Overview
ISO 11698-2:2000 - "Micrographics - Methods of measuring image quality produced by aperture card scanners - Part 2: Quality criteria and control" - defines methods for using the test images specified in ISO 11698-1 to check and control the image quality produced by aperture card scanners. It provides procedural guidance for scanning microimages, establishing a quality reference, and assessing critical imaging characteristics for archival, CAD and document-imaging workflows.
Key topics and requirements
- Scope and linkage: Applies specifically to aperture card scanners and relies on the test images defined in ISO 11698-1. Normative references include ISO 3272-1, ISO 5457, ISO 6196 and ISO 12651.
- Establishing a quality reference: Procedures to create and retain reference bit‑mapped images and hard‑copy prints when the system is at optimum performance; record scanner and system settings.
- Measurement methods: Scan test images into an electronic imaging system and evaluate on-screen or from hard copy. Use calibrated electronic viewing systems (pixel coordinate readout) or calibrated printing with printer‑error correction.
- Key tests and criteria:
- Focus - evaluate resolving patterns and background line separation first.
- Image centring and capture size - check offsets and corner scale readings for centring/scaling errors.
- Image scaling - verify pixel dimensions and reduction ratios against ISO sheet sizes.
- Line straightness and orthogonality - measure raster deviation and angular error using vector overlays or protractors.
- Uniformity of line width - measure line-width consistency at multiple points.
- Resolving power and resolvable line width - determine limit of resolution (line pairs/mm).
- Character legibility and subjective assessment - include representative engineering drawings (type 6 test image) to check real‑world behavior.
- User-defined criteria: The standard provides methods - it does not prescribe pass/fail thresholds; users decide acceptance levels appropriate to their application.
Applications and users
ISO 11698-2 is used to:
- Establish and maintain consistent image quality for digitizing aperture card microimages (engineering drawing archives, CAD museums, technical libraries)
- Qualify and service aperture card scanners
- Validate scanning workflows and vendor deliverables in digitization projects
Typical users:
- Document imaging engineers and technicians
- QA managers in digitization projects
- Scanning service providers and micrographics labs
- Records managers and archives responsible for long‑term digital preservation
Related standards
Keywords: ISO 11698-2:2000, aperture card scanners, micrographics, image quality, test images, quality control, resolving power, scaling error, line straightness, image centring.