Image unsharpness is the blurring in an image of sharp edges in an object. The contact
radiograph of a star test pattern on the left displays negligible unsharpness, while the x-ray
image on the right reveals noticeable blurring. This is Figure 5-9, repeated here for
convenience. (From Hendee, W. R., Chaney, E. L., and Rossi, R.P. 5 Used with permission.)