Gaps in Color Constancy. Poster B 39 at the VSS 2004 Sarasota meeting Adam Reeves Northeastern University, Boston MA Kinjiro Amano, David Foster UMIST, Manchester, UK RKFvss04.ppt. Color Constancy (CC) in brief displays.
Poster B 39 at the VSS 2004 Sarasota meeting
Northeastern University, Boston MA
Kinjiro Amano, David Foster
UMIST, Manchester, UK
In viewing natural scenes, where objects are known, and one is adapted to the prevailing illuminant, CC is fairly good.
When surface colors are re-arranged to form abstract patterns, as in Mondrians, and presented too briefly for light adaptation,
Note: Good CC matches (84%) occur with >10 secs light adaptation (Brainard, JOSA, ‘98)
To study this task effect further, observers RATED the quality of simulated illumination and material changes.
Mondrians were shown with gaps or without gaps:
Pairs of Mondrians subtending 5.5 deg were shown in succession, each for 1 sec, in darkness, on a calibrated monitor.
We simulated 49 different Munsell papers, chosen at random, on each trial.
The ‘local’ illuminant (that on the central patch) was offset at random by one of 9 steps along the daylight locus.
Global Illuminants were either
1600 K (1st) and 6700 K (2nd), or
4000 K (1st Mondrian), 6700 K (2nd).
First (16 or 4K) Second (6.7K)
14 Observers with normal color vision (Ishihara, RG and YB anomoloscopy).
Observers rated the quality of the simulation of the central patch, from 0 to 100%,
either in hue-saturation (as in a ‘direct’ match), or in material (as in a ‘paper’ match).
They were told the simulation might be good or poor -- their job was just to rate how good it seemed.
They also rated the quality of the illuminant shift between the first and second Mondrians.
Some observers distinguished hue-saturation from material changes, but others seemed unable to do so.
To capture this individual difference, observers were split into two equal groups using the standard deviation (SD) of the differences between their hue-saturation and material ratings.
High SD observers (HSD) were better than average in distinguishing hue-saturation from material;
LSD observers were worse than average.
This split is independent of the observers’ color constancy.
Low SD Observers