Measuring surface achromatic color: Toward a common measure for increments and decrements

Abstract

Surface color is traditionally measured by matching methods. However, in some conditions, the color of certain surfaces cannot be measured: The surface simply looks brighter or darker than all the patches on a matching scale. We studied the reliability, validity, and range of application of three different types of simulated Munsell scales (white-, black-, and split-surrounded) as methods for measuring surface colors in simple disk-ring displays. All the scales were equally reliable for matching both increments and decrements, but about 20% of the increments were unmatchable on the white-surrounded scale, about 13% of the decrements were unmatchable on the black-surrounded scale, and about 9% of the increments were unmatchable on the split-surrounded scale. However, matches on all the scales were linearly related. Therefore, it is possible to convert them to common units, using regression parameters. These units provide an extended metric for measuring all increments and decrements in the stimulus space, effectively removing ceiling and floor effects, and providing measures even for surfaces that were perceived as out of range on some of the scales.

Measuring the meter: on the constancy of lightness scales seen against different backgrounds

“…White backgrounds and white-black checkered backgrounds are commonly used in matching experiments, whereas black backgrounds are not so common (Jandó et al, 2003;Agostini & Galmonte, 2002). Nevertheless, there is no deeply rooted theoretical reason why the latter should not be equally employed.…”

“…No significant differences were reported for matches between conditions. The study by Jandó, Agostini, Galmonte, and Bruno (2003) dealt instead with the "unmatchable problem," i.e., the impossibility to match a test stimulus that is an increment to its background to a standard stimulus that is a decrement to its background, and vice versa. While the issue is problematic to both the matching paradigm and the adjustment matching methods (Bruno, 1992;Bruno, Bernardis, & Schirillo, 1997;Whittle & Challands, 1969), Jandó et al confronted the problem only with Munsell scales simulated on a CRT.…”

“…When required to "pick a match," participants in an experiment do not find the task unusual or difficult to understand, even when the matching task itself is revealed to be an impossible one (Jandó, Agostini, Galmonte, & Bruno, 2003). (2) Reflectance scales are now practically ready-made:…”

The functional subdivision of the visual brain: Is there a real illusion effect on action? A multi-lab replication study

“…Nevertheless, it also has its drawbacks: (a) because physical size and illusion are confounded it is difficult to quantify the illusion display effect if there is some effect on grasping that needs to be compared quantitatively to the perceptual effect, and (b) matching two targets in figure-surround configurations to be perceptually equal is in principle very difficult to do, especially when the surrounds have opposite effects (incremental vs. decremental). For an example from lightness perception, see Jandó, Agostini, Galmonte and Bruno (2003). In practice, this presents even more of a problem since the physical size of stimuli will always increase in steps, rather than continuously (e.g., Aglioti et al 1995 used step-sizes of 1 mm, which may be too coarse for a good perceptual match).…”

A selective deficit in the appreciation and recognition of brightness: Brightness agnosia?

“…In this paper, we use the term brightness for 'perceived luminance' and the term lightness for 'perceived reflectance'(Jando et al, 2003).c o r t e x 4 5 ( 2 0 0 9 ) 8 1 6 -8 2 4…”