1. A method performed by one or more server devices, the method comprising: performing, using one or more processors associated with the one or more server devices, a wavelet transform on a plurality of images; selecting, using one or more processors associated with the one or more server devices, a particular number of highest magnitude wavelength coefficients for a particular image of the plurality of images; comparing, using one or more processors associated with the one or more server devices, a number of same wavelength coefficients of two particular images of the plurality of images to identify a set of duplicate images; extracting, using one or more processors associated with the one or more server devices, one or more labels associated with images in the identified set of duplicate images; combining, using one or more processors associated with the one or more server devices, selected ones of the one or more extracted labels; and assigning, using one or more processors associated with the one or more server devices, the combined labels to at least some of the images of the identified set of duplicate images.