Colour cast
Videos
A colour cast is a tint of a particular colour, usually unwanted, that evenly affects a photographic image in whole or in part.
Example of a photo with a uniformly green colour cast due to differential absorption of light before reaching certain depths at sea
The same photo with the colour cast corrected
Blue color cast Compass 1
Blue color cast Compass 2
Photographic filter
Videos
In photography and cinematography, a filter is a camera accessory consisting of an optical filter that can be inserted into the optical path. The filter can be of a square or oblong shape and mounted
Colour cast
…balance settings to choose from. Otherwise, photo editing programs, such as Photoshop, often have built in colour correction facilities. For film, blue filters and amber filters are used to counter casts. Amber filters are used to reduce the blueish tint caused by daylight. Blue filters reduce the orange colour…
Four photographic filters (clockwise from top-left): an infrared hot mirror filter, a polarizing filter, and a UV filter. The larger filter is a polarizer for Cokin-style filter mounts.
Markings on Hoya multicoated skylight filter, identifying size and equivalent Wratten number (1A)
An extreme case: a Nikon D700 with a smashed filter which may have saved the Nikkor lens beneath. Usually, all that can reasonably be expected is protection from scratches, nicks and airborne contaminants.
Infrared filters