ISO 19093:2018/Amd 1:2020

Overview

ISO 19093:2018/Amd 1:2020 is an important amendment to the ISO 19093:2018 standard, issued by the International Organization for Standardization (ISO). This document focuses on the measurement of low-light performance in digital cameras, with particular attention to the chroma decrease calculation. The amendment provides updated methods for accurately assessing how digital cameras capture color under low-light conditions, a crucial factor in digital photography quality.

This standard supports manufacturers, testers, and photographers by ensuring consistent, reliable measurement protocols for low-light imaging performance. It refines the techniques for chroma evaluation, based on the CIELAB color space, to compensate for color shifts and degradation in dim illumination.

Key Topics

• Chroma Decrease Calculation:
  The amendment introduces a precise formula to calculate chroma decrease by comparing the color saturation (chroma) of specified color patches under low-light and reference lighting conditions. This method quantifies how color richness diminishes as light decreases.

• White Reference Patch Use:
  A white patch located in the test chart’s lower left corner (designated as D4) is mandated to serve as the white reference for CIELAB calculations. This helps compensate for any color casts that appear in images captured under low-light settings, ensuring more accurate color evaluation.

• Specified Color Patches:
  The standard defines 18 mandatory color patches within the upper-centered part of the test chart for chroma measurement, identified as patches D1–D3, E1–E3, F1–F3, G1–G3, H1–H3, and I1–I3. Optional patches exist but are not required. This targeted selection enhances standardization and repeatability across testing environments.

• Corrections to Test Chart Patch Identification:
  Minor corrections in patch labeling are included, such as replacing patch "C7" with "C8," improving clarity and consistency in test procedures.

Applications

• Digital Camera Manufacturers:
  Use this standard to accurately assess and improve the low-light capabilities of new camera models, ensuring competitive and reliable color reproduction in adverse lighting.

• Camera Testing Laboratories:
  Adopt the amendment procedures to provide standardized, impartial evaluations of camera performance, supporting quality control and certification efforts.

• Photography Industry Professionals:
  Leverage standardized low-light performance data to make informed decisions about camera selection for projects requiring accurate color fidelity in dim environments.

• Research and Development:
  Facilitate advances in image sensor and processing technologies by benchmarking improvements in chroma retention at low-light levels.

Related Standards

• ISO 12232 – Photographic Exposure - Determining Exposure Index, ISO Speed Ratings, and Recommended Exposure Index - relevant for comprehensive camera performance evaluation including sensitivity.

• ISO 15739 – Image quality measurement methods, useful for complementary analysis of noise and resolution under different conditions.

• ISO/IEC 20906 – Test charts for camera image quality evaluation, which provides standardized patterns supporting consistency in image quality assessment.

By adhering to ISO 19093:2018/Amd 1:2020, stakeholders in digital imaging gain access to a refined, industry-recognized method for measuring and reporting the critical aspect of color degradation under low-light, enhancing the overall quality assurance and development of digital cameras.