ISO 7565:1993

Overview - ISO 7565:1993 (Micrographics readers measurement)

ISO 7565:1993 defines standard methods and instruments for measuring the performance characteristics of readers for transparent microforms (readers specified in ISO 6198). The standard covers objective measurement procedures for magnification, resolution, geometric distortion, screen luminance, screen contrast and film‑gate temperature. Annex A explains the importance of luminance measurement and screen diffusion, and Annex B provides a simple field method using a luxmeter.

Key topics and technical requirements

• Magnification

  • Use a transparent magnification test target with graduations (distance between graduations ≤ 0.2 mm).
  • Measure image length on screen with a graduated reference scale (≥ 200 mm, accuracy ±0.5 %) and compute magnification ratio.
  • Use magnifiers (×3 to ×12) or hand magnifiers/tele‑scope as required.

• Resolution

  • Use ISO resolution test charts (ISO No.1 or No.2 microtest charts / ISO 446 / ISO 3334 references) to determine the character/pattern resolved on the screen at rated magnification and best focus.

• Geometric distortion

  • Test film with a 0.25 mm grid (line thickness ≤ 0.025 mm, film thickness ≤ 0.18 mm).
  • Measure curvilinear distortion (barrel/pincushion), keystone (scale differences), and skew (diagonal differences) by tracing/imaging and calculating percentage displacements.

• Screen luminance and contrast

  • Luminance measured from a single eyepoint (nominally 380 mm from screen or equal to screen diagonal for large screens).
  • Use a cosine‑corrected illuminance meter (±10 %) and a luminance meter/spot photometer matched to CIE photopic response (CIE Pub. 17.4) to record center and corner luminance positions (X, A, B, C, D).
  • Annex A discusses observer perception and diffusion evaluation; Annex B gives a field luxmeter method for approximate checks.

• Film‑gate temperature

  • Procedures and apparatus specified for measuring temperature at the film gate to ensure thermal conditions compatible with microform handling and image quality.

Applications - who uses ISO 7565

• Manufacturers of microform readers and projection equipment (design validation, production test).
• Quality assurance and calibration laboratories (routine verification of magnification, resolution, luminance, contrast, distortion).
• Archives, libraries and imaging service providers (acceptance testing, periodic performance checks).
• Standards bodies and test-house personnel developing conformance programs.

Related standards

• ISO 6198 (Readers for transparent microforms - performance characteristics)
• ISO 6196 series (Micrographics vocabulary)
• ISO 446, ISO 3334 (resolution/test charts)
• ISO 5‑1 to 5‑4 (photographic density measurement)
• CIE Publication No. 17.4 (photopic luminosity curve)

Keywords: ISO 7565, micrographics, readers for transparent microforms, measurement of characteristics, magnification measurement, resolution test chart, geometric distortion, screen luminance, screen contrast, luxmeter, film gate temperature.