Fading Colours: Investigating Spectral Attenuation in Underwater Photography with Distance

Underwater imaging is susceptible to inherent spectral attenuation of colour, which becomes more distorting with growing distance from the camera. In this paper, the effect of object distance on spectral attenuation is examined by imaging a DGK colour Calibration Card at differing distances in air and in water. The HSI (Hue, Saturation, Intensity) colour model is applied in the analysis for quantitative measurement of spectral attenuation. The obtained results demonstrate a systematic decline in intensity and saturation, accompanied by a pronounced hue shift, particularly within the red and yellow spectra. The proposed distance-aware correction model effectively restores colour fidelity in underwater images, achieving an average reduction in saturation distortion of over 30% and improved perceptual neutrality of reference patches across distances from 1m to 3m. These findings confirm that the applied approach mitigates colour degradation due to spectral absorption and scattering, thus enabling consistent colour restoration in shallow aquatic environments and providing a baseline for distance-based colour correction in underwater imagery.