1. A gamma control data mapping circuit for converting input data into grayscale data to display an original image on a display device, the gamma control data mapping circuit comprising: a boundary calculator for separating the input data into high-order bit data and low-order bit data, and outputting a low-order grayscale boundary and a high-order grayscale boundary by using the high-order bit data; and a grayscale data calculator for dividing a grayscale region defined by the low-order grayscale boundary and the high-order grayscale boundary by a unit grayscale number to calculate unit grayscale data of the grayscale region, multiplying the low-order bit data by the unit grayscale data to calculate linear grayscale data, and adding the low-order grayscale boundary to the linear grayscale data to generate the grayscale data.