libmng - THE MNG library (free software by Gerard Juyn)

*Based on the PNGsuite.* These are basic test images in all of the standard PNG b/w, color and paletted formats. The three rows of images must look identical. If they do not, the PNG supporting code in your software is broken. The first row is actually a single image (snapshot) and is the reference point. The second row contains non-interlaced samples and the third row interlaced samples.
PNGBASxx.mng
Some or all of the following images were used: basn6a16 & basi6a16 - 3x16 bits rgb color + 16 bit alpha-channel basn6a08 & basi6a08 - 3x8 bits rgb color + 8 bit alpha-channel basn4a16 & basi4a16 - 16 bit grayscale + 16 bit alpha-channel basn4a08 & basi4a08 - 8 bit grayscale + 8 bit alpha-channel basn3p08 & basi3p08 - 8 bit (256 color) paletted basn3p04 & basi3p04 - 4 bit (16 color) paletted basn3p02 & basi3p02 - 2 bit (4 color) paletted basn3p01 & basi3p01 - 1 bit (2 color) paletted basn2c16 & basi2c16 - 3x16 bits rgb color basn2c08 & basi2c08 - 3x8 bits rgb color basn0g16 & basi0g16 - 16 bit (64k level) grayscale basn0g08 & basi0g08 - 8 bit (256 level) grayscale basn0g04 & basi0g04 - 4 bit (16 level) grayscale basn0g02 & basi0g02 - 2 bit (4 level) grayscale basn0g01 & basi0g01 - black & white