diff --git a/libtests/build.mk b/libtests/build.mk
index baa3412..4579241 100644
--- a/libtests/build.mk
+++ b/libtests/build.mk
@@ -11,8 +11,8 @@ BINS_libtests = \
 	input_source \
 	lzw \
 	md5 \
-	png_filter \
 	pointer_holder \
+	predictors \
 	qutil \
 	random \
 	rc4 \
diff --git a/libtests/png_filter.cc b/libtests/predictors.cc
index 7494cb7..fe2b90f 100644
--- a/libtests/png_filter.cc
+++ b/libtests/predictors.cc
@@ -8,17 +8,26 @@
 #include <string.h>
 #include <stdlib.h>
 
-void run(char const* filename, bool encode, unsigned int columns,
+void run(char const* filename, char const* filter,
+         bool encode, unsigned int columns,
          int bits_per_sample, int samples_per_pixel)
 {
-    // Decode the file
     FILE* in = QUtil::safe_fopen(filename, "rb");
     FILE* o1 = QUtil::safe_fopen("out", "wb");
     Pipeline* out = new Pl_StdioFile("out", o1);
-    Pipeline* pl = new Pl_PNGFilter(
-	"png", out,
-	encode ? Pl_PNGFilter::a_encode : Pl_PNGFilter::a_decode,
-	columns, samples_per_pixel, bits_per_sample);
+    Pipeline* pl = 0;
+    if (strcmp(filter, "png") == 0)
+    {
+        pl = new Pl_PNGFilter(
+            "png", out,
+            encode ? Pl_PNGFilter::a_encode : Pl_PNGFilter::a_decode,
+            columns, samples_per_pixel, bits_per_sample);
+    }
+    else
+    {
+        std::cerr << "unknown filter " << filter << std::endl;
+        exit(2);
+    }
     assert((2 * (columns + 1)) < 1024);
     unsigned char buf[1024];
     size_t len;
@@ -55,22 +64,24 @@ void run(char const* filename, bool encode, unsigned int columns,
 
 int main(int argc, char* argv[])
 {
-    if (argc != 6)
+    if (argc != 7)
     {
-	std::cerr << "Usage: png_filter {en,de}code filename"
+	std::cerr << "Usage: predictor {png|tiff} {en,de}code filename"
                   << " columns samples-per-pixel bits-per-sample"
                   << std::endl;
 	exit(2);
     }
-    bool encode = (strcmp(argv[1], "encode") == 0);
-    char* filename = argv[2];
-    int columns = QUtil::string_to_int(argv[3]);
-    int samples_per_pixel = QUtil::string_to_int(argv[4]);
-    int bits_per_sample = QUtil::string_to_int(argv[5]);
+    char* filter = argv[1];
+    bool encode = (strcmp(argv[2], "encode") == 0);
+    char* filename = argv[3];
+    int columns = QUtil::string_to_int(argv[4]);
+    int samples_per_pixel = QUtil::string_to_int(argv[5]);
+    int bits_per_sample = QUtil::string_to_int(argv[6]);
 
     try
     {
-	run(filename, encode, columns, bits_per_sample, samples_per_pixel);
+	run(filename, filter, encode,
+            columns, bits_per_sample, samples_per_pixel);
     }
     catch (std::exception& e)
     {
diff --git a/libtests/qtest/png_filter.test b/libtests/qtest/predictors.test
index ff3cef5..f055347 100644
--- a/libtests/qtest/png_filter.test
+++ b/libtests/qtest/predictors.test
@@ -5,16 +5,16 @@ use strict;
 use File::Copy;
 use Digest::MD5;
 
-chdir("png_filter") or die "chdir testdir failed: $!\n";
+chdir("predictors") or die "chdir testdir failed: $!\n";
 
 require TestDriver;
 
-my $td = new TestDriver('png_filter');
+my $td = new TestDriver('predictors');
 
 cleanup();
 
 $td->runtest("decode columns = 4",
-	     {$td->COMMAND => "png_filter decode in1 4 1 8"},
+	     {$td->COMMAND => "predictors png decode in1 4 1 8"},
 	     {$td->STRING => "done\n",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
@@ -24,7 +24,7 @@ $td->runtest("check output",
 	     {$td->FILE => "out1"});
 
 $td->runtest("decode columns = 5",
-	     {$td->COMMAND => "png_filter decode in2 5 1 8"},
+	     {$td->COMMAND => "predictors png decode in2 5 1 8"},
 	     {$td->STRING => "done\n",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
@@ -34,7 +34,7 @@ $td->runtest("check output",
 	     {$td->FILE => "out2"});
 
 $td->runtest("encode columns = 4",
-	     {$td->COMMAND => "png_filter encode out1 4 1 8"},
+	     {$td->COMMAND => "predictors png encode out1 4 1 8"},
 	     {$td->STRING => "done\n",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
@@ -44,7 +44,7 @@ $td->runtest("check output",
 	     {$td->FILE => "in1"});
 
 $td->runtest("encode columns = 5",
-	     {$td->COMMAND => "png_filter encode out2 5 1 8"},
+	     {$td->COMMAND => "predictors png encode out2 5 1 8"},
 	     {$td->STRING => "done\n",
 	      $td->EXIT_STATUS => 0},
 	     $td->NORMALIZE_NEWLINES);
@@ -75,7 +75,7 @@ foreach my $i (@other)
     my $samples_per_pixel = $2;
     my $bits_per_sample = $3;
     $td->runtest("decode $i",
-                 {$td->COMMAND => "png_filter decode $i.data" .
+                 {$td->COMMAND => "predictors png decode $i.data" .
                       " $columns $samples_per_pixel $bits_per_sample"},
                  {$td->STRING => "done\n",
                       $td->EXIT_STATUS => 0},
diff --git a/libtests/qtest/png_filter/01--32-3-16.data b/libtests/qtest/predictors/01--32-3-16.data
index 01cfcbc..01cfcbc 100644
--- a/libtests/qtest/png_filter/01--32-3-16.data
+++ b/libtests/qtest/predictors/01--32-3-16.data
diff --git a/libtests/qtest/png_filter/01--32-3-16.decoded b/libtests/qtest/predictors/01--32-3-16.decoded
index 2459a08..2459a08 100644
--- a/libtests/qtest/png_filter/01--32-3-16.decoded
+++ b/libtests/qtest/predictors/01--32-3-16.decoded
diff --git a/libtests/qtest/png_filter/02--32-1-8.data b/libtests/qtest/predictors/02--32-1-8.data
index c7978ff..c7978ff 100644
--- a/libtests/qtest/png_filter/02--32-1-8.data
+++ b/libtests/qtest/predictors/02--32-1-8.data
diff --git a/libtests/qtest/png_filter/02--32-1-8.decoded b/libtests/qtest/predictors/02--32-1-8.decoded
index d8320b3..d8320b3 100644
--- a/libtests/qtest/png_filter/02--32-1-8.decoded
+++ b/libtests/qtest/predictors/02--32-1-8.decoded
diff --git a/libtests/qtest/png_filter/03--32-3-8.data b/libtests/qtest/predictors/03--32-3-8.data
index 5600cc4..5600cc4 100644
--- a/libtests/qtest/png_filter/03--32-3-8.data
+++ b/libtests/qtest/predictors/03--32-3-8.data
diff --git a/libtests/qtest/png_filter/03--32-3-8.decoded b/libtests/qtest/predictors/03--32-3-8.decoded
index ae56281..ae56281 100644
--- a/libtests/qtest/png_filter/03--32-3-8.decoded
+++ b/libtests/qtest/predictors/03--32-3-8.decoded
diff --git a/libtests/qtest/png_filter/04--32-1-8.data b/libtests/qtest/predictors/04--32-1-8.data
index 684a649..684a649 100644
--- a/libtests/qtest/png_filter/04--32-1-8.data
+++ b/libtests/qtest/predictors/04--32-1-8.data
diff --git a/libtests/qtest/png_filter/04--32-1-8.decoded b/libtests/qtest/predictors/04--32-1-8.decoded
index e1087d1..e1087d1 100644
--- a/libtests/qtest/png_filter/04--32-1-8.decoded
+++ b/libtests/qtest/predictors/04--32-1-8.decoded
diff --git a/libtests/qtest/png_filter/05--32-3-8.data b/libtests/qtest/predictors/05--32-3-8.data
index 32c103f..32c103f 100644
--- a/libtests/qtest/png_filter/05--32-3-8.data
+++ b/libtests/qtest/predictors/05--32-3-8.data
diff --git a/libtests/qtest/png_filter/05--32-3-8.decoded b/libtests/qtest/predictors/05--32-3-8.decoded
index f4a4f7c..f4a4f7c 100644
--- a/libtests/qtest/png_filter/05--32-3-8.decoded
+++ b/libtests/qtest/predictors/05--32-3-8.decoded
diff --git a/libtests/qtest/png_filter/06--32-1-8.data b/libtests/qtest/predictors/06--32-1-8.data
index 806f68e..806f68e 100644
--- a/libtests/qtest/png_filter/06--32-1-8.data
+++ b/libtests/qtest/predictors/06--32-1-8.data
diff --git a/libtests/qtest/png_filter/06--32-1-8.decoded b/libtests/qtest/predictors/06--32-1-8.decoded
index 58b7060..58b7060 100644
--- a/libtests/qtest/png_filter/06--32-1-8.decoded
+++ b/libtests/qtest/predictors/06--32-1-8.decoded
diff --git a/libtests/qtest/png_filter/07--32-3-8.data b/libtests/qtest/predictors/07--32-3-8.data
index 577ba70..577ba70 100644
--- a/libtests/qtest/png_filter/07--32-3-8.data
+++ b/libtests/qtest/predictors/07--32-3-8.data
diff --git a/libtests/qtest/png_filter/07--32-3-8.decoded b/libtests/qtest/predictors/07--32-3-8.decoded
index 20658f2..20658f2 100644
--- a/libtests/qtest/png_filter/07--32-3-8.decoded
+++ b/libtests/qtest/predictors/07--32-3-8.decoded
diff --git a/libtests/qtest/png_filter/08--32-1-8.data b/libtests/qtest/predictors/08--32-1-8.data
index f5aea4a..f5aea4a 100644
--- a/libtests/qtest/png_filter/08--32-1-8.data
+++ b/libtests/qtest/predictors/08--32-1-8.data
diff --git a/libtests/qtest/png_filter/08--32-1-8.decoded b/libtests/qtest/predictors/08--32-1-8.decoded
index 9f2c62e..9f2c62e 100644
--- a/libtests/qtest/png_filter/08--32-1-8.decoded
+++ b/libtests/qtest/predictors/08--32-1-8.decoded
diff --git a/libtests/qtest/png_filter/09--32-3-8.data b/libtests/qtest/predictors/09--32-3-8.data
index 03cd2bb..03cd2bb 100644
--- a/libtests/qtest/png_filter/09--32-3-8.data
+++ b/libtests/qtest/predictors/09--32-3-8.data
diff --git a/libtests/qtest/png_filter/09--32-3-8.decoded b/libtests/qtest/predictors/09--32-3-8.decoded
index 4059e57..4059e57 100644
--- a/libtests/qtest/png_filter/09--32-3-8.decoded
+++ b/libtests/qtest/predictors/09--32-3-8.decoded
diff --git a/libtests/qtest/png_filter/10--32-1-8.data b/libtests/qtest/predictors/10--32-1-8.data
index ad8c632..ad8c632 100644
--- a/libtests/qtest/png_filter/10--32-1-8.data
+++ b/libtests/qtest/predictors/10--32-1-8.data
diff --git a/libtests/qtest/png_filter/10--32-1-8.decoded b/libtests/qtest/predictors/10--32-1-8.decoded
index a713a0f..a713a0f 100644
--- a/libtests/qtest/png_filter/10--32-1-8.decoded
+++ b/libtests/qtest/predictors/10--32-1-8.decoded
diff --git a/libtests/qtest/png_filter/11--32-3-8.data b/libtests/qtest/predictors/11--32-3-8.data
index 199c13d..199c13d 100644
--- a/libtests/qtest/png_filter/11--32-3-8.data
+++ b/libtests/qtest/predictors/11--32-3-8.data
diff --git a/libtests/qtest/png_filter/11--32-3-8.decoded b/libtests/qtest/predictors/11--32-3-8.decoded
index b86fc1e..b86fc1e 100644
--- a/libtests/qtest/png_filter/11--32-3-8.decoded
+++ b/libtests/qtest/predictors/11--32-3-8.decoded
diff --git a/libtests/qtest/png_filter/12--32-1-4.data b/libtests/qtest/predictors/12--32-1-4.data
index 09e6287..09e6287 100644
--- a/libtests/qtest/png_filter/12--32-1-4.data
+++ b/libtests/qtest/predictors/12--32-1-4.data
diff --git a/libtests/qtest/png_filter/12--32-1-4.decoded b/libtests/qtest/predictors/12--32-1-4.decoded
index 83e116c..83e116c 100644
--- a/libtests/qtest/png_filter/12--32-1-4.decoded
+++ b/libtests/qtest/predictors/12--32-1-4.decoded
diff --git a/libtests/qtest/png_filter/in1 b/libtests/qtest/predictors/in1
index bb830ec..bb830ec 100644
--- a/libtests/qtest/png_filter/in1
+++ b/libtests/qtest/predictors/in1
diff --git a/libtests/qtest/png_filter/in2 b/libtests/qtest/predictors/in2
index 430a074..430a074 100644
--- a/libtests/qtest/png_filter/in2
+++ b/libtests/qtest/predictors/in2
diff --git a/libtests/qtest/png_filter/out1 b/libtests/qtest/predictors/out1
index 5625f33..5625f33 100644
--- a/libtests/qtest/png_filter/out1
+++ b/libtests/qtest/predictors/out1
diff --git a/libtests/qtest/png_filter/out2 b/libtests/qtest/predictors/out2
index dad129d..dad129d 100644
--- a/libtests/qtest/png_filter/out2
+++ b/libtests/qtest/predictors/out2