Document scanning system for enhancing information

Claim 2

A document scanning system including scanning means (16) adapted to scan a document containing character information along successive scan lines to provide digital signals representing a matrix of elemental areas, storage means (40-43) adapted to store said digital signals for a selected number of scan lines, and combining means (204-208) adapted to combine selected stored signals from said storage means (40-43) with selected weighting factors, thereby providing enhanced character information, characterized by first delay means (55-63) adapted to provide a scan line delay between sequential scan lines corresponding to a first direction in said matrix, and in that said combining means includes second delay means (216, 220, etc.) adapted to provide an element delay corresponding to a second direction in said matrix in response to the sequential sensing of an elemental area, said combining means being adapted to utilize outputs from said delay means (216, 220, etc.) for use in providing said enhanced character information.

Claim 3

A document scanning system according to claim 1, characterized in that said digital signals are in the form of binary values, and in that said combining means includes shifting means (e.g. 212, 230) adapted to effect multiplication of said digital signals by a power of two.

Claim 4

A document scanning system according to claim 2, characterized in that said selected stored signals form a window included in said matrix, in that said combining means (204, 208) calculates for each element in the window the product of the associated binary value and a corresponding selected weighting factor and further calculates a sum total of all of said products, said combining means (204-208) being effective to shift said window in response to each subsequently sensed element, and to further calculate a new sum total for the shifted window, said combining means being adapted to calculate partial sums of selected products for use in forming the new sum total.

Claim 5

A document scanning system according to claim 3, characterized in that said combining means includes a plurality of multipliers (e.g. 212, 230) for use in calculating said sum totals, the number of said multipliers (e.g. 212, 230) being less than the number of elements in said window.

Claim 8

A method according to claim 5, characterized by the steps of forming a window in said matrix, calculating products for each element in the matrix with a corresonding selected weighting factor, calculating a sum total of all of said products, shifting the window in response to each subsequently sensed element, calculating a new sum total for the shifted window, and calculating partial sums of selected products for use in the new sum total for the shifted window.

Claim 9

A digital filter for use in the enhancement of character information sensed from documents, including input means (70) adapted to receive digital signals representative of a document image, characterized by a plurality of latches (55, 56, etc.) adapted to latch digital signals therein, the input of one of said latches (55) being connected to said input means (70), a plurality of memory means (40, 41, etc.) connected between selected ones of said latches (55, 56, etc.), addressing means (44, 46) connected to said plurality of memory means (40, 41, etc.), and control signal circuit means (48, 66, 68) connected to said latches and to said memory means, such that in response to first control signals on said control signal means (48, 65, 66, 68), digital signals on said input means (70) and digital signals stored at corresponding addresses in said plurality of memory means (40, 41, etc.) are simultaneously latched in said plurality of latches (55-59) and in response to second control signals on said control signal means the contents of said plurality of latches (55-59) are simultaneously stored at corresponding addresses of said plurality of memory means (40-43), the outputs of said plurality of latches (55-59) being connected to combining means (204, 206, 208) including delay means (216, 220, etc.) and adapted to provide enhanced character information.

Claim 10

A digital filter for use in the enhancement of character information sensed from documents, including input means (70) adapted to receive digital signals representative of a document image, characterized by a plurality of latches (55, 56, etc.) adapted to latch digital signals therein, the input of one of said latches (55) being connected to said input means (70), a plurality of memory means (40, 41, etc.) connected between selected ones of said latches (55, 56, etc.), addressing means (44, 46) connected to said plurality of memory means (40, 41, etc.), and control signal circuit means (48, 66, 68) connected to said latches and to said memory means, such that in response to first control signals on said control signal means (48, 65, 66, 68), digital signals on said input means (70) and digital signals stored at corresponding addresses in said plurality of memory means (40, 41, etc.) are simultaneously latched in said plurality of latches (55-59) and in response to second control signals on said control signal means the contents of said plurality of latches (55-59) are simultaneously stored at corresponding addresses of said plurality of memory means (40-43), the outputs of said plurality of latches (55-59) being connected to combining means (204, 206, 208) including delay means (216, 220, etc.) and adapted to provide enhanced character information.

Claim 11

A digital filter according to claim 7, characterized in that said combining means is effective to determine said enhanced character information in accordance with the equation where R(i,j) are enhanced document image element values, W(k,l) are weighting values, D(i+k,j+l) are original document image element values, and a 1 , a 21 b 1 and b 2 are defined integer values.

Claim 12

A digital filter according to claim 8, characterized in that said weighting values W(k,l) have the values of: