ISO 15529:2010

Overview

ISO 15529:2010 - "Optics and photonics - Optical transfer function - Principles of measurement of modulation transfer function (MTF) of sampled imaging systems" - defines the principles, terminology and measurement techniques for describing the spatial-frequency performance of sampled imaging systems. The standard is focused on electronic imaging devices and detector arrays (e.g., digital still and video cameras, line-scan imagers, fibre optic bundles). It specifies principal MTFs associated with sampled systems, defines quantitative measures of aliasing, and outlines suitable measurement approaches so results are unique and independent of test equipment.

Key topics and technical requirements

• Definitions and symbols: formal definitions for sampled imaging system, sampling period, Nyquist limit (1/(2a)), line spread function (LSF), optical transfer function (OTF), modulation transfer function (MTF), reconstruction function, aliasing function and aliasing ratio.
• MTF concepts for sampled systems: how the MTF of a sampled imaging system is composed (aperture MTF × reconstruction-function MTF × any upstream/downstream device MTFs), and why the measured MTF can depend on slit position relative to the sampling array.
• Measurement principles: recommended techniques for measuring MTFs associated with sampling apertures, imaging pick-up subsystems and complete systems; use of slit (LSF) or edge (edge spread function) methods as valid starting points where consistent with ISO 9334/9335.
• Aliasing metrics: formal definitions of the aliasing function, aliasing ratio and aliasing potential; methods to measure aliasing so that the degree to which frequencies above Nyquist produce spurious low-frequency content can be quantified.
• Theoretical relationships: Fourier-based relationships linking slit/LSF measurements to the OTF/MTF of sampled systems and treatment of how sampling imposes periodicity and phase dependence.

Practical applications and who uses it

• Camera and sensor designers use ISO 15529 to quantify detector-array resolution, design anti-aliasing filters and select reconstruction algorithms.
• Optical and imaging test laboratories apply the standard to produce repeatable, comparable MTF and aliasing measurements for product qualification and specification.
• Quality assurance and R&D teams in digital imaging, machine vision, medical imaging and remote sensing use the definitions and measurement guidance to assess system performance and troubleshoot sampling artefacts (e.g., moiré).
• Standards bodies and procurement references MTF/aliasing metrics for interoperability, acceptance testing and objective performance claims.

Related standards

• ISO 9334 - OTF definitions and mathematical relationships
• ISO 9335 - OTF measurement principles and procedures
• ISO 11421 - Accuracy of OTF measurement

ISO 15529 is essential for anyone needing standardized, objective evaluation of spatial-frequency response and aliasing behavior in sampled imaging systems. Keywords: ISO 15529, MTF, modulation transfer function, sampled imaging systems, aliasing, Nyquist, detector arrays, OTF, line spread function.