ANSI IES TM-30-20 PDF

Full title and description

ANSI/IES TM-30-20 — Technical Memorandum: IES Method for Evaluating Light Source Color Rendition. A method and reporting format developed by the IES Color Committee (adopted as an American National Standard) for objectively characterizing and communicating the color-rendering properties of electric light sources using a set of numerical metrics and graphics.

Abstract

TM-30-20 defines a reproducible procedure to evaluate how a test light source renders color relative to a reference illuminant of similar correlated color temperature. The method produces a fidelity index (Rf), a gamut index (Rg), per-sample fidelity values, and graphical outputs (notably the Color Vector Graphic) based on a palette of real-world color evaluation samples. The metric suite is intended to give designers, manufacturers, specifiers, and researchers more complete and application-relevant information about color rendition than legacy single-number metrics.

General information

• Status: Originally published/republished as ANSI/IES TM-30-20 (2020); later updated by ANSI/IES TM-30-24 (2024). TM-30-20 remains the widely referenced 2020 technical memorandum edition.
• Publication date: 2020 (republished as ANSI/IES TM-30-20).
• Publisher: Illuminating Engineering Society (IES), New York (ANSI/IES designation).
• ICS / categories: 91.160 — Lighting.
• Edition / version: ANSI/IES TM-30-20 (Technical Memorandum, 2020).
• Number of pages: Approximately 34 pages (core Technical Memorandum as published in 2020; later IES publications and bundles may include extended annex material).

Scope

The standard applies to light sources and lighting systems intended for general illumination (primarily nominally white sources whose chromaticity lies near the Planckian locus) at photopic light levels. It specifies calculation steps, required data (spectral power distribution of the test source and reference illuminant), the set of color evaluation samples (CES), grouping into hue-angle bins, the color-difference formula and color space to be used, and presentation/reporting formats (including recommended report layouts and annex guidance for specification).

Key topics and requirements

• Definition and calculation of the fidelity index (Rf) — average closeness of rendered colors to a reference.
• Definition and calculation of the gamut index (Rg) — measure of mean change in color gamut/chroma produced by the test source.
• Use of a palette of color evaluation samples (99 real-world reflectances) and grouping into 16 hue bins for localized analysis.
• Color Vector Graphic (CVG) to visualize average hue and chroma shifts by hue bin.
• Specified reference illuminant selection (CIE D-series or Planckian reference) based on correlated color temperature (CCT) of the test source.
• Use of a perceptually uniform color space and chromatic adaptation transform (CAM02-UCS-based computations) for color-difference calculations.
• Reporting templates and specification guidance provided in annex material (including recommended criteria and evidence supporting specification thresholds).

Typical use and users

TM-30-20 is used by lighting manufacturers (product development and data sheets), lighting designers and specifiers (selecting sources for visual tasks, retail, hospitality, museums), researchers and standards bodies (comparative studies and method development), test labs and certification bodies, and facility managers interested in objective color-quality data. It is often applied alongside metrics for efficacy and photobiological quantities when specifying or comparing light sources.

Related standards

IES TM-30 earlier editions (TM-30-15, TM-30-18) and later updates (TM-30-24); CIE publications on color rendering and colorimetry (for example, documents that define reference illuminants and color-difference methods); legacy color-rendering metrics such as CIE Ra (CRI) and CQS; and related ANSI/IES documents that address chromaticity and reporting conventions.

Keywords

TM-30, ANSI/IES, color rendering, fidelity index (Rf), gamut index (Rg), color vector graphic, color evaluation samples (CES), CCT, Duv, CAM02-UCS, spectral power distribution, lighting specification.

FAQ

Q: What is this standard?

A: TM-30-20 is an IES technical memorandum (adopted as an American National Standard) that specifies a modern, multi-metric method to evaluate and report how light sources render colors compared to a reference illuminant.

Q: What does it cover?

A: It covers calculation procedures (from spectral data to tristimulus values), the set of color evaluation samples and hue-bin grouping, the fidelity and gamut indices, per-sample and per-bin measures, the Color Vector Graphic, and recommended report and specification guidance (annex material that links TM-30 measures to specification outcomes).

Q: Who typically uses it?

A: Lighting manufacturers, designers and specifiers, testing laboratories, standards developers, researchers, and institutions (e.g., museums, retailers) that need objective, application-relevant information about color rendition.

Q: Is it current or superseded?

A: TM-30-20 is the 2020 technical memorandum edition. The IES published a further update as ANSI/IES TM-30-24 (2024); users should consult the most recent IES publication for current normative text and annex updates. TM-30-20 remains widely cited in literature and practice for historical and reference purposes.

Q: Is it part of a series?

A: Yes. TM-30 originated with TM-30-15 (2015), was revised (TM-30-18 and republished as TM-30-20), and has continued development through later IES technical memoranda. The method suite is maintained by the IES Color Committee and is published alongside related IES/ANSI documents on color and chromaticity.

Q: What are the key keywords?

A: Color rendering, TM-30, Rf, Rg, Color Vector Graphic, CES (color evaluation samples), spectral power distribution, CCT, Duv, CAM02-UCS.