In July 2011, Park et al [15] presented a method that combines both barcode detection and natural feature tracking methods to track a planar object efficiently on mobile devices. For detecting a region and estimating the initial pose of a QRCode, this method used vertices of position markers. Typically, a QRCode has an alignment-marker that scans inside the data pattern correctly. It is very challenging to detect a small-scale alignment marker from a camera image. Thus, this method detected the QRCode using only position-markers from the acquired camera image. To do this, QRCode can be used to identify position-markers. From a camera image, the method determined several candidate regions which are produced by closed contour detection.