CDIA Image Processing 3 — Questions and Answers
Question 1: In CDIA contexts, what is the primary advantage of MRC (Mixed Raster Content) compression?
- It converts all images to grayscale for uniform processing
- It separately compresses foreground text and background layers for optimal quality and size (Correct answer)
- It applies JPEG compression uniformly across the entire page
- It eliminates the need for OCR processing
Correct answer: It separately compresses foreground text and background layers for optimal quality and size
MRC separates a page into foreground (text/line art) and background (photos/graphics) layers, applying optimal compression to each for better quality at smaller file sizes.
Question 2: Which metric is used to measure the similarity between an original and compressed document image?
- DPI (dots per inch)
- PSNR (Peak Signal-to-Noise Ratio) (Correct answer)
- OCR accuracy rate
- Bit depth
Correct answer: PSNR (Peak Signal-to-Noise Ratio)
PSNR measures the ratio between the maximum possible signal power and noise introduced by compression, indicating image fidelity after compression.
Question 3: What is 'border removal' as applied in document image processing?
- Cropping the image to remove dark edges caused by scanner platens or document holders (Correct answer)
- Removing text from the margins of a scanned document
- Eliminating the document's border graphics
- Deleting page numbers from scanned documents
Correct answer: Cropping the image to remove dark edges caused by scanner platens or document holders
Border removal eliminates dark or irregular edges that appear at scan boundaries due to the scanner platen or document holder being visible.
Question 4: Which filter is most effective for smoothing document images while preserving sharp edges such as text boundaries?
- Gaussian blur
- Median filter
- Box blur
- Bilateral filter (Correct answer)
Correct answer: Bilateral filter
A bilateral filter smooths flat regions while preserving edges by weighting neighboring pixels based on both spatial distance and intensity difference.
Question 5: In document imaging, what does 'auto-crop' functionality accomplish?
- Automatically adjusts image brightness
- Detects and trims the document boundary, removing surrounding scanner background (Correct answer)
- Converts multi-page documents into single pages
- Automatically classifies document types
Correct answer: Detects and trims the document boundary, removing surrounding scanner background
Auto-crop detects the edges of the actual document within the scan area and removes the surrounding scanner background or platen.
Question 6: What is the effect of applying a morphological 'dilation' operation to a binary document image?
- Shrinks white regions and expands black regions
- Expands white regions and can connect nearby broken text strokes (Correct answer)
- Removes isolated noise pixels
- Straightens curved text lines
Correct answer: Expands white regions and can connect nearby broken text strokes
Dilation expands bright (white) regions in a binary image, which can help connect broken character strokes in text recognition preprocessing.
Question 7: Which standard defines the JBIG2 compression algorithm used for bitonal document images?
- ISO 19005
- ITU-T T.88 (Correct answer)
- ISO 32000
- ANSI/AIIM MS44
Correct answer: ITU-T T.88
JBIG2 is defined by ITU-T T.88 and offers high compression ratios for bitonal (black-and-white) document images by using symbol matching.
CDIA Image Processing 3
In CDIA contexts, what is the primary advantage of MRC (Mixed Raster Content) compression?