Assured document and method of making
The present invention teaches techniques for creating scans of documents that are both secure from tamper and that are assured of satisfactory image quality. In particular, a method of producing an assured document is disclosed wherein the documents digital signature is combined with the scan quality in a secure way.
1. A method for producing an assured document comprising:
a) scanning a document to produce a scanned document;
b) providing a representation of the quality of a scan according to image quality metrics obtained from test target image data;
c) calculating a hash of the scanned document;
d) encrypting the representation of the quality of the scan and the hash of the scanned document to form one or more encrypted values; and
e) associating the one or more encrypted values with the scanned document, wherein the scanned document includes an image header and the association of the one or more encrypted values is achieved by storing the one or more encrypted values in the image header.
2. The method of claim 1 , wherein the representation of the quality of the scan further includes at least one of a metric corresponding to the time that the scanned test target was produced and a metric corresponding to the number of documents that were scanned after the scanned test target was produced.
3. The method of claim 1 , wherein representation of the quality of the scan further includes one or more test target image fragments.
4. The method of claim 1 , wherein providing a representation of the quality of the scan further includes comparing the representation of the quality of the scan to quality threshold values.
5. The method of claim 1 wherein the image quality metrics obtained from the scanned document image data comprise one or more measurements of resolution, noise, dynamic range, or color fidelity.
6. The method of claim 1 further comprising comparing the image quality metrics against threshold tolerances.
7. The method of claim 1 further comprising aligning the test target using fiducials.
8. A method for producing an assured document comprising:
a) scanning a document to produce a scanned document;
b) providing a representation of the quality of a scan according to image quality metrics obtained from test target image data;
c) calculating a hash of the scanned document;
d) encrypting the representation of the quality of the scan and the hash of the scanned document to form one or more encrypted values; and
e) associating the one or more encrypted values with the scanned document,
wherein the scanned document has a filename and the association of the one or more encrypted values is achieved by storing the one or more encrypted values in the filename.
9. A method for producing an assured document comprising:
a) scanning a document to produce a scanned document;
b) providing a representation of the quality of a scan according to image quality metrics obtained from test target image data;
c) calculating a hash of the scanned document;
d) encrypting the representation of the quality of the scan and the hash of the scanned document to form one or more encrypted values; and
e) associating the one or more encrypted values with the scanned document, wherein providing a representation of the quality of the scan further comprises detecting a barcode that identifies the test target.