Electronic document classification comprising providing training documents sorted into classes; linear programming including selecting inputs which maximize an output, given constraints on inputs, the output maximized being a difference between: a. first estimated probability that a document instance will be correctly classified, by a classifier corresponding to given inputs, as belonging to its own class, and b. second estimated probability that document instance will be classified, by the classifier, as not belonging to its own class; and classifying electronic document instances into classes, using a preferred classifier corresponding, to the inputs selected by the linear programming. A computerized electronic document forgery detection method provides training documents and uses a processor to select value-ranges of non-trivial parameters, such that selected values-range(s) of parameters are typical to an authentic document of given class, and atypical to a forged document of same class.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A computerized method for electronic document classification, the method comprising: providing training documents sorted into a plurality of classes; using a processor to perform linear programming including selecting input values which maximize an output value, given specific constraints on the input values, wherein the output value maximized is a difference between: a. a first estimated probability that a document instance will be correctly classified, by a given classifier corresponding to given input values, as belonging to its own class, and b. a second estimated probability that the document instance will be classified, by the given classifier, as belonging to a class other than its own class; and classifying electronic document instances into the plurality of classes, using at least one preferred classifier corresponding to the input values selected by said linear programming including storing an indication of said classifying in computer memory. 2. A method according to claim 1, wherein some electronic document instances are classified as belonging to none of the plurality of classes. 3. A method according to claim 1 wherein said training documents sorted into a plurality of classes are sorted by a human supervisor and said own class comprises a class to which a training document belongs, as determined by the human supervisor. 4. A method according to claim 1, wherein each electronic document instance includes at least one digital scan, using at least one illumination, of a physical document. 5. A method according to claim 1, wherein said classifying uses said preferred classifier in conjunction with available partial information regarding correspondence between electronic document instances and the plurality of classes. 6. A method according to claim 5, wherein said partial information includes information read from an electronic document instance's machine readable zone. 7. A method according to claim 1, wherein said input values comprise weights used to compute linear combinations of functions of features derived from individual electronic document instances. 8. A method according to claim 7, wherein at least one feature derived from at least one individual electronic document instance characterizes a local patch within the individual electronic document instance. 9. A method according to claim 8, wherein at least one feature derived from at least one individual electronic document instance comprises a texture feature. 10. A method according to claim 8, wherein at least one feature derived from at least one individual electronic document instance comprises a color moment feature. 11. A method according to claim 8, wherein at least one feature derived from at least one individual electronic document instance comprises a ratio between a central tendency of at a color characterizing at least a portion of the electronic document instance, and a measure of spread of the color. 12. A method according to claim 11 wherein said color is expressed in terms of least one channel in a color space. 13. A method according to claim 1 wherein each feature is associated with at least one k-nearest-neighbors weak classifier. 14. A method according to claim 1 and also comprising electronically determining whether each of a stream of electronic document instances are forgeries, by performing electronic forgery tests specific to individual classes from among said plurality of classes, on individual electronic document instances in said stream which have been classified by said preferred classifier, as belonging to said individual classes respectively. 15. A method according to claim 7, wherein said functions include probabilities that an individual document instance belongs to a given class given that the individual document instance is characterized by a particular feature derived from individual electronic document instances. 16. A method according to claim 15 wherein said constraints include at least one constraint whereby a pair of said linear combinations, corresponding to different classes, differ by at least a predetermined margin. 17. A method according to claim 15 wherein said constraints include at least one constraint whereby a pair of said linear combinations, corresponding to different classes, differ by at least a predetermined margin but for a slack variable characterizing an individual electronic document and selected to be large if the individual electronic document is an outlier in its class. 18. A system for electronic document classification operative in conjunction with training documents sorted into a plurality of classes, the system comprising: computerized apparatus using a processor for performing linear programming including selecting input values which maximize an output value, given specific constraints on the input values, wherein the output value maximized is a difference between: a. a first estimated probability that a document instance will be correctly classified, by a given classifier corresponding to given input values, as belonging to its own class, and b. a second estimated probability that the document instance will be classified, by the given classifier, as belonging to a class other than its own class; and apparatus for classifying electronic document instances into the plurality of classes, using at least one preferred classifier corresponding to the input values selected by said linear programming. 19. A method according to claim 4, wherein each electronic document instance includes a plurality of scans, using a plurality of illuminations, of a physical document. 20. A computer program product, comprising a computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a computerized method for electronic document classification, the method comprising: providing training documents sorted into a plurality of classes; using a processor to perform linear programming including selecting input values which maximize an output value, given specific constraints on the input values, wherein the output value maximized is a difference between: a. a first estimated probability that a document instance will be correctly classified, by a given classifier corresponding to given input values, as belonging to its own class, and b. a second estimated probability that the document instance will be classified, by the given classifier, as belonging to a class other than its own class; and apparatus for classifying electronic document instances into the plurality of classes, using at least one preferred classifier corresponding to the input values selected by said linear programming including storing an indication of said classifying in computer memory.