Quantitative Determination Of Ph In Water Based On Digital Image Colorimetry

Water resource is an important natural resource,and the pH value is one of the key factors that determine the health of a water environment,it could intuitively reflect the change of water quality.Therefore,the pH value of a water environment is an important variable for water quality assessment.The common means of detecting the pH of a water body are visual colorimetry,photometry,and potentiometry,and there are four key points for the application of these detection methods: cost,easy operation,portability,and accuracy.With the development of imaging equipment and image processing technology,a new colorimetric analysis method has emerged,that is,digital image colorimetry(DIC),which is widely used for quantitative analysis of color because of its simple operation and low-cost.When DIC is applied to the detection of water p H,the economic costs would be saved,the detection process would be simplified.And image analysis can be used instead of visual interpretation to identify and extract the color information on the pH sensing strips,weakening the influence of human factors,and quantifying the color information on the sensing strips.To improve detection accuracy and achieve rapid and quantitative detection of pH in water.The key of DIC's application is to select suitable color features and overcome the effects of lighting conditions.To address the above-mentioned problems,a quantitative prediction model of pH value in water is established based on the digital image colorimetry.It lays a foundation for the quantitative detection of digital image colorimetry applied to other water quality parameters.Specifically,the research contents and results are as follows:(1)The images were obtained by photographing the pH strips in aqueous solution.The color information was then extracted from the images,and its relationship with pH was explored in both red,green,blue(RGB)and hue,saturation,value(HSV)color spaces.It was found that the hue of HSV space has a good correlation with the pH,despite under the different ambient illumination.The color of the sensing strips was then quantified by transforming the color to hue and a reverse model to predict pH of water was established.(2)This paper discusseed the effects of different lighting conditions on this model.The experimental results showed that the model has good adaptability to lighting conditions.Subsequently,the lake water samples,drinking water samples,tap water samples,and other types of water samples and simulated complex pH water environments were used to verify this model,the relevant experiments showed that this model is effective for the detection of different samples,at the same time,the change trend of the simulated complex pH water environments could also be detected by the model.(3)The quantitative detection model of pH in water based on digital image colorimetry was applied to real lake water.The results showed that the model could predict the pH of the lake water,it meant that the detection model is applicable to the waters in natural scenes.