1. A method of generating a manga-style image from an input image, comprising: generating a line drawing from the input image; generating a manga-style screening from the input image; and overlaying the line drawing and the manga-style screening to generate the manga-style image, wherein the input image is a color photograph or a color image, wherein generating the line drawing from the input image comprises detecting edge lines from the input image, calculating an importance value of each of the edge lines, and obtaining structure lines by removing lines with importance values smaller than a threshold, wherein detecting edge lines comprises extracting edge pixels from the input image, connecting the edge pixels into lines using 8-connectivity, breaking the connected lines into pieces at the point with abrupt changes in tangent, and re-connecting broken lines with similar tangent value into a single line.