Method for Adaptively Detecting Low Contrast Image of V-prism Refractometer

It is a critical issue of glass refractive index measurement that enhancing low contrast slit image. In order to solve this problem, the paper proposes a solution that is feasible and adaptive to enhancing low contrast image in engineering. The CLAHE algorithm is used to globally preprocess the slit image acquired by CCD in the meantime and adaptive smoothing filtering is used for filtering. The improved stretching window is used to suppress the brightness of the single line in the slit, and enhance the brightness of the slit image to improve the extraction accuracy of the single line. The experimental results show that the accuracy of glass refractive index measurement can be improved to ±5×10−6 in the case of low contrast image, which provides a new method of low brightness and low contrast for improving the measurement accuracy of V -prism refractometer and has a significant in its high precision measurement.