CDIA Image Processing 2 — Questions and Answers
Question 1: Which color space is most commonly used in document imaging for representing grayscale documents?
- RGB
- CMYK
- 8-bit grayscale (Correct answer)
- YCbCr
Correct answer: 8-bit grayscale
8-bit grayscale provides 256 shades of gray and is the standard representation for monochrome document imaging.
Question 2: What does the term 'despeckle' refer to in document image processing?
- Increasing image contrast
- Removing isolated noise pixels (Correct answer)
- Enhancing edge sharpness
- Adjusting image brightness
Correct answer: Removing isolated noise pixels
Despeckle filtering removes isolated noise pixels (salt-and-pepper noise) that appear as random black or white dots on scanned documents.
Question 3: Which image format uses lossless compression and supports transparency, making it suitable for logos in document workflows?
- JPEG
- PNG (Correct answer)
- BMP
- GIF
Correct answer: PNG
PNG uses lossless compression and supports alpha channel transparency, making it ideal for logos and graphics in document workflows.
Question 4: In document scanning, what is 'halftone detection' used for?
- Identifying printed photographs or screened images for appropriate compression (Correct answer)
- Detecting color in black-and-white documents
- Measuring document brightness levels
- Finding watermarks in scanned pages
Correct answer: Identifying printed photographs or screened images for appropriate compression
Halftone detection identifies regions containing photographic or screened content so that appropriate compression (e.g., JPEG) is applied instead of bitonal compression.
Question 5: What is the primary purpose of adaptive thresholding in document binarization?
- Applying a single global threshold to all pixels
- Adjusting the threshold locally based on surrounding pixel values (Correct answer)
- Converting color images to RGB
- Increasing image resolution
Correct answer: Adjusting the threshold locally based on surrounding pixel values
Adaptive thresholding calculates a local threshold for each pixel region, handling uneven illumination and background variation better than a single global threshold.
Question 6: Which scanning artifact occurs when light bleeds through from the reverse side of a thin document page?
- Moiré pattern
- Show-through (bleed-through) (Correct answer)
- Skew
- Salt-and-pepper noise
Correct answer: Show-through (bleed-through)
Show-through or bleed-through occurs when text or images on the reverse side of thin paper are faintly visible on the scanned side.
Question 7: What does a histogram equalization operation do to a document image?
- Redistributes pixel intensity values to improve contrast (Correct answer)
- Compresses the image to reduce file size
- Converts the image to binary black and white
- Rotates the image to correct skew
Correct answer: Redistributes pixel intensity values to improve contrast
Histogram equalization redistributes the intensity values across the full range to enhance overall contrast and detail visibility.
CDIA Image Processing 2
Which color space is most commonly used in document imaging for representing grayscale documents?