Systems and methods for classifying objects in digital images captured using mobile devices

1. A method, comprising:

receiving or capturing a digital image using a mobile device;

using a processor of the mobile device to:

determine whether an object depicted in the digital image belongs to a particular object class among a plurality of object classes based on feature-space discrimination wherein the feature space discrimination utilizes one or more of support-vector-machine (SVM) techniques, transductive classification techniques, and maximum entropy discrimination (MED) techniques;

determine one or more object features of the object based at least in part on the particular object class at least partially in response to determining the object belongs to the particular object class;

build or select an extraction model based at least in part on the one or more determined object features; and

extract data from the digital image using the extraction model, the extracting comprising detecting one or more lines of text in the object, and the detecting comprising:

projecting the digital image onto a single dimension;

projecting each color channel of the digital image onto a single channel along the single dimension

determining a distribution of light and dark areas along the projection;

determining a plurality of dark pixel densities, each dark pixel density corresponding to a position along the projection;

determining whether each dark pixel density is greater than a probable text line threshold; and

designating each position as a text line upon determining the corresponding dark pixel density is greater than the probable text line threshold.

2. The method as recited in claim 1 , wherein extracting the data using the extraction model further comprises performing optical character recognition (OCR), wherein the OCR is performed on a selected portion of the digital image excluding one or more portions of the received or captured image.

3. The method as recited in claim 1 , wherein the feature space discrimination utilizes support-vector-machine (SVM) techniques.

4. The method as recited in claim 1 , wherein the feature space discrimination comprises identifying a hyperplane separating the plurality of object classes in an N-dimensional feature space.

5. The method as recited in claim 1 ,

wherein the extraction model is built, wherein building the extraction model comprises:

mapping one or more of a feature vector, a list of feature vectors and a feature matrix to one or more of the object features; and

associating at least one metadata label with each mapped object feature.

6. The method as recited in claim 1 , further comprising: training the extraction model based on one or more additional object features of at least one additional object belonging to the object class.

7. The method as recited in claim 6 , wherein the extraction model is trained using the processor of the mobile device according to a support vector machine (SVM) technique; and the method further comprising storing and/or exporting the trained extraction model.

8. The method as recited in claim 1 , further comprising:

building a new extraction model based on some or all of the determined object features; and

extracting data from the digital image using the new extraction model.

9. The method as recited in claim 1 , further comprising:

performing OCR on some or all of the extracted data.

10. The method as recited in claim 1 , further comprising:

associating a plurality of metadata labels with the digital image based on the particular object class, wherein each metadata label identifies one or more of:

a type of data depicted in the digital image;

location information; and

relevance of data to one or more subsequent processing operations.

11. A method, comprising:

receiving or capturing a digital image using a mobile device;

using a processor of the mobile device:

determining whether an object depicted in the digital image belongs to a particular object class among a plurality of object classes;

displaying the digital image on a display of the mobile device upon determining the object does not belong to any of the plurality of object classes;

receiving user input via the display of the mobile device, the user input identifying one or more regions of interest in the object;

building a feature vector based at least in part on the user input;

building and/or selecting an extraction model based at least in part on the feature vector;

extracting data from the digital image based at least in part on the extraction model; and

detecting one or more lines of text in the digital image, the detecting comprising

detecting a plurality of connected components non-background elements in the digital image, and

determining a plurality of likely characters based on the plurality of connected components, wherein determining the plurality of likely characters comprises determining whether each of the plurality of connected components is characterized by a predetermined number of light-to-dark transitions in a predetermined direction.

12. The method as recited in claim 11 , wherein the extracting further comprises performing optical character recognition (OCR), wherein the OCR is performed on a selected portion of the digital image excluding one or more portions of the received or captured image.

13. The method as recited in claim 11 , wherein the extracting excludes performing optical character recognition (OCR), and the method further comprising performing optical character recognition on the extracted data.

14. The method as recited in claim 11 , further comprising

generating a new object class based at least in part on the user input, and

wherein the extraction model is configured to extract data from a plurality of objects belonging to the new object class.

15. The method as recited in claim 11 , further comprising validating the extracted data.

16. The method as recited in claim 11 , wherein building the extraction model comprises:

mapping one or more of a feature vector, a list of feature vectors and a feature matrix to one or more object features; and

associating at least one metadata label with each mapped object feature, wherein the metadata label(s) are associated with the digital image.

17. The method as recited in claim 11 , further comprising: training the extraction model based on one or more additional object features of at least one additional object belonging to the object class, and wherein the at least one additional object comprises at least four additional objects.

18. The method as recited in claim 11 , further comprising: performing OCR on one or more regions of the digital image corresponding to one or more of the object features and/or other object features.

19. The method as recited in claim 11 , further comprising:

detecting one or more lines of text in the object, the detecting comprising:

projecting the digital image onto a single dimension;

determining a distribution of light and dark areas along the projection;

determining a plurality of dark pixel densities, each dark pixel density corresponding to a position along the projection;

determining whether each dark pixel density is greater than a probable text line threshold; and

designating each position as a text line upon determining the corresponding dark pixel density is greater than the probable text line threshold.

20. The method as recited in claim 11 , wherein building the extraction model further comprises training the extraction model using one or more of support-vector-machine (SVM) techniques, transductive classification techniques, and maximum entropy discrimination (MED) techniques.

21. The method as recited in claim 11 , further comprising:

projecting the digital image onto a single dimension; and

projecting each color channel of the digital image onto a single channel along the single dimension.

22. A computer program product comprising: non-transitory computer readable storage medium having program code embodied therewith, the program code readable/executable by a mobile device comprising a processor to:

receive or capture a digital image using the mobile device;

use the processor to:

determine whether an object depicted in the digital image belongs to a particular object class among a plurality of object classes based on feature-space discrimination, wherein the feature space discrimination utilizes one or more of support-vector-machine (SVM) techniques, transductive classification techniques, and maximum entropy discrimination (MED) techniques;

determine one or more object features of the object based at least in part on the particular object class and at least partially in response to determining the object belongs to the particular object class;

build or select an extraction model based at least in part on the one or more determined object features; and

extract data from the digital image using the extraction model, the extracting comprising detecting one or more lines of text in the object, and the detecting comprising:

projecting the digital image onto a single dimension;

projecting each color channel of the digital image onto a single channel along the single dimension

determining a distribution of light and dark areas along the projection;

determining a plurality of dark pixel densities, each dark pixel density corresponding to a position along the projection;

determining whether each dark pixel density is greater than a probable text line threshold; and

designating each position as a text line upon determining the corresponding dark pixel density is greater than the probable text line threshold.