Underwater Color Correction Filters
When imaging underwater, the light you are recording is filtered by the water it passes through. Longer wavelength reds and oranges are absorbed until only blue is left. The actual effect is determined by numerous factors, such as light source (sun or artificial), water quality, and the water path. The latter is the distance the light travels through the water. In natural (sun)light, this is the depth of the subject from the surface plus the subject-to-camera distance. For artificial lighting, it is the light-to-subject-to-camera distance. The longer the water path, the greater the filtering effect of the water. In many cases, certain color compensating filters can absorb enough shorter wavelengths to restore better color balance. The difference between corrected and uncorrected color can be dramatic. The use of faster speed films, cameras (video) and lenses will facilitate the use of light absorbing correcting filters.
Pre-processing is required for underwater images due
to poor captured image quality. The following reasons
justify why the pre-processing is necessary for underwater
i. Underwater image degradation is due to specific
transmission properties of light in the water like
absorption and scattering.
ii. Specificity of environment like light changing, water turbidness, and blue hue is more or less predominant
when vehicles move.
iii. Specificity of video captures like unknown rigid scene