Gray scale shifts in ultrasound displays

Shifts in the displayed shades of gray were found in the initial evaluation of a gray scale ultrasound display. Quantitative measurements of these shifts were performed. These measurements, along with measurements of scan converter output and photographic exposure time, established television (TV) performance as the major cause of shifts. Random variations in photographic exposure time were shown to cause small random shifts. Recommendations are given to minimize the effects of these shifts in clinical sonograms. To minimize shifts, hardware modifications were made on a similar TV. These modifications substantially improved the TV performance.