Colorimetric Analysis For Quanttitative Detection Based On The Dominant Wavelength And The Complementary Wavelength Of Colors

As a rapid and quantitative analysis method based on the chromogenic reactions, the colorimetric method is widely used in the fields of biology, medicine, chemistry, environment and other aspects. Compared with other colorimetric methods, the digital image colorimetry has the advantages of simple operation, less time consuming, low cost and relatively higher detection accuracy, which has attracted extensive attention to researchers. This colorimetric method adopts different color space according to the characteristics of colors of the chromogenic reaction. For some chromogenic reactions with single tonal, the process of image analysis is relatively simple; However, for these reactions that the hue of the chromogenic products changes along with the change of the quantity to be measured, researchers have given some different colorimetric methods which have certain complexity and limitation in practical applications. This paper proposed a new digital image colorimetric method based on the dominant wavelength and the complementary wavelength of colors which can quantify the color information of images by wavelength of colors and can make quantitative analysis of the chromogenic reactions with the change of hue by the wavelength information.The main contents of this paper are as follows.1?The CIE(Commission Internationale de L'Eclairage) colorimetric system and the conversion between sRGB(Standard RGB) color space and CIE colorimetric system were studied. An algorithm of transformation from the image's RGB color information to its color's dominant wavelength or complementary wavelength was proposed. The MATLAB program was composed to achieve the extraction of the wavelength information in an image.2 ? The MATLAB program, which achieved the extraction of the wavelength information in an image, was utilized to make quantitative analysis of the chromogenic reactions. The quantitative detection of the p H value was realized with the color's dominant wavelength and the detection of the nitrite with the color's complementary wavelength. There is a linear relationship between the p H value and the color's dominant wavelength of its chromogenic products in the range of 4.0~7.0 and 7.5~10.0 of p H, respectively. There is a favorable linear relationship between the concentration(510~40 mg/L) of the nitrite and the color's complementary wavelength of its chromogenic products, combining with the Green value of the color which can enlarge the scope of detection compared with the traditional absorption spectrometry.3 ? The program for processing images was further improved, and comparison of wavelength of the chromogenic results based on the cuvette and filter paper before and after the improvement of program was made, respectively. Finally, the MATLAB program which can extract wavelength of the image was ported to the Lab VIEW, and with its relevant functions the program was packaged into the software, which can be used conveniently for users compared with the MATLAB.