diff --git a/testfiles/pngsuite-LICENSE.txt b/testfiles/pngsuite-LICENSE.txt
new file mode 100644
index 0000000..8d4d1d0
--- /dev/null
+++ b/testfiles/pngsuite-LICENSE.txt
@@ -0,0 +1,9 @@
+PngSuite
+--------
+
+Permission to use, copy, modify and distribute these images for any
+purpose and without fee is hereby granted.
+
+
+(c) Willem van Schaik, 1996, 2011
+
diff --git a/testfiles/pngsuite/basi0g01.png b/testfiles/pngsuite/basi0g01.png
new file mode 100644
index 0000000..556fa72
Binary files /dev/null and b/testfiles/pngsuite/basi0g01.png differ
diff --git a/testfiles/pngsuite/basi0g02.png b/testfiles/pngsuite/basi0g02.png
new file mode 100644
index 0000000..ce09821
Binary files /dev/null and b/testfiles/pngsuite/basi0g02.png differ
diff --git a/testfiles/pngsuite/basi0g04.png b/testfiles/pngsuite/basi0g04.png
new file mode 100644
index 0000000..3853273
Binary files /dev/null and b/testfiles/pngsuite/basi0g04.png differ
diff --git a/testfiles/pngsuite/basi0g08.png b/testfiles/pngsuite/basi0g08.png
new file mode 100644
index 0000000..faed8be
Binary files /dev/null and b/testfiles/pngsuite/basi0g08.png differ
diff --git a/testfiles/pngsuite/basi2c08.png b/testfiles/pngsuite/basi2c08.png
new file mode 100644
index 0000000..2aab44d
Binary files /dev/null and b/testfiles/pngsuite/basi2c08.png differ
diff --git a/testfiles/pngsuite/basi3p01.png b/testfiles/pngsuite/basi3p01.png
new file mode 100644
index 0000000..00a7cea
Binary files /dev/null and b/testfiles/pngsuite/basi3p01.png differ
diff --git a/testfiles/pngsuite/basi3p02.png b/testfiles/pngsuite/basi3p02.png
new file mode 100644
index 0000000..bb16b44
Binary files /dev/null and b/testfiles/pngsuite/basi3p02.png differ
diff --git a/testfiles/pngsuite/basi3p04.png b/testfiles/pngsuite/basi3p04.png
new file mode 100644
index 0000000..b4e888e
Binary files /dev/null and b/testfiles/pngsuite/basi3p04.png differ
diff --git a/testfiles/pngsuite/basi3p08.png b/testfiles/pngsuite/basi3p08.png
new file mode 100644
index 0000000..50a6d1c
Binary files /dev/null and b/testfiles/pngsuite/basi3p08.png differ
diff --git a/testfiles/pngsuite/basi4a08.png b/testfiles/pngsuite/basi4a08.png
new file mode 100644
index 0000000..398132b
Binary files /dev/null and b/testfiles/pngsuite/basi4a08.png differ
diff --git a/testfiles/pngsuite/basi6a08.png b/testfiles/pngsuite/basi6a08.png
new file mode 100644
index 0000000..aecb32e
Binary files /dev/null and b/testfiles/pngsuite/basi6a08.png differ
diff --git a/testfiles/pngsuite/basn0g01.png b/testfiles/pngsuite/basn0g01.png
new file mode 100644
index 0000000..1d72242
Binary files /dev/null and b/testfiles/pngsuite/basn0g01.png differ
diff --git a/testfiles/pngsuite/basn0g02.png b/testfiles/pngsuite/basn0g02.png
new file mode 100644
index 0000000..5083324
Binary files /dev/null and b/testfiles/pngsuite/basn0g02.png differ
diff --git a/testfiles/pngsuite/basn0g04.png b/testfiles/pngsuite/basn0g04.png
new file mode 100644
index 0000000..0bf3687
Binary files /dev/null and b/testfiles/pngsuite/basn0g04.png differ
diff --git a/testfiles/pngsuite/basn0g08.png b/testfiles/pngsuite/basn0g08.png
new file mode 100644
index 0000000..23c8237
Binary files /dev/null and b/testfiles/pngsuite/basn0g08.png differ
diff --git a/testfiles/pngsuite/basn2c08.png b/testfiles/pngsuite/basn2c08.png
new file mode 100644
index 0000000..db5ad15
Binary files /dev/null and b/testfiles/pngsuite/basn2c08.png differ
diff --git a/testfiles/pngsuite/basn3p01.png b/testfiles/pngsuite/basn3p01.png
new file mode 100644
index 0000000..b145c2b
Binary files /dev/null and b/testfiles/pngsuite/basn3p01.png differ
diff --git a/testfiles/pngsuite/basn3p02.png b/testfiles/pngsuite/basn3p02.png
new file mode 100644
index 0000000..8985b3d
Binary files /dev/null and b/testfiles/pngsuite/basn3p02.png differ
diff --git a/testfiles/pngsuite/basn3p04.png b/testfiles/pngsuite/basn3p04.png
new file mode 100644
index 0000000..0fbf9e8
Binary files /dev/null and b/testfiles/pngsuite/basn3p04.png differ
diff --git a/testfiles/pngsuite/basn3p08.png b/testfiles/pngsuite/basn3p08.png
new file mode 100644
index 0000000..0ddad07
Binary files /dev/null and b/testfiles/pngsuite/basn3p08.png differ
diff --git a/testfiles/pngsuite/basn4a08.png b/testfiles/pngsuite/basn4a08.png
new file mode 100644
index 0000000..3e13052
Binary files /dev/null and b/testfiles/pngsuite/basn4a08.png differ
diff --git a/testfiles/pngsuite/basn6a08.png b/testfiles/pngsuite/basn6a08.png
new file mode 100644
index 0000000..e608738
Binary files /dev/null and b/testfiles/pngsuite/basn6a08.png differ
diff --git a/testfiles/pngsuite/exif2c08.png b/testfiles/pngsuite/exif2c08.png
new file mode 100644
index 0000000..56eb734
Binary files /dev/null and b/testfiles/pngsuite/exif2c08.png differ
diff --git a/testfiles/pngsuite/g03n2c08.png b/testfiles/pngsuite/g03n2c08.png
new file mode 100644
index 0000000..a9354db
Binary files /dev/null and b/testfiles/pngsuite/g03n2c08.png differ
diff --git a/testfiles/pngsuite/g03n3p04.png b/testfiles/pngsuite/g03n3p04.png
new file mode 100644
index 0000000..60396c9
Binary files /dev/null and b/testfiles/pngsuite/g03n3p04.png differ
diff --git a/testfiles/pngsuite/g04n2c08.png b/testfiles/pngsuite/g04n2c08.png
new file mode 100644
index 0000000..a652b0c
Binary files /dev/null and b/testfiles/pngsuite/g04n2c08.png differ
diff --git a/testfiles/pngsuite/g04n3p04.png b/testfiles/pngsuite/g04n3p04.png
new file mode 100644
index 0000000..5661cc3
Binary files /dev/null and b/testfiles/pngsuite/g04n3p04.png differ
diff --git a/testfiles/pngsuite/g05n2c08.png b/testfiles/pngsuite/g05n2c08.png
new file mode 100644
index 0000000..932c136
Binary files /dev/null and b/testfiles/pngsuite/g05n2c08.png differ
diff --git a/testfiles/pngsuite/g05n3p04.png b/testfiles/pngsuite/g05n3p04.png
new file mode 100644
index 0000000..9619930
Binary files /dev/null and b/testfiles/pngsuite/g05n3p04.png differ
diff --git a/testfiles/pngsuite/g07n2c08.png b/testfiles/pngsuite/g07n2c08.png
new file mode 100644
index 0000000..5973464
Binary files /dev/null and b/testfiles/pngsuite/g07n2c08.png differ
diff --git a/testfiles/pngsuite/g07n3p04.png b/testfiles/pngsuite/g07n3p04.png
new file mode 100644
index 0000000..c73fb61
Binary files /dev/null and b/testfiles/pngsuite/g07n3p04.png differ
diff --git a/testfiles/pngsuite/g10n2c08.png b/testfiles/pngsuite/g10n2c08.png
new file mode 100644
index 0000000..b303997
Binary files /dev/null and b/testfiles/pngsuite/g10n2c08.png differ
diff --git a/testfiles/pngsuite/g10n3p04.png b/testfiles/pngsuite/g10n3p04.png
new file mode 100644
index 0000000..1b6a6be
Binary files /dev/null and b/testfiles/pngsuite/g10n3p04.png differ
diff --git a/testfiles/pngsuite/g25n2c08.png b/testfiles/pngsuite/g25n2c08.png
new file mode 100644
index 0000000..03f505a
Binary files /dev/null and b/testfiles/pngsuite/g25n2c08.png differ
diff --git a/testfiles/pngsuite/g25n3p04.png b/testfiles/pngsuite/g25n3p04.png
new file mode 100644
index 0000000..4f943c6
Binary files /dev/null and b/testfiles/pngsuite/g25n3p04.png differ
diff --git a/testfiles/pngsuite/s02i3p01.png b/testfiles/pngsuite/s02i3p01.png
new file mode 100644
index 0000000..2defaed
Binary files /dev/null and b/testfiles/pngsuite/s02i3p01.png differ
diff --git a/testfiles/pngsuite/s02n3p01.png b/testfiles/pngsuite/s02n3p01.png
new file mode 100644
index 0000000..2b1b669
Binary files /dev/null and b/testfiles/pngsuite/s02n3p01.png differ
diff --git a/testfiles/pngsuite/s03i3p01.png b/testfiles/pngsuite/s03i3p01.png
new file mode 100644
index 0000000..c23fdc4
Binary files /dev/null and b/testfiles/pngsuite/s03i3p01.png differ
diff --git a/testfiles/pngsuite/s03n3p01.png b/testfiles/pngsuite/s03n3p01.png
new file mode 100644
index 0000000..6d96ee4
Binary files /dev/null and b/testfiles/pngsuite/s03n3p01.png differ
diff --git a/testfiles/pngsuite/s04i3p01.png b/testfiles/pngsuite/s04i3p01.png
new file mode 100644
index 0000000..0e710c2
Binary files /dev/null and b/testfiles/pngsuite/s04i3p01.png differ
diff --git a/testfiles/pngsuite/s04n3p01.png b/testfiles/pngsuite/s04n3p01.png
new file mode 100644
index 0000000..956396c
Binary files /dev/null and b/testfiles/pngsuite/s04n3p01.png differ
diff --git a/testfiles/pngsuite/s05i3p02.png b/testfiles/pngsuite/s05i3p02.png
new file mode 100644
index 0000000..d14cbd3
Binary files /dev/null and b/testfiles/pngsuite/s05i3p02.png differ
diff --git a/testfiles/pngsuite/s05n3p02.png b/testfiles/pngsuite/s05n3p02.png
new file mode 100644
index 0000000..bf940f0
Binary files /dev/null and b/testfiles/pngsuite/s05n3p02.png differ
diff --git a/testfiles/pngsuite/s06i3p02.png b/testfiles/pngsuite/s06i3p02.png
new file mode 100644
index 0000000..456ada3
Binary files /dev/null and b/testfiles/pngsuite/s06i3p02.png differ
diff --git a/testfiles/pngsuite/s06n3p02.png b/testfiles/pngsuite/s06n3p02.png
new file mode 100644
index 0000000..501064d
Binary files /dev/null and b/testfiles/pngsuite/s06n3p02.png differ
diff --git a/testfiles/pngsuite/s07i3p02.png b/testfiles/pngsuite/s07i3p02.png
new file mode 100644
index 0000000..44b66ba
Binary files /dev/null and b/testfiles/pngsuite/s07i3p02.png differ
diff --git a/testfiles/pngsuite/s07n3p02.png b/testfiles/pngsuite/s07n3p02.png
new file mode 100644
index 0000000..6a58259
Binary files /dev/null and b/testfiles/pngsuite/s07n3p02.png differ
diff --git a/testfiles/pngsuite/s08i3p02.png b/testfiles/pngsuite/s08i3p02.png
new file mode 100644
index 0000000..acf74f3
Binary files /dev/null and b/testfiles/pngsuite/s08i3p02.png differ
diff --git a/testfiles/pngsuite/s08n3p02.png b/testfiles/pngsuite/s08n3p02.png
new file mode 100644
index 0000000..b7094e1
Binary files /dev/null and b/testfiles/pngsuite/s08n3p02.png differ
diff --git a/testfiles/pngsuite/s09i3p02.png b/testfiles/pngsuite/s09i3p02.png
new file mode 100644
index 0000000..0bfae8e
Binary files /dev/null and b/testfiles/pngsuite/s09i3p02.png differ
diff --git a/testfiles/pngsuite/s09n3p02.png b/testfiles/pngsuite/s09n3p02.png
new file mode 100644
index 0000000..711ab82
Binary files /dev/null and b/testfiles/pngsuite/s09n3p02.png differ
diff --git a/testfiles/pngsuite/s32i3p04.png b/testfiles/pngsuite/s32i3p04.png
new file mode 100644
index 0000000..0841910
Binary files /dev/null and b/testfiles/pngsuite/s32i3p04.png differ
diff --git a/testfiles/pngsuite/s32n3p04.png b/testfiles/pngsuite/s32n3p04.png
new file mode 100644
index 0000000..fa58e3e
Binary files /dev/null and b/testfiles/pngsuite/s32n3p04.png differ
diff --git a/testfiles/pngsuite/s33i3p04.png b/testfiles/pngsuite/s33i3p04.png
new file mode 100644
index 0000000..ab0dc14
Binary files /dev/null and b/testfiles/pngsuite/s33i3p04.png differ
diff --git a/testfiles/pngsuite/s33n3p04.png b/testfiles/pngsuite/s33n3p04.png
new file mode 100644
index 0000000..764f1a3
Binary files /dev/null and b/testfiles/pngsuite/s33n3p04.png differ
diff --git a/testfiles/pngsuite/s34i3p04.png b/testfiles/pngsuite/s34i3p04.png
new file mode 100644
index 0000000..bd99039
Binary files /dev/null and b/testfiles/pngsuite/s34i3p04.png differ
diff --git a/testfiles/pngsuite/s34n3p04.png b/testfiles/pngsuite/s34n3p04.png
new file mode 100644
index 0000000..9cbc68b
Binary files /dev/null and b/testfiles/pngsuite/s34n3p04.png differ
diff --git a/testfiles/pngsuite/s35i3p04.png b/testfiles/pngsuite/s35i3p04.png
new file mode 100644
index 0000000..e2a5e0a
Binary files /dev/null and b/testfiles/pngsuite/s35i3p04.png differ
diff --git a/testfiles/pngsuite/s35n3p04.png b/testfiles/pngsuite/s35n3p04.png
new file mode 100644
index 0000000..90b892e
Binary files /dev/null and b/testfiles/pngsuite/s35n3p04.png differ
diff --git a/testfiles/pngsuite/s36i3p04.png b/testfiles/pngsuite/s36i3p04.png
new file mode 100644
index 0000000..eb61b6f
Binary files /dev/null and b/testfiles/pngsuite/s36i3p04.png differ
diff --git a/testfiles/pngsuite/s36n3p04.png b/testfiles/pngsuite/s36n3p04.png
new file mode 100644
index 0000000..b38d179
Binary files /dev/null and b/testfiles/pngsuite/s36n3p04.png differ
diff --git a/testfiles/pngsuite/s37i3p04.png b/testfiles/pngsuite/s37i3p04.png
new file mode 100644
index 0000000..6e2b1e9
Binary files /dev/null and b/testfiles/pngsuite/s37i3p04.png differ
diff --git a/testfiles/pngsuite/s37n3p04.png b/testfiles/pngsuite/s37n3p04.png
new file mode 100644
index 0000000..4d3054d
Binary files /dev/null and b/testfiles/pngsuite/s37n3p04.png differ
diff --git a/testfiles/pngsuite/s38i3p04.png b/testfiles/pngsuite/s38i3p04.png
new file mode 100644
index 0000000..a0a8a14
Binary files /dev/null and b/testfiles/pngsuite/s38i3p04.png differ
diff --git a/testfiles/pngsuite/s38n3p04.png b/testfiles/pngsuite/s38n3p04.png
new file mode 100644
index 0000000..1233ed0
Binary files /dev/null and b/testfiles/pngsuite/s38n3p04.png differ
diff --git a/testfiles/pngsuite/s39i3p04.png b/testfiles/pngsuite/s39i3p04.png
new file mode 100644
index 0000000..04fee93
Binary files /dev/null and b/testfiles/pngsuite/s39i3p04.png differ
diff --git a/testfiles/pngsuite/s39n3p04.png b/testfiles/pngsuite/s39n3p04.png
new file mode 100644
index 0000000..c750100
Binary files /dev/null and b/testfiles/pngsuite/s39n3p04.png differ
diff --git a/testfiles/pngsuite/s40i3p04.png b/testfiles/pngsuite/s40i3p04.png
new file mode 100644
index 0000000..68f358b
Binary files /dev/null and b/testfiles/pngsuite/s40i3p04.png differ
diff --git a/testfiles/pngsuite/s40n3p04.png b/testfiles/pngsuite/s40n3p04.png
new file mode 100644
index 0000000..864b6b9
Binary files /dev/null and b/testfiles/pngsuite/s40n3p04.png differ
diff --git a/testfiles/pngsuite/tbbn0g04.png b/testfiles/pngsuite/tbbn0g04.png
new file mode 100644
index 0000000..39a7050
Binary files /dev/null and b/testfiles/pngsuite/tbbn0g04.png differ
diff --git a/testfiles/pngsuite/tbbn3p08.png b/testfiles/pngsuite/tbbn3p08.png
new file mode 100644
index 0000000..0ede357
Binary files /dev/null and b/testfiles/pngsuite/tbbn3p08.png differ
diff --git a/testfiles/pngsuite/tbgn3p08.png b/testfiles/pngsuite/tbgn3p08.png
new file mode 100644
index 0000000..8cf2e6f
Binary files /dev/null and b/testfiles/pngsuite/tbgn3p08.png differ
diff --git a/testfiles/pngsuite/tbrn2c08.png b/testfiles/pngsuite/tbrn2c08.png
new file mode 100644
index 0000000..5cca0d6
Binary files /dev/null and b/testfiles/pngsuite/tbrn2c08.png differ
diff --git a/testfiles/pngsuite/tbwn3p08.png b/testfiles/pngsuite/tbwn3p08.png
new file mode 100644
index 0000000..eacab7a
Binary files /dev/null and b/testfiles/pngsuite/tbwn3p08.png differ
diff --git a/testfiles/pngsuite/tbyn3p08.png b/testfiles/pngsuite/tbyn3p08.png
new file mode 100644
index 0000000..656db09
Binary files /dev/null and b/testfiles/pngsuite/tbyn3p08.png differ
diff --git a/testfiles/pngsuite/tm3n3p02.png b/testfiles/pngsuite/tm3n3p02.png
new file mode 100644
index 0000000..fb3ef1d
Binary files /dev/null and b/testfiles/pngsuite/tm3n3p02.png differ
diff --git a/testfiles/pngsuite/tp0n0g08.png b/testfiles/pngsuite/tp0n0g08.png
new file mode 100644
index 0000000..333465f
Binary files /dev/null and b/testfiles/pngsuite/tp0n0g08.png differ
diff --git a/testfiles/pngsuite/tp0n2c08.png b/testfiles/pngsuite/tp0n2c08.png
new file mode 100644
index 0000000..fc6e42c
Binary files /dev/null and b/testfiles/pngsuite/tp0n2c08.png differ
diff --git a/testfiles/pngsuite/tp0n3p08.png b/testfiles/pngsuite/tp0n3p08.png
new file mode 100644
index 0000000..69a69e5
Binary files /dev/null and b/testfiles/pngsuite/tp0n3p08.png differ
diff --git a/testfiles/pngsuite/tp1n3p08.png b/testfiles/pngsuite/tp1n3p08.png
new file mode 100644
index 0000000..a6c9f35
Binary files /dev/null and b/testfiles/pngsuite/tp1n3p08.png differ