When insufficient light is produced by the imaging plate phosphor, the image will appear:

When an imaging plate phosphor produces insufficient light, the resulting image has a grainy appearance. This graininess arises because the lack of light fails to adequately expose the imaging sensor, leading to lower image quality. In radiography, high-quality images require sufficient photon interaction with the imaging plate, which in turn produces adequate light signals that contribute to the final image.

A grainy image indicates that there is variability in the pixel intensities, as some areas may receive enough light while others do not, leading to a lack of uniformity. This is particularly important in radiologic practice since a clearer, more detailed image is crucial for accurate diagnosis. Other characteristics such as sharpness, brightness, or blurriness do not directly describe the outcome of insufficient light production in the way graininess does. Therefore, the correct answer highlights the impact of light production deficiencies on image quality in diagnostic imaging.