Patent ID: 6771396
Filing Date: 2004-08-03
Classification: H04N

Abstract:
A method of calibrating an image capture system and subsequently capturing an image of a document with the image capture system, wherein calibrating the system comprises:providing an electronic camera for imaging a portion of a document, an actuator for moving the camera over a document support surface and for cooperating with the camera to capture a plurality of overlapping image tiles of the document at different locations over the support surface and with a predetermined degree of overlap, and electronic processing means for joining the plurality of image tiles into a composite image of the document by generating from tile data points associated with each tile a corrected array of tile data points that correct for the expected distortion and predetermined overlap of neighboring image tiles in accordance with transform data for each image tile related to the predetermined overlap and to expected distortion for each image tile; providing a two-dimensional registration array within the field of view of the camera across an area corresponding with the document to be imaged, the registration array having a plurality of individually identifiable location identification features with a predetermined orientation and spacing amongst the features; using the camera to capture a plurality of overlapping image tiles of the registration array at predetermined locations and predetermined overlap, the locations and overlap corresponding to those to be used with the document to be imaged, each image tile having an array of tile data points that cover a plurality of location features; identifying for each image tile a plurality of individual location identification features, associating with the features particular tile data points and from the predetermined orientation and spacing of the specific features determining from the tile data points if there is any image distortion in that image tile; and generating the transform data for each image tile from the identity of the location identification features and the determined distortion; and wherein capturing the image subsequently comprises placing a document on the document support surface; positioning the camera above the document support surface; capturing a plurality of image tiles of the document at a plurality of different predetermined locations over the support surface with a predetermined degree of overlap between neighboring image tiles, each image tile having an array of tile data points and each predetermined location having a predetermined camera field of view; and causing the electronic processing means to generate from the transform data and the tile data points associated with each tile a corrected array of tile data points that correct for the expected distortion and predetermined overlap of neighboring image tiles, and to join the plurality of image tiles into a composite image of the document.