LN2               755 contrib/libtests/tarith.c    return (png_uint_32)floor(.5 + exp(x * -LN2) * 0xffffffffU);
LN2               760 contrib/libtests/tarith.c    return (png_byte)floor(.5 + exp(log * -LN2) * 255);
LN2               765 contrib/libtests/tarith.c    return (png_uint_16)floor(.5 + exp(log * -LN2) * 65535);