APPARATUS AND METHOD FOR DOCUMENT IMAGE ORIENTATION DETECTION

摘要

An apparatus and method for document image orientation detection. When a ratio of a difference between similarities between a current text line and reference samples in two selected candidate orientations is greater than or equal to a first threshold value, 1 is added to a voting value of a candidate orientation corresponding to the largest similarity in the orientations, and when the ratio of the difference is less than the first threshold value, a product of the ratio of the difference and a parameter related to the first threshold value is added to the voting value of the candidate orientation corresponding to the largest similarity in the orientations. Hence, setting a voting value can efficiently lower influence of noise text lines, low-quality text lines and unsupported text lines on the orientation detection, thereby achieving accurate document image orientation detection.

主权项

1. An apparatus for document image orientation detection, comprising:
a voting unit configured to vote for text lines in a document image line by line, the voting unit comprising: a first calculating unit configured to calculate similarities between a current text line and reference samples in multiple candidate orientations; a selecting unit configured to select two candidate orientations from the multiple candidate orientations where the similarities between the current text line and the reference samples in the two selected candidate orientations are largest and second largest; a second calculating unit configured to calculate a first ratio of a difference between the similarities between the current text line and the reference samples in the two selected candidate orientations; and an adding unit configured to add 1 to a voting value of a candidate orientation corresponding to the largest similarity in the two selected candidate orientations when the first ratio of the difference is greater than or equal to a first threshold value, and add a product of the first ratio of the difference and a parameter related to the first threshold value to the voting value of the candidate orientation corresponding to the largest similarity in the two selected candidate orientations when the first ratio of the difference is less than the first threshold value; and the apparatus further comprising: a determining unit configured to determine a document image orientation as a candidate orientation having a largest voting cumulative value in the multiple candidate orientations when a value difference between the largest voting cumulative value and a second largest voting accumulative value in voting accumulative values of the multiple candidate orientations is greater than or equal to a second threshold value.