t->dx * t->dy * t->samples * sizeof *data;
+	if((data = malloc(size)) == nil) {
+		free(t->data);
+		return nil;
+	}
+	for(i = 0, j = 0; i < t->ndata;) {
+		n = (char)t->data[i++];
+		if(n >= 0) {
+			k = n + 1;
+			if(j+k >= size || i+k >= t->ndata)
+				break;
+			memmove(data+j, t->data+i, k);
+			i += k;
+			j += k;
+		} else if(n > -128 && n < 0) {
+			k = j - n + 1;
+			if(k > size || i >= t->ndata)
+				break;
+			for(; j < k; j++)
+				data[j] = t->data[i];
+			i++;
+		}
+	}
+	if(i < t->ndata) {
+		werrstr("packbits overflow");
+		free(data);
+		data = nil;
+	}
+	free(t->data);
+	return data;
+}
+
+static int
+faxdecode(Tif *t, Rawimage *im, uchar *data)
+{
+	ulong n;
+
+	for(n = 0; n < im->chanlen; n++) {
+		if(t->photo == Whitezero)
+			data[n] ^= 1;
+		im->chans[0][n] = data[n] * 0xff;
+	}
+	return 0;
+}
+
+static int
+greydecode(Tif *t, Rawimage *im, uchar *data)
+{
+	int pix, pmask, xmask;
+	ulong i, n, x, y;
+
+	pmask = (1 << t->depth) - 1;
+	xmask = 7 >> log2[t->depth];
+	for(y = 0, n = 0; y < t->dy; y++) {
+		i = y * bytesperline(im->r, t->depth);
+		for(x = 0; x < t->dx; x++, n++) {
+			if(n >= im->chanlen) {
+				werrstr("grey overflow");
+				return -1;
+			}
+			pix = (data[i] >> t->depth*((xmask -
+				x) & xmask)) & pmask;
+			if(((x + 1) & xmask) == 0)
+				i++;
+			if(t->photo == Whitezero)
+				pix ^= pmask;
+			pix = (pix * 0xff) / pmask;
+			im->chans[0][n] = pix;
+		}
+	}
+	return 0;
+}
+
+static int
+rgbdecode(Tif *t, Rawimage *im, uchar *data)
+{
+	ulong i, n, x, y;
+
+	for(y = 0, n = 0; y < t->dy; y++) {
+		for(x = 0; x < t->dx; x++, n += 3) {
+			if(n >= im->chanlen) {
+				werrstr("rgb overflow");
+				return -1;
+			}
+			i = (y*t->dx + x) * 3;
+			im->chans[0][n] = data[i+2];
+			im->chans[0][n+1] = data[i+1];
+			im->chans[0][n+2] = data[i];
+		}
+	}
+	return 0;
+}
+
+static int
+paldecode(Tif *t, Rawimage *im, uchar *data)
+{
+	int pix, pmask, xmask;
+	ulong i, n, x, y, *r, *g, *b;
+
+	pmask = (1 << t->depth) - 1;
+	xmask = 7 >> log2[t->depth];
+	r = t->color;
+	g = r + pmask + 1;
+	b = g + pmask + 1;
+	for(y = 0, n = 0; y < t->dy; y++) {
+		i = y * bytesperline(im->r, t->depth);
+		for(x = 0; x < t->dx; x++, n += 3) {
+			if(n >= im->chanlen) {
+				werrstr("palette overflow");
+				return -1;
+			}
+			pix = (data[i] >> t->depth*((xmask -
+				x) & xmask)) & pmask;
+			if(((x + 1) & xmask) == 0)
+				i++;
+			im->chans[0][n] = b[pix];
+			im->chans[0][n+1] = g[pix];
+			im->chans[0][n+2] = r[pix];
+		}
+	}
+	return 0;
+}
+
+static int
+parsefield(Tif *t, Fld *f)
+{
+	ulong v;
+
+	v = f->val[0];
+	switch(f->tag) {
+	case Width:
+		t->dx = v;
+		break;
+	case Length:
+		t->dy = v;
+		break;
+	case Bits:
+		t->depth = v;
+		if(f->cnt == 3)
+			t->depth += f->val[1] + f->val[2];
+		break;
+	case Compression:
+		t->comp = v;
+		break;
+	case Photometric:
+		t->photo = v;
+		switch(t->photo) {
+		case Whitezero:
+		case Blackzero:
+			t->decode = greydecode;
+			break;
+		case Rgb:
+			t->decode = rgbdecode;
+			break;
+		case Palette:
+			t->decode = paldecode;
+			break;
+		default:
+			break;
+		}
+		break;
+	case Strips:
+		t->strips = f->val;
+		t->nstrips = f->cnt;
+		break;
+	case Fill:
+		t->fill = v;
+		break;
+	case Orientation:
+		t->orientation = v;
+		break;
+	case Samples:
+		t->samples = v;
+		break;
+	case Rows:
+		t->rows = v;
+		break;
+	case Counts:
+		t->counts = f->val;
+		t->ncounts = f->cnt;
+		break;
+	case Planar:
+		t->planar = v;
+		break;
+	case T4opts:
+		t->t4 = v;
+		break;
+	case T6opts:
+		t->t6 = v;
+		break;
+	case Predictor:
+		t->predictor = v;
+		break;
+	case Color:
+		t->color = f->val;
+		t->ncolor = f->cnt;
+		break;
+	default:
+		werrstr("shouldn't reach");
+		return -1;
+	}
+	return 0;
+}
+
+static int
+readfield(Tif *t, Fld *f)
+{
+	int size;
+	ulong i, j, n, off;
+	ulong (*readval)(Tif *);
+
+	f->tag = readshort(t);
+	f->typ = readshort(t);
+	f->cnt = readlong(t);
+	f->val = nil;
+	switch(f->tag) {
+	case Width:
+	case Length:
+	case Compression:
+	case Photometric:
+	case Fill:
+	case Orientation:
+	case Samples:
+	case Rows:
+	case Planar:
+	case T4opts:
+	case T6opts:
+	case Predictor:
+		if(f->cnt != 1) {
+			werrstr("field count");
+			return -1;
+		}
+		break;
+	case Bits:
+		if(f->cnt != 1 && f->cnt != 3) {
+			werrstr("field count");
+			return -1;
+		}
+		break;
+	case Strips:
+	case Counts:
+	case Color:
+		break;
+	default:
+		readlong(t);
+		return 0;
+	}
+	switch(f->typ) {
+	case Byte:
+		readval = readbyte;
+		break;
+	case Short:
+		readval = readshort;
+		break;
+	case Long:
+		readval = readlong;
+		break;
+	default:
+		werrstr("unsupported type\n");
+		return -1;
+	}
+	if((f->val = malloc(f->cnt*sizeof *f->val)) == nil)
+		return -1;
+	size = typesizes[f->typ];
+	if((n = size*f->cnt) <= 4) {
+		for(i = 0; i < f->cnt; i++)
+			f->val[i] = readval(t);
+		f->off = 0x0;
+		f->nval = i;
+		for(j = n; j < 4; j += size)
+			readval(t);
+	} else {
+		f->off = readlong(t);
+		off = t->n;
+		if(gototif(t, f->off) < 0)
+			return -1;
+		for(i = 0; i < f->cnt; i++)
+			f->val[i] = readval(t);
+		f->nval = i;
+		if(gototif(t, off) < 0)
+			return -1;
+	}
+	return parsefield(t, f);
+}
+
+static int
+checkfields(Tif *t)
+{
+	double a, b;
+	ulong n, size;
+
+	if(t->dx == 0) {
+		werrstr("image width");
+		return -1;
+	}
+	if(t->dy == 0) {
+		werrstr("image length");
+		return -1;
+	}
+	switch(t->depth) {
+	case 1:
+	case 4:
+	case 8:
+	case 24:
+		break;
+	default:
+		werrstr("bits per sample");
+		return -1;
+	}
+	switch(t->comp) {
+	case Nocomp:
+		t->uncompress = nocomp;
+		break;
+	case Huffman:
+	case T4enc:
+	case T6enc:
+		t->uncompress = fax;
+		if(t->decode != nil)
+			t->decode = faxdecode;
+		if((t->comp == T4enc && t->t4 & (1<<1)) ||
+			(t->comp == T6enc &&
+			t->t6 & (1<<1))) {
+			werrstr("uncompressed mode");
+			return -1;
+		}
+		break;
+	case Lzwenc:
+		t->uncompress = lzw;
+		break;
+	case Packbits:
+		t->uncompress = packbits;
+		break;
+	default:
+		werrstr("compression");
+		return -1;
+	}
+	if(t->decode == nil) {
+		werrstr("photometric interpretation");
+		return -1;
+	}
+	if(t->depth > 1 && (t->comp == Huffman ||
+		t->comp == T4enc || t->comp == T6enc)) {
+		werrstr("compression");
+		return -1;
+	}
+	if(t->fill != 1 && t->fill != 2) {
+		werrstr("fill order");
+		return -1;
+	}
+	if(t->fill == 2 && t->depth != 1) {
+		werrstr("depth should be 1 with fill order 2");
+		return -1;
+	}
+	if(t->orientation != 1) {
+		werrstr("orientation");
+		return -1;
+	}
+	if(t->rows == 0) {
+		werrstr("rows per strip");
+		return -1;
+	}
+	a = (double)t->dy;
+	b = (double)t->rows;
+	n = (ulong)floor((a+b-1)/b);
+	if(t->strips == nil || t->nstrips != n) {
+		werrstr("strip offsets");
+		return -1;
+	}
+	if(t->samples == 1 && t->photo == Rgb) {
+		werrstr("not enough samples per pixel");
+		return -1;
+	}
+	if(t->samples == 3 && t->photo != Rgb) {
+		werrstr("too many samples per pixel");
+		return -1;
+	}
+	if(t->samples != 1 && t->samples != 3) {
+		werrstr("samples per pixel");
+		return -1;
+	}
+	/*
+	* strip byte counts should not be missing,
+	* but we can guess correctly in this case
+	*/
+	size = sizeof *t->counts;
+	if(t->counts == nil && t->comp == Nocomp &&
+		t->nstrips == 1 &&
+		(t->counts = malloc(size)) != nil) {
+		n = t->dx * t->dy * t->depth;
+		t->counts[0] = n%8 == 0? n/8: n/8+1;
+		t->ncounts = t->nstrips;
+	}
+	if(t->counts == nil || t->ncounts != t->nstrips) {
+		werrstr("strip byte counts");
+		return -1;
+	}
+	if(t->planar != 1) {
+		werrstr("planar configuration");
+		return -1;
+	}
+	if(t->photo == Palette && (t->color == nil ||
+		t->ncolor != 3*(1<<t->depth))) {
+		werrstr("color map");
+		return -1;
+	}
+	if(t->predictor == 2 && t->depth == 1) {
+		werrstr("depth too low for predictor 2");
+		return -1;
+	}
+	return 0;
+}
+
+static int
+readstrips(Tif *t)
+{
+	int i, j, n;
+	ulong off;
+
+	t->ndata = 0;
+	for(i = 0; i < t->nstrips; i++)
+		t->ndata += t->counts[i];
+	if((t->data = malloc(t->ndata*sizeof *t->data)) == nil)
+		return -1;
+	off = t->n;
+	for(i = n = 0; i < t->nstrips; i++) {
+		if(gototif(t, t->strips[i]) < 0)
+			return -1;
+		/*
+		* we store each strip's offset in t->data
+		* in order to skip the final rtc or eofb
+		* during fax decoding. t->strips is used
+		* to save on memory allocation. these
+		* offsets are also used in lzw as a
+		* preventive measure.
+		*/
+		t->strips[i] = n;
+		for(j = 0; j < t->counts[i]; j++, n++)
+			t->data[n] = readbyte(t);
+	}
+	return gototif(t, off);
+}
+
+static Rawimage *
+decode(Tif *t)
+{
+	ulong size;
+	uchar *data;
+	Rawimage *im;
+
+	if((im = malloc(sizeof *im)) == nil)
+		return nil;
+	im->r = Rect(0, 0, t->dx, t->dy);
+	im->cmap = nil;
+	im->cmaplen = 0;
+	im->chanlen = t->dx * t->dy;
+	if(t->photo == Rgb || t->photo == Palette) {
+		im->chandesc = CRGB24;
+		im->chanlen *= 3;
+	} else
+		im->chandesc = CY;
+	im->nchans = 1;
+	size = im->chanlen * sizeof *im->chans[0];
+	if((im->chans[0] = malloc(size)) == nil)
+		return nil;
+	/* unused members */
+	im->fields = 0;
+	im->gifflags = 0;
+	im->gifdelay = 0;
+	im->giftrindex = 0;
+	im->gifloopcount = 1;
+	if((data = (*t->uncompress)(t)) == nil)
+		return nil;
+	if((*t->decode)(t, im, data) < 0) {
+		free(im->chans[0]);
+		free(im);
+		im = nil;
+	}
+	free(data);
+	return im;
+}
+
+static void
+freefields(Tif *t)
+{
+	uint i;
+
+	for(i = 0; i < t->nfld; i++) {
+		if(t->fld[i].val != nil)
+			free(t->fld[i].val);
+	}
+	free(t->fld);
+}
+
+static Rawimage *
+readslave(Tif *t)
+{
+	uint i, j;
+	Rawimage *r;
+
+	if(readheader(t) < 0)
+		return nil;
+	if((t->nfld = readshort(t)) <= 0) {
+		werrstr("illegal field number: %#.4x", t->nfld);
+		return nil;
+	}
+	if((t->fld = malloc(t->nfld*sizeof *t->fld)) == nil)
+		return nil;
+	for(i = 0; i < t->nfld; i++) {
+		if(readfield(t, &t->fld[i]) < 0) {
+			if(t->fld[i].val != nil)
+				free(t->fld[i].val);
+			break;
+		}
+	}
+	if(i < t->nfld) {
+		for(j = 0; j < i; j++) {
+			if(t->fld[j].val != nil)
+				free(t->fld[j].val);
+		}
+		free(t->fld);
+		return nil;
+	}
+	readlong(t);
+	if(checkfields(t) < 0) {
+		freefields(t);
+		return nil;
+	}
+	if(readstrips(t) < 0) {
+		freefields(t);
+		if(t->data != nil)
+			free(t->data);
+		return nil;
+	}
+	free(t->buf);
+	r = decode(t);
+	freefields(t);
+	return r;
+}
+
+Rawimage **
+Breadtif(Biobuf *b)
+{
+	Rawimage **array, *r;
+	Tif *t;
+
+	if((t = malloc(sizeof *t)) == nil)
+		return nil;
+	if((array = malloc(2*sizeof *array)) == nil)
+		return nil;
+	t->fd = b;
+	t->buf = nil;
+	t->nbuf = t->eof = t->n = 0;
+	/* order doesn't matter for the first two bytes */
+	t->byte2 = byte2le;
+	t->byte4 = byte4le;
+	/* defaults */
+	t->dx = 0;
+	t->dy = 0;
+	t->depth = 1;
+	t->comp = 1;
+	t->uncompress = nil;
+	t->photo = 0;
+	t->decode = nil;
+	t->fill = 1;
+	t->orientation = 1;
+	t->strips = nil;
+	t->nstrips = 0;
+	t->samples = 1;
+	t->rows = 0xffffffff; /* entire image is one strip */
+	t->counts = nil;
+	t->ncounts = 0;
+	t->planar = 1;
+	t->t4 = 0;
+	t->t6 = 0;
+	t->predictor = 1;
+	t->color = nil;
+	t->ncolor = 0;
+	r = readslave(t);
+	free(t);
+	array[0] = r;
+	array[1] = nil;
+	return array;
+}
+
+Rawimage **
+readtif(int fd)
+{
+	Rawimage **a;
+	Biobuf b;
+
+	if(Binit(&b, fd, OREAD) < 0)
+		return nil;
+	a = Breadtif(&b);
+	Bterm(&b);
+	return a;
+}
diff --git a/sys/src/cmd/jpg/tif.c b/sys/src/cmd/jpg/tif.c
new file mode 100644
index 000000000..6607efb93
--- /dev/null
+++ b/sys/src/cmd/jpg/tif.c
@@ -0,0 +1,251 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <draw.h>
+#include <event.h>
+#include "imagefile.h"
+
+int cflag = 0;
+int dflag = 0;
+int eflag = 0;
+int nineflag = 0;
+int threeflag = 0;
+int output = 0;
+Image *image;
+int defaultcolor = 1;
+
+enum {
+	Border = 2,
+	Edge = 5
+};
+
+int init(void);
+char *show(int, char *, int);
+
+void
+eresized(int new)
+{
+	Rectangle r;
+
+	if(new && getwindow(display, Refnone) < 0)
+		sysfatal("getwindow: %r");
+	if(image == nil)
+		return;
+	r = insetrect(screen->clipr, Edge+Border);
+	r.max.x = r.min.x + Dx(image->r);
+	r.max.y = r.min.y + Dy(image->r);
+	border(screen, r, -Border, nil, ZP);
+	drawop(screen, r, image, nil, image->r.min, S);
+	flushimage(display, 1);
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s [-39cdektv] [file.tif ...]\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	int fd, i;
+	char *err;
+	ulong outchan;
+
+	outchan = CMAP8;
+	ARGBEGIN {
+	/*
+	* produce encoded, compressed, bitmap file;
+	* no display by default
+	*/
+	case 'c':
+		cflag++;
+		dflag++;
+		output++;
+		if(defaultcolor)
+			outchan = CMAP8;
+		break;
+	/* suppress display of image */
+	case 'd':
+		dflag++;
+		break;
+	/* disable floyd-steinberg error diffusion */
+	case 'e':
+		eflag++;
+		break;
+	/* force black and white */
+	case 'k':
+		defaultcolor = 0;
+		outchan = GREY8;
+		break;
+	/*
+	* produce encoded, compressed, three-color
+	* bitmap file; no display by default
+	*/
+	case '3':
+		threeflag++;
+		/* fall through */
+	/*
+	* produce encoded, compressed, true-color
+	* bitmap file; no display by default
+	*/
+	case 't':
+		cflag++;
+		dflag++;
+		output++;
+		defaultcolor = 0;
+		outchan = RGB24;
+		break;
+	/* force RGBV */
+	case 'v':
+		defaultcolor = 0;
+		outchan = CMAP8;
+		break;
+	/*
+	* produce plan 9, uncompressed, bitmap file;
+	* no display by default
+	*/
+	case '9':
+		nineflag++;
+		dflag++;
+		output++;
+		if(defaultcolor)
+			outchan = CMAP8;
+		break;
+	default:
+		usage();
+	} ARGEND
+
+	if(argc <= 0)
+		exits(show(0, "<stdin>", outchan));
+	err = nil;
+	for(i = 0; i < argc; i++) {
+		if((fd = open(argv[i], OREAD)) < 0) {
+			fprint(2, "%s: open %s: %r\n",
+				argv0, argv[i]);
+			err = "open";
+		} else {
+			err = show(fd, argv[i], outchan);
+			close(fd);
+		}
+		if((nineflag || cflag) && argc > 1 && err == nil) {
+			fprint(2, "%s: exiting after one file\n",
+				argv0);
+			break;
+		}
+	}
+	exits(err);
+}
+
+int
+init(void)
+{
+	static int inited = 0;
+
+	if(!inited) {
+		if(initdraw(0, 0, 0) < 0) {
+			fprint(2, "%s: initdraw: %r", argv0);
+			return -1;
+		}
+		einit(Ekeyboard|Emouse);
+		inited++;
+	}
+	return 0;
+}
+
+char *
+show(int fd, char *name, int outchan)
+{
+	Rawimage **array, *r, *c;
+	Image *i;
+	int j, ch;
+	Biobuf b;
+	char buf[32];
+
+	if(Binit(&b, fd, OREAD) < 0)
+		return nil;
+	array = Breadtif(&b);
+	if(array == nil || array[0] == nil) {
+		if(array != nil)
+			free(array);
+		fprint(2, "%s: decode %s failed: %r\n", argv0,
+			name);
+		return "decode";
+	}
+	Bterm(&b);
+	if(!dflag) {
+		if(init() < 0)
+			return "initdraw";
+/* fixme: ppm doesn't check for outchan==CMAP8 */
+		if(defaultcolor && screen->depth > 8 &&
+			outchan == CMAP8)
+			outchan = RGB24;
+	}
+	r = array[0];
+	if(outchan != CMAP8) {
+		switch(r->chandesc) {
+		case CY:
+			outchan = GREY8;
+			break;
+		case CRGB24:
+			outchan = RGB24;
+			break;
+		}
+		c = r;
+	} else if((c = torgbv(r, !eflag)) == nil) {
+		fprint(2, "%s: conversion of %s failed: %r\n",
+			argv0, name);
+		return "torgbv";
+	}
+	if(!dflag) {
+		i = allocimage(display, c->r, outchan, 0, 0);
+		if(i == nil) {
+			fprint(2, "%s: allocimage %s: %r\n",
+				argv0, name);
+			return "allocimage";
+		}
+		if(loadimage(i, i->r, c->chans[0],
+			c->chanlen) < 0) {
+			fprint(2, "%s: loadimage %s: %r\n",
+				argv0, name);
+			return "loadimage";
+		}
+		image = i;
+		eresized(0);
+		ch = ekbd();
+		if(ch == 'q' || ch == 0x7f || ch == 0x04)
+			exits(nil);
+		draw(screen, screen->clipr, display->white,
+			nil, ZP);
+		image = nil;
+		freeimage(i);
+	}
+	if(nineflag) {
+		chantostr(buf, outchan);
+		print("%11s %11d %11d %11d %11d ", buf,
+			c->r.min.x, c->r.min.y,
+			c->r.max.x, c->r.max.y);
+		if(write(1, c->chans[0], c->chanlen) !=
+			c->chanlen) {
+			fprint(2, "%s: %s: write error: %r\n",
+				argv0, name);
+			return "write";
+		}
+	} else if(cflag) {
+		if(writerawimage(1, c) < 0) {
+			fprint(2, "%s: %s: write error: %r\n",
+				argv0, name);
+			return "write";
+		}
+	}
+	if(c != nil && c != r) {
+		free(c->chans[0]);
+		free(c);
+	}
+	for(j = 0; j < r->nchans; j++)
+		free(r->chans[j]);
+	free(r);
+	free(array);
+	return nil;
+}
diff --git a/sys/src/cmd/page.c b/sys/src/cmd/page.c
index 0926b8486..aea34facd 100644
--- a/sys/src/cmd/page.c
+++ b/sys/src/cmd/page.c
@@ -680,6 +680,7 @@ popenfile(Page *p)
 	"image/gif",			popenimg,	"gif",
 	"image/jpeg",			popenimg,	"jpg",
 	"image/png",			popenimg,	"png",
+	"image/tiff",			popenimg,	"tif",
 	"image/ppm",			popenimg,	"ppm",
 	"image/bmp",			popenimg,	"bmp",
 	"image/tga",			popenimg,	"tga",