How is sampling frequency expressed in digital imaging?

• A. Pixels per inch
• B. Pixels per millimeter
• C. Bits per pixel
• D. Bytes per millimeter

Answer: (B)

Sampling frequency in digital imaging refers to how often the analog signal is sampled to create a digital representation. This concept is crucial in determining the resolution and detail captured in an image.

Pixels per millimeter is a measure of how many individual pixels are packed into a linear dimension of one millimeter. Higher values indicate greater sampling frequency, leading to more detailed images because more samples are taken in a given area. Therefore, the measurement of pixels per millimeter directly relates to the concept of spatial resolution in imaging.

In contrast, other options measure different aspects of imaging. For instance, pixels per inch is another variant of spatial resolution but is not as commonly used in medical imaging practices, which favor metric measurements. Bits per pixel relates to color depth and how many different colors can be represented per pixel, while bytes per millimeter doesn’t have a standard application in the context of sampling frequency in digital imaging. These measurements serve different purposes, making pixels per millimeter the most appropriate answer for expressing sampling frequency.