Document image capturing and processing

A method for locating and adjusting a document image consisting of a plurality of pixels within a viewfinder of an image capturing device within a mobile communication device, comprising:

• acquiring an image of a document on the device;
• adjusting the luminosity value of a plurality of the pixels of the quadrilateral document image, wherein the adjustment of the luminosity value of the pixels is carried out in a plurality of subregions of the quadrilateral document image, and the adjustment of luminosity value of each of the pixels comprises blurring the luminosity value of the pixel based upon its luminosity value and the luminosity value of other pixels within a specified distance from the pixel;
• determining the location of the corners of the quadrilateral document image based upon statistical analysis of variations of the adjusted luminosity values, wherein determining the location of each corner comprises:
• a. iteratively quantifying a luminosity difference for each of a plurality of candidate first coordinate pixel locations for the corner in the direction of a first coordinate axis in the two-dimensional plane of the image wherein:
• i. the said luminosity difference is quantified by the difference in adjusted luminosity value of pixels in the vicinity of each said candidate first coordinate pixel locations;
• ii. each luminosity difference is compared to a predetermined value;
• iii. a first set of candidate first coordinate pixel locations is created comprising those candidate first coordinate pixel locations with a luminosity difference greater than said predetermined value;
• b. for each said candidate first coordinate location in said first set, calculating a qualifying number that is equal to the number of other candidate first coordinate pixel locations within said first set with a coordinate value within a specified distance from said candidate first coordinate location;
• c. creating a second set of candidate first coordinate pixel locations comprising those candidate first coordinate pixel locations with the greatest qualifying number;
• d. selecting from said set, as the first coordinate for the corner location, the candidate first coordinate pixel location with the greatest luminosity difference;
• e. performing steps c-f for candidate second coordinate pixel locations for the comer in the direction of a second coordinate axis in the two-dimensional plane of the image to determine the second coordinate for the corner location;
• and
• utilizing said location of said corners to transform the quadrilateral document image into a rectangular document image.