Characterizing items of currency

1. A validation apparatus comprising:

at least one broadband source for illuminating an item of currency;

at least three specified physical filters, wherein each of the at least three specified physical filters has a transmission spectrum similar to at least one approximating function for reconstructing a predetermined reference spectrum, the reference spectrum being similar to an emission spectrum of at least a portion of a document, wherein each of the at least three specified filters filter light emitted from each respective broadband source such that the resulting transmission spectrum is similar to the predetermined reference spectrum;

at least one receiver for receiving filtered light emitted from the at least one broadband source;

a transportation unit for transporting the item of currency within the validation apparatus;

wherein the at least three specified physical filters are positioned between the at least one broadband source and the at least one receiver; and

wherein the light received by the at least one receiver is at least one of light reflected by or light transmitted through the item of currency.

2. A validation apparatus according to claim 1 wherein the resulting light filtered by the at least three specified filters is at least one of the visible or non-visible light.

3. A validation apparatus according to claim 1 wherein each of the broadband sources is energized in a predetermined manner.

4. A validation apparatus according to claim 1 wherein the transportation unit is arranged to include a plurality of transportation units configured to form a continuous transportation path.

5. A validation apparatus according to claim 1 wherein the transportation unit is arranged to transport the currency item past the at least one broadband source and the at least one receiver.

6. A validation apparatus according to claim 1 wherein the item of currency is classified using the received light from each of the at least filtered broadband sources.

7. A validation apparatus according to claim 6 wherein the classification of the currency item is performed in a function space.

8. A validation apparatus according to claim 6 wherein the classification of the currency item is performed in a reconstruction space.

9. A validation apparatus according to claim 1 further comprising a processor.

10. A validation apparatus according to claim 9 wherein the processor is configured for classifying the currency item.

11. A validation apparatus according to claim 1 further comprising a memory unit operatively coupled to the processor.

12. A validation apparatus according to claim 11 wherein the memory unit is configured to store a classifier used to classify at least one currency item.

13. A validation apparatus according to claim 1 wherein at least one of the at least three specified filters has an emission spectrum having a band of at least 50 nanometers.

14. A validation apparatus according to claim 13 wherein the at least one of the at least three specified filters has an emission spectrum having a large band and at least two lobes.

15. The validation apparatus of claim 10 , wherein the at least one broadband source is at least 3 broadband sources and the at least 3 specified physical filters are each coupled to one of the at least 3 broadband sources.

16. The validation apparatus of claim 1 , wherein the at least one receiver is at least 3 receivers and wherein the at least 3 specified physical filters are each coupled to one of the at least 3 receivers.

17. A validation apparatus comprising:

a plurality of common sources for illuminating an item of currency, wherein at least one common source has an emission spectrum similar to at least one of Red light, Blue light, Green light or infrared light;

at least one specified source for illuminating the item of currency, wherein the emission spectrum of the at least one specified source is similar to a portion of an emission spectrum of at least an item of currency to be classified by the validation apparatus;

a receiver for receiving light emitted from at least one of the plurality of common sources or the at least one specified source;

a transportation unit for transporting the item of currency within the validation apparatus;

wherein the validation apparatus classifies the currency item based in part on at least one of light reflected on or transmitted through the currency item.

18. A validation apparatus according to claim 17 wherein one of the common sources has an emission band of between 640 nm-700 nm.

19. A validation apparatus according to claim 17 wherein the at least one specified source has an emission spectrum similar to a particular item of currency to be classified by the validation apparatus.

20. A validation apparatus according to claim 17 wherein the at least one specified source is an LED constructed from a plurality of phosphors.

21. A apparatus according to claim 17 wherein the at least one specified source is a broadband source with a specified physical filter coupled thereto such that the transmission spectrum from the specified physical filter is similar to at least one currency item to be classified by the validation apparatus.

22. A validation apparatus according to claim 17 wherein the at least one specified source is a retrofit component of the validation apparatus.

23. A validation apparatus comprising:

a plurality of common sources for illuminating an item of currency, wherein at least one common source has an emission spectrum similar to at least one of Red light, Blue light, Green light or infrared light;

at least one specified source for illuminating the item of currency, wherein the emission spectrum of the at least one specified source is similar at least one approximating function for reconstructing a predetermined reference spectrum;

a receiver for receiving light emitted from at least one of the plurality of common sources or the at least one specified source; and

a transportation unit for transporting the item of currency within the validation apparatus;

wherein the validation apparatus classifies the currency item based in part on at least one of light reflected on or transmitted through the currency item.

24. A validation apparatus according to claim 23 wherein one of the common sources has an emission band of between 640 nm-700 nm.

25. A validation apparatus according to claim 23 wherein the at least one specified source has an emission spectrum similar to a particular item of currency to be classified by the validation apparatus.

26. A validation apparatus according to claim 23 wherein the at least one specified source is an LED constructed from a plurality of phosphors.

27. A apparatus according to claim 23 wherein the at least one specified source is a broadband source with a specified physical filter coupled thereto such that the transmission spectrum from the specified physical filter is similar to at least one currency item to be classified by the validation apparatus.

28. A validation apparatus according to claim 23 wherein the at least one specified source is a retrofit component of the validation apparatus.