1. A computerized-implemented method of a computing device for measuring widths of measured parts placed on a platform, the computing device electronically connected to one or more charge coupled device (CCD) cameras, the method comprising: (a) controlling each of the CCD cameras to capture a digital image from a measured part that is placed near the CCD cameras, and obtaining the digital image of the measured part from each of the CCD cameras in a predefined order; (b) obtaining a binary expression from the digital image of the measured part; (c) determining whether the measured part is placed in a correct position on the platform according to the binary expression, the determination comprising: determining whether colors of the binary expression accord with a requirement; obtaining the upper boundary and the lower boundary of the measured part by searching edges of the measured part in the binary expression when the colors of the binary expression accord with the requirement; obtaining two points from the upper boundary of the measured part in the binary expression and another two points from the lower boundary of the measured part in the binary expression according to four predefined points, and obtaining a new midline segment according to the obtained four points, wherein the four predefined points are selected by a user in a standard image that is captured by a CCD camera when the measured part is at a right angle to the CCD camera, and the measured part is within a lens field of the CCD camera; determining whether the new midline segment is within a tolerance range of a midline segment of the four predefined points; determining that the measured part is placed in the correct position on the platform when the new midline segment is within the tolerance range of the midline segment of the four predefined points; and determining that the measured part is not placed in the correct position on the platform when the colors of the binary expression do not accord with the requirement, or when the new midline segment is not within the tolerance range of the midline segment of the four predefined points; (d) obtaining three points from an upper boundary of the measured part in the binary expression and another three points from a lower boundary of the measured part in the binary expression when the measured part is placed in the correct position on the platform; and (e) calculating a width of the measured part according to the obtained three points from the upper boundary of the measured part and the obtained three pointed from the lower boundary of the measured part.