unsharpness


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unsharpness

A quantitative measure of the loss of edge detail due to geometric properties of the object and imaging system and not to image noise or X-ray scatter. Unsharpness is usually expressed as the width of the band of changing density or brightness arising from a sudden change in the intensity of the radiation incident on the film or fluorescent screen.

Factors contributing to image unsharpness
Geometric unsharpness, movement unsharpness, absorption unsharpness, image receptor unsharpness and parallax unsharpness. It is known from observation that the total unsharpness is not the direct sum of the contributing factors; rather, it is dominated by the unsharpness of the largest individual factor.

unsharpness

lack of detail in an x-ray picture.
References in periodicals archive ?
Two of the most interesting experiments included radiography of a running windup mouse to demonstrate motion unsharpness and imaging a quartz crystal ball with a perpendicular tube, angled tube and angled image receptor to demonstrate shape distortion.
An additional LCD-shutter operating at a constant frequency of 5 kHz was used to remove the unsharpness due to motion.
And there is also an intellectual unsharpness among the core allies: The old NATO plans to enlarge itself.
Increased imaging time also contributed to motion unsharpness on obese women's films.
Despite the best possible effort, patient factors such as obesity, hypoventilation, and motion unsharpness can hinder diagnostic interpretation.
These include motion of the object or imaging system, which can be minimized through compression and short exposure times, and geometric blur or geometric unsharpness, which is related to the size of the focal spot, source-image distance and distance from the object to the detector.
However, because of artifacts or unsharpness caused by respiratory motion, conventional CT scanners still are not fast enough to image the abdomen optimally.