oi1n0g16 - grayscale mother image with 1 idat-chunk
oi1n2c16 - color mother image with 1 idat-chunk
oi2n0g16 - grayscale image with 2 idat-chunks
oi2n2c16 - color image with 2 idat-chunks
oi4n0g16 - grayscale image with 4 unequal sized idat-chunks
oi4n2c16 - color image with 4 unequal sized idat-chunks
oi9n0g16 - grayscale image with all idat-chunks length one
oi9n2c16 - color image with all idat-chunks length one 