Patent GB-1294710-A (GB)
Title: Character recognition apparatus
Inventor: DEMER FREDERICK MURRAY
IPC: G06V30/10
Filed: 1970-11-06
Abstract: 1294710 Character recognition INTERNATIONAL BUSINESS MACHINES CORP 6 Nov 1970 [24 Nov 1969] 52873/70 Heading G4R In character recognition apparatus, a representation of a scanned character is reconstituted in a store, and subjected to logical operations to reduce the overall size of the character representation, the reduced version being stored prior to identification. Digitized video from a raster scan of the character is gated into a 9 x 10 storage matrix to reconstitute the character, the bits from each (downwards) scan line of the raster being gated into a respective column of the matrix in such a way that the reconstituted character touches the top of the matrix. Prior and current counters are provided to measure the distance of the uppermost black from the scan line (or matrix column) top in successive scan lines, the counter contents being compared to indicate whether the top edge of the character is rising, level or falling. When rising, the bits already stored in the matrix are shifted down the required number of bit positions to make room at the top of the matrix for the currentlyscanned column which is then rescanned and entered. Shift down by one bit position is achieved by incrementing an auxiliary counter to a count of 14 to produce a "shift down" pulse and terminate incrementing of the prior counter occurring concurrently, the prior counter thus being effectively decremented by one to reflect the new position in the matrix (since the prior counter is a 4-stage binary counter, like the current counter). On the other hand, when falling, the first black bit of the scanned column will be entered into the matrix below the top of the respective matrix column, the row addressing means of the matrix being advanced appropriately. A first transformation is then performed on the 9 x 10 matrix contents to obtain a reduced 5 x 6 version of the character, replacing each bit in a central 5 x 6 area of the 9 x 10 array by the OR of some bits further out than itself (and, in the case of the 2 x 2 bits in the middle, itself as well), the process starting from the centre and working outward, successive rings of bits being reset and then set to their new values (except that the 2 x 2 bits in the middle are not reset first). A second transformation is then performed to delete any all-black columns forming the lateral boundaries of the reduced character, remove redundant columns (viz. one of two identical adjacent columns), and consolidate certain pairs of character columns (depending on number of columns remaining after the other operations of the second transformation and which if any columns are all black), to give finally 3 columns which are transferred to a standard position in the matrix. The operations of the second transformation utilize shifting in each column selectively in a loop or to another column or with loss of shifted out data. Recognition logic responds to the final 3-column character. The second transformation may be omitted, in which case recognition is with respect to the presence of lakes (upper and lower) and bays (top, bottom, left and right) detected by logic responsive to the matrix which is shifted for this feature detection. The first transformation may be preceded by size normalization in which the character is stretched laterally in the matrix so as to fill it, by insertion of white columns and duplication of some columns, depending on the initial width of the character, this being done by ring-shifting some columns, and shifting others serially into further columns, a column being duplicated by doing both to it.