1. An image enhancement apparatus, comprising: a global tone mapping curve generator generating a global tone mapping curve for an input image according to global characteristic(s) of the input image; a local tone mapping curve generator generating a local tone mapping curve for each image partition within the input image according to the global tone mapping curve and further a feature of the image partition; a reference gamma voltage generator generating a plurality of reference gamma voltages for each image partition according to the corresponding local tone mapping curve for the image partition; and an image generator generating an output image according to the reference gamma voltages of the image partitions and the input image.