1. A method performed by one or more processors configured with computer-executable instructions, the method comprising: extracting one or more classification image features from an image for classification; based on a similarity relationship between each classification image feature and each visual word in a pre-generated visual dictionary, quantifying each classification image feature by multiple visual words in the visual dictionary and determining a similarity coefficient between each classification image feature and each visual word after the quantifying; based on one or more similarity coefficients of each visual word corresponding to different classification image features, determining a weight of each visual word to establish a classification visual word histogram; inputting the classification visual word histogram into an image classifier; and using an output of the inputting to determine a classification of the image for classification.