Patent ID: 8406568
Filing Date: 2013-03-26
Classification: G06K

Abstract:
1. A method, comprising: generating a set of intensity values for an image by generating by low-pass filtering a previous level of the multi-resolution pyramid with a separable cubic b-spline filter and subsampling a factor of two in each of two directions, the image comprising text at an arbitrary angle of rotation with respect to a horizontal; filtering the intensity values for the image with a bank of separable derivative filters to obtain a set of two-dimensional partial derivatives of the intensity values of the image; generating a set of directional derivatives of the image by using a plurality of oriented filters that are tuned to two or more different orientations; demodulating the set of directional derivatives of the image to obtain energy samples of the image; interpolating the energy samples; determining an orientation of the text of the image based at least in part on a maximum energy value of the interpolated energy samples; and rotating the image based on the determined orientation of the text of the image to align the text with the horizontal.