[A study of the perception of radiographic density with magnitude estimation: density perception of high-density areas].

To investigate proper radiographic contrast and latitude based on density perception of the high-density areas of X-ray films, we studied the human characteristics of darkness perception for those areas. Magnitude estimation was used to provide a numerical estimate of the sensory magnitudes for contrast. Experimental figures that imitated the head were imaged on X-ray films. Magnitude estimation of darkness in the surrounding fields showed greater misperception or darker perception. When the density of the background field was high, the larger the density difference between the background and surrounding field, the darker the surrounding field was perceived. This implies that the lighter field is assimilated into the darker field. Since assimilation reduces the perceived density difference between soft tissue and the area around it, using high contrast film is less effective for attempting to increase the physical density difference between such areas. We concluded that psychological assimilation of darkness on contrast perception had a detrimental influence on the density perception of high-density areas on head radiographs.