1. A video image denoising and enhancing method based on random spray retinex, comprising: structuring spray pixel sets, and tuning parameters related to the random spray retinex based on the spray pixel sets, wherein the parameters include quantity of the spray pixel sets and quantity of pixels; processing video images using the random spray retinex based on tuned parameters; denoising the video images processed by the random spray retinex via low pass filters and blur channels to get a brightness variation calculating formula; obtaining a brightness calculating formula of output images, combined with the brightness variation calculating formula, and calculating brightness variations of three channels via the brightness calculating formula to get local brightness estimating vectors; and fusing the three channels based on the local brightness estimating vectors to get denoised and enhanced video images; wherein, the spray pixel sets are structured by polar coordinates, including n pixels centering at pixel i are represented by Spray k (i), wherein a coordinate of the pixel i is (i x , i y ), and a coordinate of the pixel j, belonging to the spray pixel sets Spray k (i) is (j x , j y ), then the polar coordinates are { j x = i x + ρ · cos ⁡ ( θ ) j y = i y + ρ · sin ⁡ ( θ ) wherein ρ is any value of an interval [0, R], R denotes a spray radius, θ is any value of an interval [0,2π].