Patent ID: 8976192
Filing Date: 2015-03-10
Classification: G09G

Abstract:
1. A contrast control device, comprising: a detecting unit, for calculating an average value and detecting a maximum value according to a plurality of pixels of a current image; a judging unit, for generating a gain index and a brightness index according to the average value; a backlight control unit, for generating a backlight control signal according to the brightness index; a gain generating unit, coupled to the detecting unit, for generating a first contrast gain value and a soft-clamping gain value according to the gain index, the average value and the maximum value and for selecting one from the first contrast gain value and the soft-clamping gain value for output as a second contrast gain value according to an input pixel value of the current image; and a contrast gain processing unit, for generating an output pixel value according to the second contrast gain value and the input pixel value; wherein the gain generating unit comprises: a gain mapping unit, for generating the first contrast gain value according to the gain index, wherein the first contrast gain value is greater than 1; and a saturation compensation unit, coupled to the gain mapping unit, for selecting one from the first contrast gain value and the soft-clamping gain value for output as the second contrast gain value according to the input pixel value, wherein the saturation compensation unit sets the soft-clamping gain value to (m×k) when the average value is greater than a first threshold value and the maximum value is greater than a second threshold value, otherwise the saturation compensation unit sets the soft-clamping gain value to k, and wherein 0<m, k<1 and the m and k values depend on at least one of the average value and the maximum value.