The invention relates to a non-reference screen content 
image quality evaluation method based on multiple scales. The method comprises the following steps: S1, converting a distorted image from an RGBcolor space to an LMN 
color space, amplifying an L component by using a bicubic 
algorithm, and extracting edge features of the distorted image by using an imaginary part of a 
Gabor filter; s2, amplifying the grey-
scale map of the distorted image by using a bicubic 
algorithm, and extracting the structural features of the distorted image by using a Scharr filter and a local binary pattern; s3, extracting brightness features of the distorted image by using a local 
normalization algorithm; s4, taking the obtained three features as training data, and training an 
image quality evaluation model by utilizing 
random forest regression; and S5, according to the steps S1-S3, obtaining edge features, structure features and brightness features of the to-be-detected image, and predicting the 
quality score of the to-be-detected image by using the trained 
image quality evaluation model. According to the invention, the reference-screen-free content image quality evaluation performance can be significantly improved.