Abstract

A fairly large concentric region of short-wavelength light (3-5° inner-outer diameter band) surrounding a small concentric 1° test causes a shift toward redness in the color of the test (red/green equilibrium shifts by as much as 20 nm). The effect of the band is not due to stray light or color contrast at the edge of the test (Wesner & Shevell, 1991). To investigate further the adapting effect of remote noncontiguous short-wavelength fields, we measured red/green equilibria of a 1° test, composed of an admixture of 549- and 660-nm light, surrounded by a concentric band of 32-td, 440-nm or 491-nm light. The inner-outer diameters of the bands were varied: 1–2° (contiguous to the test), 2–3°, 3–4°, 4–5°. We also measured the test superimposed on a 5°, 440-nm or 491-nm adapting field. The test was varied from 6 to 1000 td. As expected, the appearance of the test shifted toward redness when superimposed on a uniform short-wavelength adapting field. Replacing the adapting field with a short-wavelength band that was contiguous to the test, however, produced little or no shift in color appearance. A substantial shift toward redness was found with 440-nm bands at least 1° away from the edge of the test. Much smaller effects were measured for the 491-nm bands, which may be attributed to significantly less S-cone stimulation (~4% of that from the 440-nm light). These results indicate that short-wavelength light has a larger effect on color appearance when it is located some distance away from the test.

© 1991 Optical Society of America