Systems and methods for assessing standards for mobile image quality
Methods are provided for defining and determining a formal and verifiable mobile document image quality and usability (MDIQU) standard, or Standard for short. The Standard ensures that a mobile image can be used in an appropriate mobile document processing application, for example an application for mobile check deposit. In order to quantify the usability, the Standard establishes 5 quality and usability grades. A mobile image is first tested to determine if the quality is sufficient to obtain content from the image by performing multiple different image quality assessment tests. If the image quality is sufficient, one or more document usability computations are made to determine if the document or content in the image is usable by a particular application. A ranking is then assigned to the image based on the results of the tests which is indicative of the quality and usability of the image.
1. A non-transitory computer-readable medium containing instructions which, when executed by a computer, perform a process comprising:
receiving an image of a document captured by a mobile device;
processing the image to determine a set of image quality assurance (IQA) scores;
performing a computation relating to the set of IQA scores to obtain at least one compound IQA score, wherein the computation includes combining a subset of strongly correlated IQA scores in the set of IQA scores into a compound IQA score, and wherein the subset of strongly correlated IQA scores is associated with a common image defect;
determining if the image meets a predetermined standard of image quality based on the at least one compound IQA score; and
if the image meets the predetermined standard of image quality:
assessing a usability score of the document in the image to ensure that the document belongs to one of a set of supported categories of documents; and
outputting the at least one compound IQA score and the usability score;
otherwise, characterizing the image as unusable.
2. The non-transitory computer-readable medium of claim 1 , wherein the set of IQA scores includes one or more of: an out-of-focus ( 00 F) score, a shadow score, a small-image-size score, a view-skew score, a plain-skew score, a warpage score, a low-internal-contrast score, a reflection score, a cut-corners score, a cut-sides score, a busy-background score, and a low-external-contrast score.
3. The non-transitory computer-readable medium of claim 1 , wherein if the image meets the predetermined standard of image quality, the process further comprises outputting an overall image quality score of the image.
4. The non-transitory computer-readable medium of claim 1 , wherein the at least one compound IQA score includes a first compound IQA score to ensure the document in the image is detectable and a second compound IQA score to ensure that contents of the document is sufficiently legible.
5. The non-transitory computer-readable medium of claim 1 , wherein performing the computation relating to the set of IQA scores to obtain at least one compound IQA score includes computing a linear combination of the set of IQA scores.
6. The non-transitory computer-readable medium of claim 1 , wherein determining if the image meets a predetermined standard of image quality based on the at least one compound IQA score includes comparing the at least one compound IQA score against at least on threshold value.
7. The non-transitory computer-readable medium of claim 1 , wherein assessing the usability score of the document includes:
capturing a set of critical fields from the image of the document; and
determining the usability score based on the set of captured critical fields.
8. The non-transitory computer-readable medium of claim 1 , wherein the set of supported categories of documents includes one or more of: US checks, remittance coupons, credit card bills, and driver's licenses.
9. The non-transitory computer-readable medium of claim 1 , wherein characterizing the image as unusable includes assigning the image with the lowest rank of a set of predetermined ranks.
10. The non-transitory computer-readable medium of claim 1 , wherein performing the computation relating to the set of IQA scores to obtain the at least one compound IQA score includes combining the set of IQA scores into two compound IQA scores.
11. The non-transitory computer-readable medium of claim 10 , wherein the two compound IQA scores includes a first compound IQA score to ensure that the document is detectable in the image of the document and second compound IQA score to ensure that the document in the image is fully legible.
12. The non-transitory computer-readable medium of claim 1 , wherein the common image defect is the low-contrast of the image.
13. A system for assessing mobile image qualities of a document, comprising:
a processor; and
a memory coupled to the processor to store instructions for assessing qualities of mobile images of documents;
wherein the processor is configured to perform a process of:
receiving an image of a document captured by a mobile device;
processing the image to determine a set of image quality assurance (IQA);
performing a computation relating to the set of IQA scores to obtain at least one compound IQA score, wherein the computation includes combining a subset of strongly correlated IQA scores in the set of IQA scores into a compound IQA score, and wherein the subset of strongly correlated IQA scores is associated with a common image defect;
determining if the image meets a predetermined standard of image quality based on the at least one compound IQA score; and
if the image meets the predetermined standard of image quality:
assessing a usability score of the document in the image to ensure that the document belongs to one of a set of supported categories of documents; and
outputting the at least one compound IQA score and the usability score;
otherwise, characterizing the image as unusable.
14. The system of claim 13 , wherein the set of IQA scores includes one or more of: an out-of-focus (OOF) score, a shadow score, a small-image-size score, a view-skew score, a plain-skew score, a warpage score, a low-internal-contrast score, a reflection score, a cut-corners score, a cut-sides score, a busy-background score, and a low-external-contrast score.
15. The system of claim 13 , wherein if the image meets the predetermined standard of image quality, the process further comprises outputting an overall image quality score of the image.
16. The system of claim 13 , wherein the at least one compound IQA score includes a first compound IQA score to ensure the document in the image is detectable and a second compound IQA score to ensure that contents of the document is sufficiently legible.
17. The system of claim 13 , wherein performing the computation relating to the set of IQA scores to obtain at least one compound IQA score includes computing a linear combination of the set of IQA scores.
18. The system of claim 13 , wherein determining if the image meets a predetermined standard of image quality based on the at least one compound IQA score includes comparing the at least one compound IQA score against at least on threshold value.
19. The system of claim 13 , wherein assessing the usability score of the document includes:
capturing a set of critical fields from the image of the document; and
determining the usability score based on the set of captured critical fields.
20. The system of claim 13 , wherein the set of supported categories of documents includes one or more of: US checks, remittance coupons, credit card bills, and driver's licenses.
21. The system of claim 13 , wherein characterizing the image as unusable includes assigning the image with the lowest rank of a set of predetermined ranks.
22. The system of claim 13 , wherein performing the computation relating to the set of IQA scores to obtain the at least one compound IQA score includes combining the set of IQA scores into two compound IQA scores.
23. The system of claim 22 , wherein the two compound IQA scores includes a first compound IQA score to ensure that the document is detectable in the image of the document and second compound IQA score to ensure that the document in the image is fully legible.
24. The system of claim 13 , wherein the common image defect is the low-contrast of the image.