Exponential brightness data is a kind of special data used to match the experience of the human eye. Since human eyes are similar to a logarithm translator, if the raw data of brightness is referenced in exponential mode, then it would be expressed with linear mode by human eyes. Furthermore, exponential data has a higher resolution than linear data in low dimming levels, so in an actual case, to decrease the software design difficulty of brightness adjustment, the designer prefers to map exponential data to linear dimming unit. In practice, a designer may face this obstacle: How to map exponential data to a linear system to get more accurate dimming?