Comparison of grayscale and color-scale renderings of digital medical images for diagnostic interpretation.

Medical images are increasingly being rendered as digital images that are displayed on a monitor to provide diagnoses. However, these images are often rendered in grayscale. In this context, we compare the detectability of low-contrast signals between digital grayscale images and color-scale images. Low-contrast phantom images were rendered with the use of five color tables (gray, blue, red, yellow, and green). The 32 acquired images sorted in random order were evaluated by nine observers, and their observations were subjected to receiver operating characteristic analysis. In addition, the evaluators' preferred color and their eye fatigue upon image observation were compared. The low-contrast resolutions of yellow and green color scales were superior to that of grayscale. The use of yellow resulted in the least eye fatigue, and importantly our results indicate that the interpretation of digital medical images can be improved when these images are rendered in a "yellow scale" rather than grayscale.