1. A processing method of a barcode, for detecting a barcode from an original image, the processing method comprising: an edge processing procedure, for converting the original image into a binarized input image; a barcode positioning process, for deriving position information of the barcode, comprising: deriving a plurality of luminance groups according to luminance values of all pixels of the input image; utilizing a determining circuit to determine whether each luminance group complies with an identification bar of the barcode and to derive position information of identification bars; and deriving the position information of the barcode according to the position information of the identification bars; and a projection modification process, for converting the original image into a modified image according to the position information of the barcode.