van Tright on von Kries: Two counterexamples

✍ Scribed by Michael H. Brill

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 61 KB
• Volume: 25
• Category: Article
• ISSN: 0361-2317
• DOI: 10.1002/(sici)1520-6378(200002)25:1<75::aid-col12>3.0.co;2-s

✦ Synopsis

Exploring conditions under which von Kries ratios are illuminant-invariant, C. van Trigt produces an error expression, whose first term he claims must be small, as when the visual sensitivities approximate delta functions in wavelength. However, by restricting illuminant and reflectance spectra in several alternative ways, earlier investigators revealed large sets of spectra that render von Kries ratios illuminant-invariant, even though they generate large van-Trigt error terms. van Trigt's proof excludes these spectra based on the unwarranted requirement that separate terms be small in his error expression.