The purpose of this article is to introduce you a new subpixel image processing method. This method is designed for use in the measuring device for the accurate measurement of dimensions in the building industry. The construction of the optical part of the measuring device and the new method of the image processing are closely connected. This is the reason to introduce measuring device construction too, especially the optical part of the measuring device. The construction of the optical part of the measuring device is discussed in an initial part of the article then the link between the construction of the measurement device and the image processing subpixel analysis method is presented. Realization of an algorithm for the subpixel image processing method is presented too. Some additional information about this measurement system is present in conclusion.