1. A method for acquiring classification functions for facial age identification, the method comprising: acquiring a plurality of facial images associated with different ages; assigning the facial images of the plurality of facial images into a plurality of facial image collections based on at least information associated with a plurality of first age groups, wherein each first age group of the plurality of first age groups corresponds to a facial image collection of the plurality of facial image collections, and wherein each facial image collection of the plurality of facial image collections includes one or more of the facial images; for each first age group of the plurality of first age groups, acquiring one or more first facial image collections associated with one or more second age groups older than that first age group as positive samples; and acquiring one or more second facial image collections associated with one or more third age groups younger than that first age group as negative samples; performing training based on at least information associated with the positive samples and the negative samples to determine one or more classification functions for each of the first age groups; determining an estimated age of an additional facial image based on at least information associated with the one or more classification functions.