In an x-ray imaging system, there are three primary sources of blqr. These are the finite size of the x-ray tube focal spot, movement of the object during the exposure, and the inherent blur of the receptor. An analysis of the composite blur and the optimization of system performance can be greatly simplified by the use of a special nomograph. The quantity of blur, with respect to the dimensions of the object, is a function of the object's position between the focal spot and receptor surface. The position of the object is specified in terms of a parameter, s, which forms one scale of the nomograph. Blur values are linear functions of this parameter. Blur from each primary source is graphed as a function of object position by drawing straight lines between points located on the blur and focal-spot scales. A second nomograph is used to combine the blur from the different sources at a specific object location.