1. An image processing method of locating and recognizing barcodes in an image frame, for locating and recognizing a barcode in a sample image frame comprising at least one barcode, and the image processing method comprising: (a) acquiring a sample image frame; (b) defining a plurality of scan tracks on the sample image frame, wherein a horizontal axis is defined on the sample image frame, and the scan tracks are in parallel with each other and in parallel with the horizontal axis; (c) performing following sampling steps sequentially along each of the scan tracks: (c1) acquiring pixels at positions through which the scan track passes on the sample image frame; (c2) calculating a gray level value of each of the pixels on the scan track; (c3) verifying whether a section possibly having the barcode exists on the scan track; (c4) determining whether the sections possibly having the barcode of two neighboring scan tracks are located at an approximate horizontal axis position; and (c5) marking a quadrilateral area defined by the two sections possibly having the barcode as an area possibly having the barcode; and (d) after performing the sampling step on each of the scan tracks, outputting all areas possibly having the barcode.