On the most representative colors of the national flag of Spain

Abstract

We report the results of a visual experiment where 53 adult observers with normal color vision, born and living regularly in Spain, were asked to obtain the colors of the flag of Spain they considered most representative. Observers used a laptop screen and software developed by us with six sliders that allowed independent changes of lightness, chroma, and hue for the red and yellow stripes of the Spanish flag. We found no statistically significant differences between the colors reported by civil/military (p=0.150) or male/female (p=0.432) observers. Each observer performed two trials, on consecutive days, with average intra-observer variability being 14 and 17 CIELAB units for red and yellow, respectively. Inter-observer variability, or mean color difference with respect to the mean, was 13 and 17 CIELAB units for the red and yellow, respectively. Chroma differences were the main components in intra- and inter-observer variability. CIELAB ellipsoids were reported, including 95% of the red and yellow stimuli selected by observers. In addition to individual colors, observers in our experiment also paid attention to red-yellow contrast. Color differences between legal values and average visual values in our experiment were 24 and 20 CIELAB units for red and yellow, respectively. The methodology described in this paper may be useful for future quantitative color specifications of other flags as well.