Analysis of Water Turbidity Using Image Processing and Polarimetry Based on Light Intensity Patterns

Abstract

Turbidity is an essential parameter in assessing water quality because it is directly related
to the concentration of suspended particles and the medium’s ability to transmit light. Conventional
turbidity measurements using turbidimeters require specialized laboratory instruments, creating the
need for a simpler and more accessible alternative method. This study aims to analyze the turbidity
levels of three water types pure water, tap water, and contaminated water—through a combination
of digital image processing and polarization-based light intensity analysis. Images of each sample
were captured using a smartphone camera under controlled geometric conditions and processed in
ImageJ to obtain optical parameters, including Mean Gray Value and relative transmission (T₍rel₎).
In addition, each sample was examined using a polarimeter to identify intensity patterns of bright
dark–bright (T–G–T) and dark–bright–dark (G–T–G) as indicators of light scattering. The results
show a consistent increase in Mean Gray Values from pure water (108.005), to tap water (130.365),
and contaminated water (184.951), indicating increased light scattering with higher turbidity. The
T₍rel₎ values follow a similar trend with ratios of 1 : 1.21 : 1.71. Polarimetric measurements reveal
that the T–G–T and G–T–G patterns appear clearly in pure water, shift significantly in tap water,
and disappear completely in contaminated water due to total depolarization. These findings
demonstrate that the combination of digital image analysis and light polarization offers a low-cost,
rapid, and sufficiently sensitive alternative for identifying water turbidity without the need for
conventional laboratory instruments.