Design consideration for X-ray: trade-offs in noise, contrast and blur affect image quality and performance

We study the effect of simultaneous variation of contrast, noise and blur on the perception of digital X-ray images. Three images are processed with different levels of X-ray photon noise, different luminance (grey level) ranges and different amounts of Gaussian blur. Observers have to rate the quality of the images on a numerical scale. To study how the quality judgement is related to the visibility of small details ('diagnostic' quality), an artificial detail is added to each image. The detail can be in two possible locations. In a two-alternative forcedchoice experiment the visibility of this detail is measured. One of the conclusions is that the quality judgement is based mainly on blur whereas the visibility of details is affected by noise.