Patent ID: 7019756

Claim:
A brightness control apparatus, comprising: a probability density function calculator to calculate a probability density function based on pixel values of respective pixels of an input image signal; a first setter to set a first upper limit value and a first lower limit value with respect to the pixel values over a first predetermined level in the probability density function; a second setter to set a second upper limit value and a second lower limit value for the pixel values over a second predetermined level in the probability density function; a third setter to set an upper limit value and a lower limit value for a range of pixel values not covered by either the first setter or the second setter; and a brightness value controller to calculate a cumulative distribution function for the probability density function controlled by the first upper limit value and the first lower limit value set by the first setter, and to calculate brightness levels corresponding to the input image signal based on the calculated cumulative distribution function, wherein the second setter outputs the probability density function controlled by the set second upper limit value and the second lower limit value to the brightness value controller, and wherein a mapping function calculator converts the cumulative distribution function into a mapping function for the brightness levels using a formula as follows: G ⁡ ( K ) = CDF ′ ⁡ ( K ) × Maximum ⁢ ⁢ Luminance Number ⁢ ⁢ of ⁢ ⁢ total ⁢ ⁢ image ⁢ ⁢ signal ⁢ ⁢ pixels , G(K) denoting a mapping function, and CDF′(K) denoting a compensated cumulative distribution function.