Check libpng directly into third_party/

third_party/libpng/contrib/pngsuite/README

+
+pngsuite
+--------
+Copyright (c) Willem van Schaik, 1999, 2011, 2012
+Two images (ftbbn0g01.png and ftbbn0g02.png) are by Glenn Randers-Pehrson, 2012
+
+Permission to use, copy, modify, and distribute these images for any
+purpose and without fee is hereby granted.
+
+The 15 "bas*.png" images are part of the much larger PngSuite test-set of
+images, available for developers of PNG supporting software. The
+complete set, available at http:/www.schaik.com/pngsuite/, contains
+a variety of images to test interlacing, gamma settings, ancillary
+chunks, etc.
+
+The "ft*.png" images are "free/libre" replacements for the transparent
+corresponding t*.png images in the PngSuite.
+
+The images in this directory represent the basic PNG color-types:
+grayscale (1-16 bit deep), full color (8 or 16 bit), paletted
+(1-8 bit) and grayscale or color images with alpha channel. You
+can use them to test the proper functioning of PNG software.
+
+    filename       depth type
+    ------------ ------ --------------
+    basn0g01.png   1-bit grayscale
+    basn0g02.png   2-bit grayscale
+    basn0g04.png   4-bit grayscale
+    basn0g08.png   8-bit grayscale
+    basn0g16.png  16-bit grayscale
+    basn2c08.png   8-bit truecolor
+    basn2c16.png  16-bit truecolor
+    basn3p01.png   1-bit paletted
+    basn3p02.png   2-bit paletted
+    basn3p04.png   4-bit paletted
+    basn3p08.png   8-bit paletted
+    basn4a08.png   8-bit gray with alpha
+    basn4a16.png  16-bit gray with alpha
+    basn6a08.png   8-bit RGBA
+    basn6a16.png  16-bit RGBA
+
+    ftbbn0g01.png  1-bit grayscale, black bKGD
+    ftbbn0g02.png  2-bit grayscale, black bKGD
+    ftbbn0g04.png  4-bit grayscale, black bKGD
+    ftbbn2c16.png 16-bit truecolor, black bKGD
+    ftbbn3p08.png  8-bit paletted, black bKGD
+    ftbgn2c16.png 16-bit truecolor, gray bKGD
+    ftbgn3p08.png  8-bit paletted, gray bKGD
+    ftbrn2c08.png  8-bit truecolor, red bKGD
+    ftbwn0g16.png 16-bit gray, white bKGD
+    ftbwn3p08.png  8-bit paletted, white bKGD
+    ftbyn3p08.png  8-bit paletted, yellow bKGD
+    ftp0n0g08.png  8-bit grayscale, opaque
+    ftp0n2c08.png  8-bit truecolor, opaque
+    ftp0n3p08.png  8-bit paletted, opaque
+    ftp1n3p08.png  8-bit paletted, no bKGD
+
+Here is the correct result of typing "pngtest -m bas*.png" in
+this directory:
+
+Testing basn0g01.png: PASS (524 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g02.png: PASS (448 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g04.png: PASS (520 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g08.png: PASS (3 zero samples)
+ Filter 1 was used 9 times
+ Filter 4 was used 23 times
+Testing basn0g16.png: PASS (1 zero samples)
+ Filter 1 was used 1 times
+ Filter 2 was used 31 times
+Testing basn2c08.png: PASS (6 zero samples)
+ Filter 1 was used 5 times
+ Filter 4 was used 27 times
+Testing basn2c16.png: PASS (592 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn3p01.png: PASS (512 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p02.png: PASS (448 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p04.png: PASS (544 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p08.png: PASS (4 zero samples)
+ Filter 0 was used 32 times
+Testing basn4a08.png: PASS (32 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn4a16.png: PASS (64 zero samples)
+ Filter 0 was used 1 times
+ Filter 1 was used 2 times
+ Filter 2 was used 1 times
+ Filter 4 was used 28 times
+Testing basn6a08.png: PASS (160 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn6a16.png: PASS (1072 zero samples)
+ Filter 1 was used 4 times
+ Filter 4 was used 28 times
+libpng passes test
+
+Willem van Schaik
+<willem@schaik.com>
+October 1999