Image Processing & Enhancement Flashcards

Which technique involves blending multiple exposures of the same scene to create a single image with optimal exposure across all tonal zones?

Answer: Exposure fusion / HDR merging

Exposure fusion or HDR merging combines bracketed exposures so that well-exposed pixels from each frame contribute to a single image with extended dynamic range.

The 'Radius' parameter in a sharpening tool controls:

Answer: How far edge halos extend from detected boundaries

Radius defines how many pixels from a detected edge are included in the sharpening halo, with larger values producing wider and more visible edge transitions.

When dodging and burning for portrait retouching, working on a gray-filled layer set to which blend mode allows non-destructive tonal painting?

Answer: Overlay

Overlay mode causes 50% gray to have no effect, while painting lighter grays dodges and darker grays burns, enabling non-destructive dodge-and-burn on a separate layer.

What does posterization in image processing do?

Answer: Reduces the number of tonal levels, creating flat areas with hard transitions

Posterization limits the number of distinct tonal steps in each channel, flattening gradients into solid color bands separated by abrupt tonal jumps.

In image processing, a Sobel operator is primarily used for:

Answer: Detecting edges by calculating image gradients

The Sobel operator convolves the image with kernels that approximate horizontal and vertical derivatives, highlighting areas of rapid intensity change (edges).

Color grading using the 'Lift, Gamma, Gain' model adjusts which three tonal zones respectively?

Answer: Shadows, Midtones, Highlights

Lift controls the shadow (black) point, Gamma shifts the midtone response, and Gain adjusts the highlight (white) point in the Lift/Gamma/Gain color grading model.

Which method best removes lens vignetting without brightening pixels already at maximum value?

Answer: Applying a lens correction profile that applies inverse vignette compensation

A lens correction profile applies mathematically derived inverse vignetting compensation specific to the lens, brightening corners accurately without risk of clipping.