A histogram in digital radiography refers to the:

• A. Bar graph of the distribution of signal intensities
• B. Range of exposure values that can be detected by the receptor
• C. Size of the digital matrix
• D. Number of brightness levels that can be assigned to a pixel

Answer: (A)

In digital radiography, a histogram shows how pixel values (signal intensities) are distributed across the image. A histogram is a bar graph where the horizontal axis represents gray levels (signal intensities) and the vertical axis indicates how many pixels have each level. This visualization helps you assess exposure and contrast—the spread and position of the histogram reflect whether the image is overexposed, underexposed, or properly exposed. It’s not about the receptor’s detectable exposure range (dynamic range), the size of the digital matrix, or the number of brightness levels per pixel. So, the histogram is best described as the bar graph of the distribution of signal intensities.