Comparing documents using a trusted source

1. A method comprising:

performing document analysis of a first document image of a related document;

performing a first character recognition of the first document image;

comparing the first document image with a second document image of a reference document based on results of the first character recognition;

transforming the first document image based on the comparison of the first document image and the second document image; and

performing a second character recognition of the transformed first document image using a reference dictionary generated in view of the reference document.

2. The method of claim 1 , further comprising calculating differences between the related document and the reference document based on results of the second character recognition.

3. The method of claim 1 , wherein the comparing the first document image with the second document image comprises comparing at least a part of a first layout and at least a part of a first text produced by the first character recognition of the first document image to at least a part of a second layout and at least a part of a second text of the second document image.

4. The method of claim 3 , wherein the part of the first text and the part of the second text comprise words having at least a predefined number of characters, and wherein the comparing further comprises calculating an edit distance between corresponding words.

5. The method of claim 1 , wherein the first document image comprises an image of a page of a document.

6. The method of claim 1 , wherein transforming comprises performing a linear transformation of the second document image based on positions of three points within each of the first document image and the second document image.

7. The method of claim 1 , wherein the reference dictionary comprises words from only a specific text block of the second document image.

8. A system comprising:

a memory;

a processor coupled to the memory, the processor configured to:

perform document analysis of a first document image of a related document;

perform a first character recognition of the first document image;

compare the first document image with a second document image of a reference document based on results of the first character recognition;

transform the first document image based on the comparison of the first document image and the second document image; and

perform a second character recognition of the transformed first document image using a reference dictionary generated in view of the reference document.

9. The system of claim 8 , wherein the processor is further configured to calculate differences between the related document and the reference document based on results of the second character recognition.

10. The system of claim 8 , wherein comparing the first document image with the second document image comprises comparing at least a part of a first layout and at least a part of a first text produced by the first character recognition of the first document image to at least a part of a second layout and at least a part of a second text of the second document image.

11. The system of claim 10 , wherein the part of the first text and the part of the second text comprise words having at least a predefined number of characters, and wherein the comparing further comprises calculating an edit distance between corresponding words.

12. The system of claim 8 , wherein the first document image comprises an image of a page of a document.

13. The system of claim 8 , wherein transforming comprises performing a linear transformation of the second document image based on positions of three points within each of the first document image and the second document image.

14. The system of claim 8 , wherein the reference dictionary comprises words from only a specific text block of the second document image.

15. A computer-readable non-transitory storage medium comprising executable instructions that, when executed by a computing device, cause the computing device to perform operations comprising:

performing document analysis of a first document image of a related document;

performing a first character recognition of the first document image;

comparing the first document image with a second document image of a reference document based on results of the first character recognition;

transforming the first document image based on the comparison of the first document image and the second document image; and

performing a second character recognition of the transformed first document image using a reference dictionary generated in view of the reference document.

16. The computer-readable non-transitory storage medium of claim 15 , further comprising calculating differences between the related document and the reference document based on results of the second character recognition.

17. The computer-readable non-transitory storage medium of claim 15 , wherein comparing the first document image with the second document image comprises comparing at least a part of a first layout and a part of a first text produced by the first character recognition of the first document image to at least a part of a second layout and a part of a second text of the second document image.

18. The computer-readable non-transitory storage medium of claim 17 , wherein the part of the first text and the part of the second text comprise words having at least a predefined number of characters, and wherein the comparing further comprises calculating an edit distance between corresponding words.

19. The computer-readable non-transitory storage medium of claim 15 , wherein transforming comprises performing a linear transformation of the second document image based on positions of three points within each of the first document image and the second document image.

20. The computer-readable non-transitory storage medium of claim 15 , wherein the reference dictionary comprises words from only a specific text block of the second document image.