浮動小数点数
Floating point numbers can represent linear light levels spacing the samples semi-logarithmically. Floating point representations also allow for drastically larger dynamic ranges as well as negative values. Most systems first supported 32-bit per channel single-precision, which far exceeded the accuracy required for most applications. In 1999, Industrial Light &amp; Magic released the open standard image file format OpenEXR which supported 16-bit-per-channel half-precision floating-point numbers. At values near 1.0, half precision floating point values have only the precision of an 11-bit integer value, leading some graphics professionals to reject half-precision in situations where the extended dynamic range is not needed.