DIS Image Processing & Enhancement 3 — Questions and Answers
Question 1: Which color adjustment tool in image editing maps specific input tonal values to desired output values using a custom curve?
- Hue/Saturation
- Curves (Correct answer)
- Brightness/Contrast
- Color Balance
Correct answer: Curves
The Curves tool allows precise mapping of input tonal values to output values across the full tonal range, offering fine control over contrast and color.
Question 2: In image processing, morphological dilation of a binary image will:
- Shrink foreground objects by removing boundary pixels
- Expand foreground objects by adding pixels at boundaries (Correct answer)
- Detect and highlight edges of objects
- Fill holes within foreground regions
Correct answer: Expand foreground objects by adding pixels at boundaries
Dilation adds pixels to the boundaries of foreground objects using a structuring element, expanding their size and filling small gaps.
Question 3: What does the 'Threshold' slider in an unsharp mask filter do?
- Sets the blur radius of the reference image
- Defines how different a pixel must be from its surroundings before sharpening is applied (Correct answer)
- Controls the maximum brightness boost allowed
- Determines how many passes of sharpening are applied
Correct answer: Defines how different a pixel must be from its surroundings before sharpening is applied
The threshold value prevents sharpening of pixels whose tonal difference from neighbors is smaller than the specified value, protecting smooth areas like skin from over-sharpening.
Question 4: Which demosaicing algorithm produces the highest quality output from a Bayer pattern RAW file but requires the most processing time?
- Nearest-neighbor interpolation
- Bilinear interpolation
- AHD (Adaptive Homogeneity-Directed) demosaicing (Correct answer)
- Pattern recognition downsampling
Correct answer: AHD (Adaptive Homogeneity-Directed) demosaicing
AHD demosaicing adaptively selects the best interpolation direction for each pixel, producing superior edge detail and color accuracy at the cost of higher computational demand.
Question 5: A 'luminosity mask' in advanced compositing selects pixels based on:
- Their hue and saturation values
- Their brightness values relative to the tonal range (Correct answer)
- Their position within the image frame
- Their proximity to a hand-drawn selection
Correct answer: Their brightness values relative to the tonal range
Luminosity masks create selections weighted by pixel brightness, allowing edits to be applied with natural feathering that respects the tonal values in the image.
Question 6: What is the primary advantage of performing noise reduction before sharpening in a processing workflow?
- Noise reduction requires less processing power when applied first
- Sharpening amplifies noise, so reducing noise first prevents artifacts from being enhanced (Correct answer)
- The order has no meaningful effect on the final result
- Sharpening algorithms require a clean signal to calculate edge masks
Correct answer: Sharpening amplifies noise, so reducing noise first prevents artifacts from being enhanced
Sharpening increases local contrast including noise, so removing noise first ensures only genuine detail edges are enhanced rather than amplifying random artifacts.
Question 7: In Lab color mode, lightness adjustments made to the L channel do NOT affect:
- Overall image brightness
- Shadow and highlight detail
- Color saturation and hue (Correct answer)
- Midtone contrast
Correct answer: Color saturation and hue
In Lab color space, the L channel is completely separate from the a* and b* color channels, so luminosity adjustments leave saturation and hue unaffected.
DIS Image Processing & Enhancement 3
Which color adjustment tool in image editing maps specific input tonal values to desired output values using a custom curve?