A proposal on the colors of the flags of the current autonomous communities and cities of Spain

According to the current legal regulations, the flags of 8 of the 19 autonomous communities and cities in Spain have only qualitative specifications of their colors. We have performed quantitative color measurements under fixed experimental conditions (e.g. illuminant D65, CIE 1964 standard colorimetric observer) for 3 collections of the 19 mentioned flags: One acquired by internet and two existing in high institutions of the Spanish State in Madrid (Supreme Court and Constitutional Court). The 52 main colors of the flags of the Supreme Court and Constitutional Court are relatively similar (average color difference of 6.2 CIELAB units). Therefore, we propose their average colors (with the exception of the blue color of the diagonal stripe of the flag of Galicia and the red and green stripes of the flag of La Rioja), with a tolerance of 10 CIELAB units, as a reference for future studies and standardization. The average color difference between our proposal and the colors of the purchased flags or those specified in current legislation is very high (about 20 CIELAB units). Most colors of the flags in the Supreme Court and Constitutional Court are located in 6 regions of the CIELAB color space we can name as white, black, red, yellow, green and blue. In all our color comparisons of flags from different collections, hue difference was the smallest component (<20%) of total CIELAB color difference.