3. The system of claim 1 wherein: the subsets module determines the initial subset of rows for each column having more than one character block aligned in that column in the text rows of the at least one document image, each initial subset of rows comprising one or more of the text rows of the at least one document image having at least one alignment of at least one character block in a selected column, each initial subset of rows having a set of columns comprising the selected column and other columns in the one or more text rows of a corresponding initial subset of rows in which the selected column is present; in the optimum set module, each optimum set comprises a most representative set of columns selected from the set of columns of the corresponding initial subset of rows; and in the division module: each final subset of rows comprises at least one of the one or more text rows of the corresponding initial subset of rows having a corresponding physical structure that is most similar to the most representative set of columns of the corresponding optimum set when compared to physical structures of all of the one or more text rows of the corresponding initial subset of rows; each confidence factor measures a similarity of corresponding physical structures of the at least one of the one or more text rows in one corresponding final subset of rows to each other; and each particular text row has at least one confidence factor corresponding to at least one final subset of rows in which the particular text row is an element.
3. The system of claim 1 wherein: the subsets module determines the initial subset of rows for each column having more than one character block aligned in that column in the text rows of the at least one document image, each initial subset of rows comprising one or more of the text rows of the at least one document image having at least one alignment of at least one character block in a selected column, each initial subset of rows having a set of columns comprising the selected column and other columns in the one or more text rows of a corresponding initial subset of rows in which the selected column is present; in the optimum set module, each optimum set comprises a most representative set of columns selected from the set of columns of the corresponding initial subset of rows; and in the division module: each final subset of rows comprises at least one of the one or more text rows of the corresponding initial subset of rows having a corresponding physical structure that is most similar to the most representative set of columns of the corresponding optimum set when compared to physical structures of all of the one or more text rows of the corresponding initial subset of rows; each confidence factor measures a similarity of corresponding physical structures of the at least one of the one or more text rows in one corresponding final subset of rows to each other; and each particular text row has at least one confidence factor corresponding to at least one final subset of rows in which the particular text row is an element. 4. The system of claim 3 wherein the optimum set module determines the optimum set for each initial subset of rows by: generating a histogram of column frequencies of the set of columns in the corresponding initial subset of rows, each column frequency comprising a number of times a particular column occurs in the corresponding initial subset of rows; determining a threshold of the column frequencies for the corresponding initial subset of rows; and selecting particular columns having the column frequency above the threshold to be included in the most representative set of columns for the corresponding optimum set.