1. A method for image visibility restoration, adapted to an image processing apparatus, comprising: receiving an input hazy image comprising a plurality of input pixels; obtaining edge information of each of the input pixels according to a median filtering operation and a dark channel; determining a transmission map according to each of the input pixels and atmospheric light associated with the input hazy image in each color channel; obtaining a refined transmission map according to the edge information of each of the input pixels and the transmission map; adjusting the refined transmission map by performing a gamma correction operation thereon so as to obtain an enhanced transmission map; determining a color difference value corresponding to each of the color channels; recovering scene radiance for each of the input pixels in each of the color channels according to the corresponding color difference value, the corresponding atmospheric light, and the enhanced transmission map so as to produce a de-hazed image; and outputting the de-hazed image.