When viewing a digital image, pixel bit depth will have a direct influence on which quality factor?

Pixel bit depth refers to the number of bits used to represent the color of a single pixel in a digital image. It directly influences several factors in image quality, but in this case, it primarily affects the scale of contrast.

A higher pixel bit depth allows for a greater range of gray levels, which enhances the scale of contrast in the image. This means that images with greater bit depth can depict more subtle differences in density between adjacent pixels, leading to richer and more detailed images.

While other factors like brightness, mottle, and spatial resolution play important roles in image quality, they are not as directly influenced by pixel bit depth. Brightness is affected by the exposure levels and the calibration of the imaging system, mottle relates to the noise in the image which can be influenced by other factors such as the electronics of the imaging system, and spatial resolution pertains to the ability to distinguish small details in an image but is more related to the detector characteristics and imaging system configuration rather than pixel depth alone. Therefore, the correct response focuses on the scale of contrast, which pixel bit depth significantly enhances.