Contrast mapping and evaluation for electronic X-ray images on CRT display monitor

Simple chest X-rays on film are the most common type of image in medical diagnosis. However, amongst the various types of medical X-ray images, they require the highest level of display quality due to the fact that the body structures they capture on film have varying degrees of permeability to X-rays. Conventional high-definition digital display technology has not always been able to match the quality of such film images. This has been a major impediment against progress toward the complete digitization of simple chest X-rays. The intent of this paper is to examine that, when applied to medical diagnosis of chest X-rays, super-high-definition (SHD) images (digital images with resolution exceeding that of HDTV) are capable of producing a level of quality of diagnostic accuracy on a par with conventional film images. The authors start out by seeking out the overall transmission characteristics of a system that uses digital radiography and a film digitizer to digitize images. They then derive gray-scale transform characteristics based on the luminance linear method for approximating, as closely as possible on a CRT, film images on a light box that have wide dynamic range and high luminance. Finally, the authors present the results of image evaluation experiments using high-definition CRT monitors. These results indicate that conventional film images and those on super-high-definition CRT monitors have nearly the same quality. They also show that the contrast mapping selected by radiologists and theoretical luminance linear characteristics were almost the same except in low-luminance regions. The authors also discuss radiologists´ comments on CRT monitors after they participated in the evaluation experiment.