Which factor primarily affects the brightness of a digital radiographic image?

The brightness of a digital radiographic image is primarily influenced by window level, which is a part of the image manipulation process in digital radiography. The window level determines the midpoint of the range of grayscale values displayed in the image. By adjusting the window level, you can brighten or darken the entire image, effectively controlling the visibility of the structures within the radiograph. This adjustment allows radiologists to enhance the interpretability of the images based on the specific diagnostic needs.

While exposure time contributes to the overall exposure of the image, and pixel pitch relates to the spatial resolution, these factors do not directly control the brightness of the final displayed image. Film speed pertains to traditional film-based imaging and is not relevant in the context of digital radiographic systems. Thus, window level is crucial for adjusting the brightness perception of digital images, making it the correct choice in understanding how to manipulate brightness effectively in radiographic images.