German artist Katharina Fritsch's idea of a huge cockerel in ultramarine blue is aimed at injecting colour into the square.

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Yet even the great Venetian colourists were prey to pigments' tricks: vermilion reds that blacken and ultramarine skies that fade.

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More aptly chosen is a second sunflower image of 1887 from the Metropolitan Museum of Art, depicting two slightly wilted blossoms lying on a rich ultramarine blue tablecloth.

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Stretching east from the pass is a long valley pocked with ultramarine lakes, watched over by sheer walls of striated granite that are striped with the wispy white of flowing waterfalls.

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Known collectively as the Crater Lakes, their 65m deep, tranquil ultramarine waters belie a violent past: both were formed anywhere from 17, 000 to 10, 000 years ago by a massive volcanic eruption.

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Large-scale protagonists occupy a shallow frieze across the canvas, with a substantial volume of space evoked by means of gesture, architectural settings, glimpses of landscape and, above all, relationships of opulent hues burgundy, scarlet, salmon, creamy off-whites, dull greens, saturated ultramarine, chalky cerulean.

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