What term describes the number of picture elements per inch?

• A. Pixel
• B. Pixel Density
• C. Pixel Interpolation
• D. Pulse Inversion

Answer: (B)

Pixel density is the measure of how many picture elements fit into one inch of the display. It’s expressed as pixels per inch (PPI), and higher density means more detail can be shown in the same physical space, making structures appear sharper and edges crisper. A single picture element is simply a pixel—the basic building block of a digital image. Pixel density differs from pixel interpolation, which is a method used to estimate or create new pixels when resizing images and doesn’t describe how many pixels exist per inch. Pulse inversion, on the other hand, is a Doppler technique used in ultrasound to separate moving from stationary tissue echoes and has no relation to display resolution or pixel count.