In a radiographic histogram, what does the Y-axis represent?

In a radiographic histogram, the Y-axis represents the frequency of specific signal intensity values. This means that the Y-axis indicates how many pixels in the image correspond to each intensity level measured along the X-axis, which represents the range of signal intensities (often relating to the brightness levels of the image).

In digital radiography, analyzing this histogram is crucial for understanding the distribution of exposures across the image. A well-distributed histogram typically suggests that the image has a wide range of densities and appropriate exposure, which is important for accurate diagnosis. The frequency indicated on the Y-axis helps radiologists see areas of overexposure or underexposure based on how many pixels fall into specific intensity categories. This understanding aids in optimizing image processing and ensuring that radiographic images are both diagnostic and of high quality.