CDIA Image Capture & Processing Techniques 3 — Questions and Answers
Question 1: What is the recommended minimum scanning resolution for documents intended for OCR processing according to industry best practices?
- 72 dpi
- 150 dpi
- 300 dpi (Correct answer)
- 600 dpi
Correct answer: 300 dpi
300 dpi is the widely accepted minimum resolution for reliable OCR results, providing enough pixel density to accurately distinguish character shapes.
Question 2: Which type of scanner uses a rotating drum to hold the original and a fixed optical head for ultra-high-resolution capture?
- Flatbed scanner
- Sheet-fed scanner
- Drum scanner (Correct answer)
- Overhead scanner
Correct answer: Drum scanner
Drum scanners mount the original on a spinning cylinder and use a photomultiplier tube to capture extremely high-resolution images, often used in professional prepress.
Question 3: In document imaging, what does 'bit depth' determine?
- The physical scan speed in pages per minute
- The number of distinct tonal values that can be represented per pixel (Correct answer)
- The compression ratio applied to the output file
- The maximum document size the scanner can accept
Correct answer: The number of distinct tonal values that can be represented per pixel
Bit depth defines how many discrete gray levels or color values each pixel can represent; 1-bit gives black/white only, while 8-bit provides 256 gray levels.
Question 4: What is the purpose of a patch code sheet used in production document scanning?
- Calibrating scanner color accuracy
- Triggering automatic batch or document separation in the scanning workflow (Correct answer)
- Testing scanner optical resolution
- Encoding encryption keys for secure documents
Correct answer: Triggering automatic batch or document separation in the scanning workflow
Patch code sheets contain specific barcode patterns recognized by scanning software to automatically separate document batches or define new document boundaries.
Question 5: Which algorithm is commonly used to remove isolated noise pixels (salt-and-pepper noise) from a binary scanned image?
- Gaussian blur
- Median filter (Correct answer)
- Unsharp mask
- Histogram equalization
Correct answer: Median filter
The median filter replaces each pixel with the median value of its neighborhood, effectively removing isolated noise pixels while preserving edges.
Question 6: When scanning double-sided documents, what feature allows a scanner to capture both sides in a single pass without manually flipping pages?
- Automatic Document Feeder (ADF)
- Duplex scanning (Correct answer)
- Batch separation
- Auto-crop
Correct answer: Duplex scanning
Duplex scanning uses sensors or mirrors on both sides of the document path to simultaneously capture front and back of each page in one pass.
Question 7: What is 'image cleanup' or 'image enhancement' software typically used for in document capture workflows?
- Compressing images after scanning
- Automatically improving image quality by removing defects like speckles, borders, and skew (Correct answer)
- Indexing document content for search
- Converting scanned images to PDF format
Correct answer: Automatically improving image quality by removing defects like speckles, borders, and skew
Image cleanup software applies automated post-processing algorithms to correct scanning artifacts, remove borders, fix orientation, and improve image quality before storage or OCR.
CDIA Image Capture & Processing Techniques 3
What is the recommended minimum scanning resolution for documents intended for OCR processing according to industry best practices?