Which two controls affect the spatial resolution of the color image?

• A. Line density and ensemble length
• B. Ensemble length and priority
• C. Frequency and line density
• D. Frequency and ensemble length

Answer: (C)

Spatial resolution is about how finely the image samples detail in space. Two controls directly affect that sampling: frequency and line density. Higher transmit frequency shortens the wavelength, which improves the system’s ability to distinguish small structures, boosting both axial and lateral resolution and making color features crisper. Increasing line density means more scan lines cover the same width, so spatial sampling is finer and small color details are resolved more clearly. Ensemble length influences temporal sampling and Doppler sensitivity, affecting frame rate rather than the true spatial sharpness of the color image. So the factors that determine spatial resolution are frequency and line density.