The image below is a single 20-second exposure taken with a red-green-blue filter.

下图是用红-绿-蓝滤光片拍摄的单一20秒曝光照片。

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Banff Springs Hotel with light blue filter emphasizes the coldness of winter (Monochromatic color).

班芙泉酒店，用浅蓝色滤光镜强调冬天的寒冷单一色。

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DGD series cartridges are manufactured from 100% pure polypropylene and are sized for use in our big blue filter housings.

DGD系列的滤筒根据我们公司的蓝色过滤器量身定做，该设备使用100%的聚丙烯进行加工生产。

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The first permanent colour photograph was taken by Thomas Sutton who was working with Clerk Maxwell and is a composite of three black and white pictures, each one taken through a red, green or blue filter.

BBC: Pioneering colour photography

Philips' solution is to combine two blue and one red element, but use a green phosphor filter to convert one of the blue LEDs to green.

ENGADGET

In case you don't have your smartphone app handy, the taps are equipped with LED lights to show the water's filter status as well -- blue means clean, yellow means not so much and red means you should probably get a new filter, pronto.

ENGADGET