1. A method for improving printing quality using a printer wherein the method comprises: an application device transmitting an original image comprising a plurality of printing pixels to a driving device; the driving device setting the plurality of printing pixels as a plurality of first printing dots; the driving device detecting an edge of the original image; the driving device setting a plurality of second printing dots according to a plurality of neighboring pixels corresponding to the edge; and the driving device generating an image to be printed according to the plurality of first printing dots and the plurality of second printing dots; wherein the driving device detecting the edge of the original image comprises: the driving device setting a printing pixel in each row of the original image as the edge of the original image when determining the original image is a grayscale image, and a grayscale value of a pixel next to the printing pixel being equal to 0; the driving device setting a printing pixel in each column of the original image as the edge of the original image when determining the original image is a grayscale image, and a grayscale value of a pixel next to the printing pixel being equal to 0; and determining the plurality of printing pixels forms a line via a line drawing API (Application Programming Interface) called by the application device.