If the lines per frame is increased while the imaging depth remains unchanged, what happens to the frame rate?

If the lines per frame is increased while the imaging depth remains unchanged, what happens to the frame rate?

• A. frame rate decreases
• B. this cannot happen
• C. frame rate increases
• D. number of shades of gray

Answer: (A)

When you increase the number of scan lines collected for each frame while keeping imaging depth the same, the time to acquire a single frame goes up. The time to acquire each line is fixed at the given depth, so adding more lines per frame means you must spend more time per frame. Since frame rate is how many frames you can acquire each second, the more lines you collect per frame, the fewer frames you can produce per second. This makes the frame rate drop. For a quick check, frame rate equals the line rate (lines per second) divided by lines per frame. If the line rate stays constant and you increase lines per frame, the frame rate decreases. For example, with 2000 lines per second and 800 lines per frame, you get 2.5 frames per second. Increasing to 1600 lines per frame gives 1.25 frames per second. The number of shades of gray isn’t affected by how many lines you acquire per frame; that depends on system bit depth and dynamic range, not frame rate.

When you increase the number of scan lines collected for each frame while keeping imaging depth the same, the time to acquire a single frame goes up. The time to acquire each line is fixed at the given depth, so adding more lines per frame means you must spend more time per frame. Since frame rate is how many frames you can acquire each second, the more lines you collect per frame, the fewer frames you can produce per second. This makes the frame rate drop.

For a quick check, frame rate equals the line rate (lines per second) divided by lines per frame. If the line rate stays constant and you increase lines per frame, the frame rate decreases. For example, with 2000 lines per second and 800 lines per frame, you get 2.5 frames per second. Increasing to 1600 lines per frame gives 1.25 frames per second.

The number of shades of gray isn’t affected by how many lines you acquire per frame; that depends on system bit depth and dynamic range, not frame rate.