Color theory primary colors work at all is that the imperfect pigments being used have sloped absorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and
Judo of national judo associations. The IJF is responsible for organising international competition and hosts the World Judo Championships and is involved in running the Olympic Judo events. Judo is a hierarchical art, where seniority of judoka is designated by what is known as the - ranking system. This system was developed by Jigoro Kano and was based on the ranking system in the board game Go. Beginning students progress through kyu grades towards dan grades. A judoka's position within the kyu-dan ranking system is displayed by the color of their belt. Beginning students typically wear a white belt, progressing through