Overview
ISO 17321-1:2012 - Graphic technology and photography: Colour characterisation of digital still cameras (DSCs) - Part 1: Stimuli, metrology and test procedures defines standardized stimuli, metrology and laboratory/field test procedures for characterizing the colour response of digital still cameras intended for photography and graphic technology. The standard focuses on raw (sensor-referred) DSC data and provides two alternative measurement methods: a spectral (Method A) approach using narrow-band illumination and a target-based (Method B) approach using a spectrally and colorimetrically calibrated target. ISO 17321-1 does not specify how to derive scene‑to‑display transformations from raw data.
Key technical topics and requirements
- Two characterization methods
- Method A (spectral sensitivity-based): uses a light source and monochromator to illuminate a diffuse surface at selected wavelengths; requires tightly controlled spectral sampling and radiometric measurements.
- Method B (target-based): uses a calibrated colour target under defined illumination; suitable for studio/field use when target spectra approximate scene spectra.
- Metrology and equipment
- Radiance/irradiance meter accuracy traceable to national standards (example requirement: spectral sensitivity calibration accurate to within 0.1%).
- Monochromator bandpass ≤ 5 nm; sampling interval ≤ bandpass; approximately triangular bandpass shape; integrated radiance outside ±10 nm must be very low (≤ 1/1 000, preferably ≤ 1/10 000).
- Recommended integrating sphere setup for even illumination and ports for camera and meter.
- Camera and capture controls
- Use fixed exposures yielding peak outputs at ~50–90% of saturation.
- Disable automatic gain, adaptive tone reproduction and flash; minimize compression; fix white balance; record all settings.
- Raw data definition and permitted operations
- Raw DSC image data may include A/D conversion plus optional linearization, dark‑current/frame subtraction, shading/sensitivity correction, flare removal, white balancing (so adopted white is achromatic), and missing‑pixel reconstruction - but not output‑referred rendering.
- Informative annexes cover laboratory setup, DSC metamerism index (DSC/SMI), target considerations and converting spectral characterization to scene responses.
Practical applications
- Camera manufacturers - validate and quantify sensor spectral sensitivities and colorimetric performance during development.
- Color scientists and test labs - produce traceable measurements for device profiling and inter-device comparisons.
- Graphic arts and professional photographers - ensure accurate colour capture workflows for reproduction and color management.
- Target and imaging equipment suppliers - design and certify calibration targets and measurement systems.
Related standards (referenced)
Keywords: ISO 17321-1:2012, colour characterisation, digital still cameras, spectral method, target method, metrology, raw image data, camera profiling, monochromator, integrating sphere, DSC metamerism.
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