Definition
The Japanese Color Aptitude Test (also: Triangle Test) is a standardised colour aptitude test described in ASTM E1499-16 as a complementary qualification instrument alongside the FM100. The test consists of two modules:
Module 1 — Triangle Test (§6.3.2)
The Triangle Test consists of 20 sets of three colour chips. In each set, two chips are identical and one chip deviates slightly — the colour difference is small (typically ΔE 1–3). The colour assessor identifies the deviating chip.
A low score indicates limited discrimination of small colour differences. The test is specifically designed to measure the ability to detect subtle colour differences in conditions comparable to industrial quality control.
Module 2 — Magnitude Scaling (§6.4.2)
The second module of the Japanese Color Aptitude Test tests the ability to assess the magnitude of colour differences. The colour assessor is shown pairs of colour chips and must indicate how large the difference is on a scale. This measures not only whether someone sees a difference, but also whether the perceptual scale distribution matches the actual ΔE values.
Position within ASTM E1499-16
ASTM E1499-16 describes a three-stage selection process for colour assessors:
- §6.2.1: Pseudoisochromatic plates (Ishihara) — screening for colour vision deficiencies
- §6.2.2 / §6.3.1: FM100 — hue discrimination measurement
- §6.3.2 / §6.4.2: Japanese Color Aptitude Test — threshold discrimination and magnitude scaling
The Japanese Color Aptitude Test is recommended by the standard as a complement to the FM100, particularly for roles where assessing the magnitudeof colour differences is relevant (production acceptance, pass/fail decisions).
Relevance to ColorAptitude™
ColorAptitude™'s chroma threshold assessment is methodologically comparable to the Triangle Test: the user identifies subtle colour differences across hue, lightness and chroma. The magnitude scaling module of ColorAptitude™ implements the methodology of §6.4 directly, with OKLCH stimuli.
Unlike the physical test, ColorAptitude™ uses its own stimuli in the OKLCH colour space and its own norm data — it is not a digital replica of the Japanese Color Aptitude Test.