make a poster of the the pure brightness festival, a river runs throught the city, some little boat in the river, boat, poets, blue turbulence, light rain, raindrops fall into the river, paper umbrellas and pedestrians, bright background, clear contour light, warm cyan, saturated color scheme, long shot, quixel megascan rendering, chuanxi style, dreamy mist, ultra hight definition, ray tracing