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g_robinson

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  1. Hi Jack, Yes you can determine colours from many black and white photos! We were asked at the Doerner Institut in Munich to do this for an organisation wishing to restore their Berlin property to its original colours from b&w photos. We didn't have the resources to take them up on the challenge at the time. About one in a million Britons suffer complete colour blindness and only see in black and white. To compensate they become very sensitive to shades of grey, and with constant exposure to others telling them what colour objects are, they learn to recognise colours independently. A bizarre consequence is that they can also correctly identify colours from original 405 line monochrome TV transmissions, or from monochrome cine films! As another member suggested, this arises from the interplay of known colours upon unknown colours. A deep blue dress reflects very differently onto rosy cheeked woman, than a red dress. The corner of a building taken at 45° with direct sunlight at 5780K on one side, and 8000K blue sky on the shadow side will produce a ratio of densities that depend on the colour of the wall paint. For a given set of conditions that include the level of cloud cover, and geometry of the camera, sun & building, then by varying the building colour only, the density ratio of the two wall faces will change! But who has access to all that data, and can calibrate out the chemistry of the negative and paper too? We didn't, so we rejected the request. However, it might be simpler to find any one of the 60 fully colour blind individuals in the U.K., and ask them to cast their eye over the photos. If the masonry paint is not too pale there's a chance that they can identify the colour from experience. PS. Here's a related topic: Is it possible to identify colours in a scene when low pressure sodium lighting is the only illumination present?
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