The graphic overlay on this phantom image represents a grayscale assignment curve. What type of curve is being used?

The graphic overlay on this phantom image represents a grayscale assignment curve. What type of curve is being used?

• A. S-curve
• B. Root curve
• C. Linear curve
• D. Light curve

Answer: (C)

Grayscale assignment curves describe how input pixel values are turned into display brightness. A linear curve means the mapping is direct: equal steps in input produce equal steps in output, so density on the image is represented proportionally across the tonal range. The phantom overlay shows a straight line from dark to light, indicating this 1:1 relationship. That straight-line shape is what a linear curve looks like, so it preserves proportional densities without boosting or compressing contrast. If the curve were non-linear—like an S-shaped curve to enhance midtones or a curved root curve to pull down shadows or highlights—the overlay would appear curved rather than straight. Since the overlay is a straight line, the curve is linear.

Grayscale assignment curves describe how input pixel values are turned into display brightness. A linear curve means the mapping is direct: equal steps in input produce equal steps in output, so density on the image is represented proportionally across the tonal range. The phantom overlay shows a straight line from dark to light, indicating this 1:1 relationship. That straight-line shape is what a linear curve looks like, so it preserves proportional densities without boosting or compressing contrast. If the curve were non-linear—like an S-shaped curve to enhance midtones or a curved root curve to pull down shadows or highlights—the overlay would appear curved rather than straight. Since the overlay is a straight line, the curve is linear.