15. A system having at least one processor, storage, and a communication platform for generating a unified representation for a document, comprising: a communication platform through which a document can be received; a feature extractor configured for analyzing the received document in accordance with at least one model to form a feature-based vector characterizing the document; a semantic extractor configured for generating a semantic-based representation of the document based on the feature-based vector, wherein the semantic-based representation has a reduced dimension; a reconstruction unit configured for producing a reconstructed feature-based vector based on the semantic-based representation of the document by mapping the semantic-based representation to a feature space of the feature-based vector; a residual feature identifier configured for forming a residual feature-based representation of the document based on the difference between the feature-based vector and the reconstructed feature-based vector; and a unified representation construction unit configured for generating a unified representation for the document based on the semantic-based representation and the residual feature-based representation.
15. A system having at least one processor, storage, and a communication platform for generating a unified representation for a document, comprising: a communication platform through which a document can be received; a feature extractor configured for analyzing the received document in accordance with at least one model to form a feature-based vector characterizing the document; a semantic extractor configured for generating a semantic-based representation of the document based on the feature-based vector, wherein the semantic-based representation has a reduced dimension; a reconstruction unit configured for producing a reconstructed feature-based vector based on the semantic-based representation of the document by mapping the semantic-based representation to a feature space of the feature-based vector; a residual feature identifier configured for forming a residual feature-based representation of the document based on the difference between the feature-based vector and the reconstructed feature-based vector; and a unified representation construction unit configured for generating a unified representation for the document based on the semantic-based representation and the residual feature-based representation. 18. The system of claim 15 , further comprising a feature vector blurring unit configured for forming a blurred feature-based representation of the document by modifying the feature-based vector based on the reconstructed feature-based vector.