1. An image generating apparatus for emphasizing an edge based on image characteristics, the image generating apparatus comprising: an edge extractor for extracting an edge region from an input original image; an edge gain calculator for calculating an edge gain indicating a degree for emphasizing the edge region for each of a plurality of image regions of the original image; an edge threshold calculator for calculating an edge threshold indicating a degree of complexity between pixels for each of the plurality of image regions of the original image; and a controller for combining the edge region extracted by the edge extractor with the edge gain calculated by the edge gain calculator, performing thresholding by adjusting the edge threshold calculated by the edge threshold calculator for the edge region combined with the edge gain, and combining the thresholding-applied edge region with the original image to output a final image.