1. An apparatus for dynamic contrast enhancement, comprising: a histogram calculator for receiving an input image to generate a luma histogram, wherein the input image includes a plurality of pixels; a feature value calculator for generating a feature histogram according to the high frequency components of all the pixels of the input image and a first relation curve; a first combining unit coupled to the histogram calculator and the feature value calculator for combining the luma histogram with the feature histogram to generate a combined histogram according to the sum of feature values of the feature histogram and a second relation curve; a histogram equalizer for receiving the combined histogram and performing contrast adjustment and integral operations to generate a equalized transfer curve; and a remapper for remapping the input image to generate a contrast enhanced image according to a final transfer curve.